meshToMesh, mapFieldsPar: Rationalisation

Cell-to-cell interpolation has been moved to a hierarchy separate from
meshToMesh, called cellsToCells. The meshToMesh class is now a
combination of a cellsToCells object and multiple patchToPatch objects.
This means that when only cell-to-cell interpolation is needed a basic
cellsToCells object can be selected.

Cell-to-cell and vol-field-to-vol-field interpolation now has two well
defined sets of functions, with a clear distinction in how weights that
do not sum to unity are handled. Non-unity weights are either
normalised, or a left-over field is provided with which to complete the
weighted sum.

The left-over approach is now consistently applied in mapFieldsPar,
across both the internal and patch fields, if mapping onto an existing
field in the target case. Warning are now generated for invalid
combinations of settings, such as mapping between inconsistent meshes
without a pre-existing target field.

All mapping functions now take fields as const references and return tmp
fields. This avoids the pattern in which non-const fields are provided
which relate to the source, and at some point in the function transfer
to the target. This pattern is difficult to reason about and does not
provide any actual computational advantage, as the fields invariably get
re-allocated as part of the process anyway.

MeshToMesh no longer stores the cutting patches. The set of cutting
patches is not needed anywhere except at the point of mapping a field,
so it is now supplied to the mapping functions as an argument.

The meshToMesh topology changer no longer supports cutting patch
information. This did not previously work. Cutting patches either get
generated as calculated, or they require a pre-existing field to specify
their boundary condition. Neither of these options is suitable for a
run-time mesh change.

More code has been shared with patchToPatch, reducing duplication.

applications/utilities/preProcessing/mapFieldsPar/mapFieldsPar.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -34,7 +34,7 @@ Description
 #include "fvMeshToFvMesh.H"
 #include "mapGeometricFields.H"
 #include "mapClouds.H"
-#include "cellVolumeWeightMethod.H"
+#include "intersectionCellsToCells.H"
 
 using namespace Foam;
 
@@ -56,12 +56,7 @@ void mapConsistentMesh
 
     Info<< nl << "Mapping geometric fields" << endl;
 
-    mapGeometricFields
+    mapGeometricFields(interp, wordReList(), selectedFields, noLagrangian);
-    (
-        interp,
-        selectedFields,
-        noLagrangian
-    );
 
     if (!noLagrangian)
     {
@@ -70,12 +65,12 @@ void mapConsistentMesh
 }
 
 
-void mapSubMesh
+void mapMesh
 (
     const fvMesh& srcMesh,
     const fvMesh& tgtMesh,
     const HashTable<word>& patchMap,
-    const wordList& cuttingPatches,
+    const wordReList& cuttingPatches,
     const word& mapMethod,
     const HashSet<word>& selectedFields,
     const bool noLagrangian
@@ -84,23 +79,11 @@ void mapSubMesh
     Info<< nl << "Creating and mapping fields for time "
         << srcMesh.time().name() << nl << endl;
 
-    fvMeshToFvMesh interp
+    fvMeshToFvMesh interp(srcMesh, tgtMesh, mapMethod, patchMap);
-    (
-        srcMesh,
-        tgtMesh,
-        mapMethod,
-        patchMap,
-        cuttingPatches
-    );
 
     Info<< nl << "Mapping geometric fields" << endl;
 
-    mapGeometricFields
+    mapGeometricFields(interp, cuttingPatches, selectedFields, noLagrangian);
-    (
-        interp,
-        selectedFields,
-        noLagrangian
-    );
 
     if (!noLagrangian)
     {
@@ -194,7 +177,7 @@ int main(int argc, char *argv[])
         args.optionLookupOrDefault<word>
         (
             "mapMethod",
-            cellVolumeWeightMethod::typeName
+            cellsToCellss::intersection::typeName
         )
     );
     Info<< "Mapping method: " << mapMethod << endl;
@@ -210,7 +193,7 @@ int main(int argc, char *argv[])
     #include "createTimes.H"
 
     HashTable<word> patchMap;
-    wordList cuttingPatches;
+    wordReList cuttingPatches;
 
     if (!consistent)
     {
@@ -276,7 +259,7 @@ int main(int argc, char *argv[])
     }
     else
     {
-        mapSubMesh
+        mapMesh
         (
             srcMesh,
             tgtMesh,

applications/utilities/preProcessing/mapFieldsPar/mapGeometricFields.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -35,94 +35,13 @@ License
 namespace Foam
 {
 
-template<class Type>
-void evaluateConstraintTypes(VolField<Type>& fld)
-{
-    typename VolField<Type>::
-        Boundary& fldBf = fld.boundaryFieldRef();
-
-    if
-    (
-        Pstream::defaultCommsType == Pstream::commsTypes::blocking
-     || Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
-    )
-    {
-        label nReq = Pstream::nRequests();
-
-        forAll(fldBf, patchi)
-        {
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                tgtField.initEvaluate(Pstream::defaultCommsType);
-            }
-        }
-
-        // Block for any outstanding requests
-        if
-        (
-            Pstream::parRun()
-         && Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
-        )
-        {
-            Pstream::waitRequests(nReq);
-        }
-
-        forAll(fldBf, patchi)
-        {
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                tgtField.evaluate(Pstream::defaultCommsType);
-            }
-        }
-    }
-    else if (Pstream::defaultCommsType == Pstream::commsTypes::scheduled)
-    {
-        const lduSchedule& patchSchedule =
-            fld.mesh().globalData().patchSchedule();
-
-        forAll(patchSchedule, patchEvali)
-        {
-            label patchi = patchSchedule[patchEvali].patch;
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                if (patchSchedule[patchEvali].init)
-                {
-                    tgtField.initEvaluate(Pstream::commsTypes::scheduled);
-                }
-                else
-                {
-                    tgtField.evaluate(Pstream::commsTypes::scheduled);
-                }
-            }
-        }
-    }
-}
-
-
 template<class Type>
 void mapVolTypeFields
 (
-    const IOobjectList& objects,
+    const fvMeshToFvMesh& interp,
+    const wordReList& cuttingPatches,
     const HashSet<word>& selectedFields,
-    const fvMeshToFvMesh& interp
+    const IOobjectList& objects
 )
 {
     const fvMesh& srcMesh = static_cast<const fvMesh&>(interp.srcMesh());
@@ -134,8 +53,11 @@ void mapVolTypeFields
     {
         const word& fieldName = fieldIter()->name();
 
-        if (selectedFields.empty() || selectedFields.found(fieldName))
+        if (!selectedFields.empty() && !selectedFields.found(fieldName))
         {
+            continue;
+        }
+
         const VolField<Type> fieldSource(*fieldIter(), srcMesh);
 
         typeIOobject<VolField<Type>> targetIO
@@ -143,97 +65,83 @@ void mapVolTypeFields
             fieldName,
             tgtMesh.time().name(),
             tgtMesh,
-                IOobject::MUST_READ
+            IOobject::READ_IF_PRESENT
         );
 
+        // Warnings about inconsistent execution
+        if (targetIO.headerOk() && interp.consistent())
+        {
+            WarningInFunction
+                << "Mapping of field " << fieldName << " will not utilise "
+                << "the corresponding field in the target case, as the map is "
+                << "consistent (i.e., all patches are mapped)" << endl;
+        }
+        if (!targetIO.headerOk() && !interp.consistent())
+        {
+            WarningInFunction
+                << "Cannot map field " << fieldName << " because the "
+                << "map is not consistent (i.e., not all patches are "
+                << "mapped), and there is no corresponding field in "
+                << "the target case" << endl;
+            continue;
+        }
+        if (!targetIO.headerOk() && !cuttingPatches.empty())
+        {
+            WarningInFunction
+                << "Cutting patches will not be used for field " << fieldName
+                << " because no there is no corresponding field in the target "
+                << "case" << endl;
+        }
+
         if (targetIO.headerOk())
         {
-                Info<< "    interpolating onto existing field "
+            Info<< "    mapping into existing field " << fieldName << endl;
-                    << fieldName << endl;
+
             VolField<Type> fieldTarget(targetIO, tgtMesh);
 
-                interp.mapSrcToTgt(fieldSource, fieldTarget);
+            fieldTarget.reset
-
+            (
-                evaluateConstraintTypes(fieldTarget);
+                interp.srcToTgt(fieldSource, fieldTarget, cuttingPatches)
+            );
 
             fieldTarget.write();
         }
         else
         {
-                Info<< "    creating new field "
+            Info<< "    creating new field " << fieldName << endl;
-                    << fieldName << endl;
 
-                targetIO.readOpt() = IOobject::NO_READ;
+            VolField<Type>(targetIO, interp.srcToTgt(fieldSource)).write();
-
-                tmp<VolField<Type>> tfieldTarget
-                (
-                    interp.mapSrcToTgt(fieldSource)
-                );
-
-                VolField<Type> fieldTarget(targetIO, tfieldTarget);
-
-                evaluateConstraintTypes(fieldTarget);
-
-                fieldTarget.write();
-            }
         }
     }
 }
 
-
-template<class Type, template<class> class GeoField>
-void unMappedTypeFields(const IOobjectList& objects)
-{
-    IOobjectList fields = objects.lookupClass(GeoField<Type>::typeName);
-
-    forAllConstIter(IOobjectList, fields, fieldIter)
-    {
-        mvBak(fieldIter()->objectPath(false), "unmapped");
-    }
 }
 
-} // End namespace Foam
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 void Foam::mapGeometricFields
 (
     const fvMeshToFvMesh& interp,
+    const wordReList& cuttingPatches,
     const HashSet<word>& selectedFields,
     const bool noLagrangian
 )
 {
-    const polyMesh& srcMesh = interp.srcMesh();
-    const polyMesh& tgtMesh = interp.tgtMesh();
-
-    {
     // Search for list of source objects for this time
+    const polyMesh& srcMesh = interp.srcMesh();
     IOobjectList objects(srcMesh, srcMesh.time().name());
 
     // Map the fields
     #define MapVolTypeFields(Type, nullArg)                                    \
         mapVolTypeFields<Type>                                                 \
         (                                                                      \
-                objects,                                                       \
+            interp,                                                            \
+            cuttingPatches,                                                    \
             selectedFields,                                                    \
-                interp                                                         \
+            objects                                                            \
         );
     FOR_ALL_FIELD_TYPES(MapVolTypeFields);
     #undef MapVolTypeFields
-    }
-
-    {
-        // Search for list of target objects for this time
-        IOobjectList objects(tgtMesh, tgtMesh.time().name());
-
-        // Mark surface and point fields as unmapped
-        #define UnMappedTypeFields(Type, GeoField)                             \
-            unMappedTypeFields<Type, GeoField>(objects);
-        FOR_ALL_FIELD_TYPES(UnMappedTypeFields, SurfaceField);
-        FOR_ALL_FIELD_TYPES(UnMappedTypeFields, PointField);
-        #undef UnMappedTypeFields
-    }
 }
 
 

applications/utilities/preProcessing/mapFieldsPar/mapGeometricFields.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -47,6 +47,7 @@ class fvMeshToFvMesh;
 void mapGeometricFields
 (
     const fvMeshToFvMesh& interp,
+    const wordReList& cuttingPatches,
     const HashSet<word>& selectedFields,
     const bool noLagrangian
 );

src/finiteVolume/Make/files

@@ -517,5 +517,7 @@ solver/solverNew.C
 
 fvMeshToFvMesh/fvMeshToFvMesh.C
 fvMeshToFvMesh/patchToPatchFvPatchFieldMapper.C
+fvMeshToFvMesh/patchToPatchLeftOverFvPatchFieldMapper.C
+fvMeshToFvMesh/patchToPatchNormalisedFvPatchFieldMapper.C
 
 LIB = $(FOAM_LIBBIN)/libfiniteVolume

src/finiteVolume/fvMeshToFvMesh/fvMeshToFvMesh.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -50,6 +50,15 @@ class fvMeshToFvMesh
 :
     public meshToMesh
 {
+private:
+
+    // Private Member Functions
+
+        //- Evaluate constraint types for the given vol field
+        template<class Type>
+        static void evaluateConstraintTypes(VolField<Type>& fld);
+
+
 public:
 
     //- Run-time type information
@@ -68,47 +77,46 @@ public:
 
     // Member Functions
 
-        // Evaluation
+        // Interpolation
 
-            // Source-to-target volume field mapping
+            //- Interpolate a source vol field to the target with no left
-
+            //  over values specified. If the interpolation weight sum is less
-                //- Interpolate a field with a defined operation. Values
+            //  than one for a face then they will be normalised. If the
-                //  passed in via 'result' are used to initialise the return
+            //  interpolation weight sum is zero for a face then that face's
-                //  value.
+            //  value will be NaN.
             template<class Type>
-                void mapSrcToTgt
+            tmp<VolField<Type>> srcToTgt
             (
-                    const VolField<Type>& field,
+                const VolField<Type>& srcFld
-                    VolField<Type>& result
             ) const;
 
-                //- Interpolate a field with a defined operation. The initial
+            //- Interpolate a source vol field to the target with left over
-                //  values of the result are set to zero.
+            //  values specified. If the interpolation weight sum is less than
+            //  one for a face then the average will include the left over
+            //  value multiplied by one minus the weight sum.
             template<class Type>
-                tmp<VolField<Type>> mapSrcToTgt
+            tmp<VolField<Type>> srcToTgt
             (
-                    const VolField<Type>& field
+                const VolField<Type>& srcFld,
+                const VolField<Type>& leftOverTgtFld,
+                const UList<wordRe>& tgtCuttingPatches
             ) const;
 
-
+            //- Interpolate a source vol internal field to the target with no
-            // Source-to-target volume internal field mapping
+            //  left over values specified. As the corresponding srcToTgt.
-
-                //- Interpolate a field with a defined operation. Values
-                //  passed in via 'result' are used to initialise the return
-                //  value.
             template<class Type>
-                void mapSrcToTgt
+            tmp<VolInternalField<Type>> srcToTgt
             (
-                    const VolInternalField<Type>& field,
+                const VolInternalField<Type>& srcFld
-                    VolInternalField<Type>& result
             ) const;
 
-                //- Interpolate a field with a defined operation. The initial
+            //- Interpolate a source vol internal field to the target with left
-                //  values of the result are set to zero.
+            //  over values specified. As the corresponding srcToTgt.
             template<class Type>
-                tmp<VolInternalField<Type>> mapSrcToTgt
+            tmp<VolInternalField<Type>> srcToTgt
             (
-                    const VolInternalField<Type>& field
+                const VolInternalField<Type>& srcFld,
+                const VolInternalField<Type>& leftOverTgtFld
             ) const;
 };
 

src/finiteVolume/fvMeshToFvMesh/fvMeshToFvMeshTemplates.C

@@ -26,78 +26,105 @@ License
 #include "fvMeshToFvMesh.H"
 #include "directFvPatchFieldMapper.H"
 #include "identityFvPatchFieldMapper.H"
-#include "patchToPatchFvPatchFieldMapper.H"
+#include "patchToPatchNormalisedFvPatchFieldMapper.H"
+#include "patchToPatchLeftOverFvPatchFieldMapper.H"
 
-// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
 template<class Type>
-void Foam::fvMeshToFvMesh::mapSrcToTgt
+void Foam::fvMeshToFvMesh::evaluateConstraintTypes(VolField<Type>& fld)
-(
-    const VolField<Type>& field,
-    VolField<Type>& result
-) const
 {
-    meshToMesh::mapSrcToTgt(field, result.primitiveFieldRef());
+    typename VolField<Type>::Boundary& fldBf = fld.boundaryFieldRef();
 
-    typename VolField<Type>::
+    if
-        Boundary& resultBf = result.boundaryFieldRef();
+    (
-
+        Pstream::defaultCommsType == Pstream::commsTypes::blocking
-    forAll(srcToTgtPatchIDs(), i)
+     || Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
+    )
     {
-        const label srcPatchi = srcToTgtPatchIDs()[i].first();
+        label nReq = Pstream::nRequests();
-        const label tgtPatchi = srcToTgtPatchIDs()[i].second();
 
-        const fvPatchField<Type>& srcField = field.boundaryField()[srcPatchi];
+        forAll(fldBf, patchi)
-        fvPatchField<Type>& tgtField = resultBf[tgtPatchi];
+        {
+            fvPatchField<Type>& tgtField = fldBf[patchi];
 
-        // Clone and map
+            if
-        tmp<fvPatchField<Type>> tnewTgt
             (
-            fvPatchField<Type>::New
+                tgtField.type() == tgtField.patch().patch().type()
-            (
+             && polyPatch::constraintType(tgtField.patch().patch().type())
-                srcField,
-                tgtField.patch(),
-                result(),
-                patchToPatchFvPatchFieldMapper
-                (
-                    srcToTgtPatchToPatches()[i],
-                    true
             )
-            )
+            {
-        );
+                tgtField.initEvaluate(Pstream::defaultCommsType);
-
+            }
-        // Transfer all mapped quantities (value and e.g. gradient) onto
-        // tgtField. Value will get overwritten below.
-        tgtField.map(tnewTgt(), identityFvPatchFieldMapper());
         }
 
-    forAll(tgtCuttingPatchIDs(), i)
+        // Block for any outstanding requests
+        if
+        (
+            Pstream::parRun()
+         && Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
+        )
         {
-        const label patchi = tgtCuttingPatchIDs()[i];
+            Pstream::waitRequests(nReq);
-        fvPatchField<Type>& pf = resultBf[patchi];
+        }
-        pf == pf.patchInternalField();
+
+        forAll(fldBf, patchi)
+        {
+            fvPatchField<Type>& tgtField = fldBf[patchi];
+
+            if
+            (
+                tgtField.type() == tgtField.patch().patch().type()
+             && polyPatch::constraintType(tgtField.patch().patch().type())
+            )
+            {
+                tgtField.evaluate(Pstream::defaultCommsType);
+            }
+        }
+    }
+    else if (Pstream::defaultCommsType == Pstream::commsTypes::scheduled)
+    {
+        const lduSchedule& patchSchedule =
+            fld.mesh().globalData().patchSchedule();
+
+        forAll(patchSchedule, patchEvali)
+        {
+            label patchi = patchSchedule[patchEvali].patch;
+            fvPatchField<Type>& tgtField = fldBf[patchi];
+
+            if
+            (
+                tgtField.type() == tgtField.patch().patch().type()
+             && polyPatch::constraintType(tgtField.patch().patch().type())
+            )
+            {
+                if (patchSchedule[patchEvali].init)
+                {
+                    tgtField.initEvaluate(Pstream::commsTypes::scheduled);
+                }
+                else
+                {
+                    tgtField.evaluate(Pstream::commsTypes::scheduled);
+                }
+            }
+        }
     }
 }
 
 
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
 template<class Type>
-Foam::tmp<Foam::VolField<Type>>
+Foam::tmp<Foam::VolField<Type>> Foam::fvMeshToFvMesh::srcToTgt
-Foam::fvMeshToFvMesh::mapSrcToTgt
 (
-    const VolField<Type>& field
+    const VolField<Type>& srcFld
 ) const
 {
     const fvMesh& tgtMesh = static_cast<const fvMesh&>(meshToMesh::tgtMesh());
 
-    const fvBoundaryMesh& tgtBm = tgtMesh.boundary();
+    // Construct target patch fields as copies of source patch fields, but do
-    const typename VolField<Type>::Boundary& srcBfld =
+    // not map values yet
-        field.boundaryField();
+    PtrList<fvPatchField<Type>> tgtPatchFields(tgtMesh.boundary().size());
-
-    PtrList<fvPatchField<Type>> tgtPatchFields(tgtBm.size());
-
-    // construct tgt boundary patch types as copy of 'field' boundary types
-    // note: this will provide place holders for fields with additional
-    // entries, but these values will need to be reset
     forAll(srcToTgtPatchIDs(), i)
     {
         const label srcPatchi = srcToTgtPatchIDs()[i].first();
@@ -110,7 +137,7 @@ Foam::fvMeshToFvMesh::mapSrcToTgt
                 tgtPatchi,
                 fvPatchField<Type>::New
                 (
-                    srcBfld[srcPatchi],
+                    srcFld.boundaryField()[srcPatchi],
                     tgtMesh.boundary()[tgtPatchi],
                     DimensionedField<Type, volMesh>::null(),
                     directFvPatchFieldMapper
@@ -122,13 +149,14 @@ Foam::fvMeshToFvMesh::mapSrcToTgt
         }
     }
 
-    // Any unset tgtPatchFields become calculated
+    // Create calculated patch fields for any unset target patches. Use
+    // fvPatchField<Type>::New to construct these, rather than using the
+    // calculated constructor directly, so that constraints are maintained.
+    labelList tgtPatchFieldIsUnMapped(tgtPatchFields.size(), false);
     forAll(tgtPatchFields, tgtPatchi)
     {
         if (!tgtPatchFields.set(tgtPatchi))
         {
-            // Note: use factory New method instead of direct generation of
-            //       calculated so we keep constraints
             tgtPatchFields.set
             (
                 tgtPatchi,
@@ -139,75 +167,148 @@ Foam::fvMeshToFvMesh::mapSrcToTgt
                     DimensionedField<Type, volMesh>::null()
                 )
             );
+
+            tgtPatchFieldIsUnMapped[tgtPatchi] =
+                polyPatch::constraintType
+                (
+                    tgtMesh.boundary()[tgtPatchi].patch().type()
+                );
         }
     }
 
-    tmp<VolField<Type>> tresult
+    // Construct the result field
+    tmp<VolField<Type>> ttgtFld =
+        VolField<Type>::New
         (
-        new VolField<Type>
+            typedName("interpolate(" + srcFld.name() + ")"),
-        (
+            srcToTgt<Type>(srcFld.internalField())(),
-            IOobject
-            (
-                typedName("interpolate(" + field.name() + ")"),
-                tgtMesh.time().name(),
-                tgtMesh,
-                IOobject::NO_READ,
-                IOobject::NO_WRITE
-            ),
-            tgtMesh,
-            field.dimensions(),
-            Field<Type>(tgtMesh.nCells(), Zero),
             tgtPatchFields
+        );
+    typename VolField<Type>::Boundary& tgtBfld =
+        ttgtFld.ref().boundaryFieldRef();
+
+    // Mapped patches
+    forAll(srcToTgtPatchIDs(), i)
+    {
+        const label srcPatchi = srcToTgtPatchIDs()[i].first();
+        const label tgtPatchi = srcToTgtPatchIDs()[i].second();
+
+        tgtBfld[tgtPatchi].map
+        (
+            srcFld.boundaryField()[srcPatchi],
+            patchToPatchNormalisedFvPatchFieldMapper
+            (
+                srcToTgtPatchToPatches()[i],
+                true
             )
         );
+    }
 
-    fvMeshToFvMesh::mapSrcToTgt<Type>(field, tresult.ref());
+    // Un-mapped patches. Set values to that of the internal cell field.
+    forAll(tgtBfld, patchi)
+    {
+        if (tgtPatchFieldIsUnMapped[patchi])
+        {
+            fvPatchField<Type>& tgtPfld = tgtBfld[patchi];
+            tgtPfld == tgtPfld.patchInternalField();
+        }
+    }
 
-    return tresult;
+    // Evaluate constraints
+    evaluateConstraintTypes(ttgtFld.ref());
+
+    return ttgtFld;
 }
 
 
 template<class Type>
-void Foam::fvMeshToFvMesh::mapSrcToTgt
+Foam::tmp<Foam::VolField<Type>> Foam::fvMeshToFvMesh::srcToTgt
 (
-    const VolInternalField<Type>& field,
+    const VolField<Type>& srcFld,
-    VolInternalField<Type>& result
+    const VolField<Type>& leftOverTgtFld,
+    const UList<wordRe>& tgtCuttingPatchNames
 ) const
 {
-    meshToMesh::mapSrcToTgt(field, result);
+    // Construct the result field
+    tmp<VolField<Type>> ttgtFld =
+        VolField<Type>::New
+        (
+            typedName("interpolate(" + srcFld.name() + ")"),
+            srcToTgt<Type>(srcFld.v(), leftOverTgtFld.v())(),
+            leftOverTgtFld.boundaryField()
+        );
+    typename VolField<Type>::Boundary& tgtBfld =
+        ttgtFld.ref().boundaryFieldRef();
+
+    // Mapped patches
+    forAll(srcToTgtPatchIDs(), i)
+    {
+        const label srcPatchi = srcToTgtPatchIDs()[i].first();
+        const label tgtPatchi = srcToTgtPatchIDs()[i].second();
+
+        tgtBfld[tgtPatchi].map
+        (
+            leftOverTgtFld.boundaryField()[tgtPatchi],
+            identityFvPatchFieldMapper()
+        );
+        tgtBfld[tgtPatchi].map
+        (
+            srcFld.boundaryField()[srcPatchi],
+            patchToPatchLeftOverFvPatchFieldMapper
+            (
+                srcToTgtPatchToPatches()[i],
+                true
+            )
+        );
+    }
+
+    // Cutting patches. Set values to that of the internal cell field.
+    const labelHashSet tgtCuttingPatchIDs =
+        leftOverTgtFld.mesh().boundaryMesh().patchSet(tgtCuttingPatchNames);
+    forAllConstIter(labelHashSet, tgtCuttingPatchIDs, iter)
+    {
+        tgtBfld[iter.key()] == tgtBfld[iter.key()].patchInternalField();
+    }
+
+    // Evaluate constraints
+    evaluateConstraintTypes(ttgtFld.ref());
+
+    return ttgtFld;
 }
 
 
 template<class Type>
-Foam::tmp<Foam::VolInternalField<Type>>
+Foam::tmp<Foam::VolInternalField<Type>> Foam::fvMeshToFvMesh::srcToTgt
-Foam::fvMeshToFvMesh::mapSrcToTgt
 (
-    const VolInternalField<Type>& field
+    const VolInternalField<Type>& srcFld
 ) const
 {
-    const fvMesh& tgtMesh = static_cast<const fvMesh&>(meshToMesh::tgtMesh());
+    return
-
+        VolInternalField<Type>::New
-    tmp<VolInternalField<Type>> tresult
         (
-        new VolInternalField<Type>
+            typedName("interpolate(" + srcFld.name() + ")"),
-        (
+            static_cast<const fvMesh&>(meshToMesh::tgtMesh()),
-            IOobject
+            srcFld.dimensions(),
-            (
+            srcToTgtCellsToCells().srcToTgt(srcFld)
-                typedName("interpolate(" + field.name() + ")"),
-                tgtMesh.time().name(),
-                tgtMesh,
-                IOobject::NO_READ,
-                IOobject::NO_WRITE
-            ),
-            tgtMesh,
-            field.dimensions(),
-            Field<Type>(tgtMesh.nCells(), Zero)
-        )
         );
+}
 
-    fvMeshToFvMesh::mapSrcToTgt<Type>(field, tresult.ref());
 
-    return tresult;
+template<class Type>
+Foam::tmp<Foam::VolInternalField<Type>> Foam::fvMeshToFvMesh::srcToTgt
+(
+    const VolInternalField<Type>& srcFld,
+    const VolInternalField<Type>& leftOverTgtFld
+) const
+{
+    return
+        VolInternalField<Type>::New
+        (
+            typedName("interpolate(" + srcFld.name() + ")"),
+            static_cast<const fvMesh&>(meshToMesh::tgtMesh()),
+            leftOverTgtFld.dimensions(),
+            srcToTgtCellsToCells().srcToTgt(srcFld, leftOverTgtFld)
+        );
 }
 
 

src/finiteVolume/fvMeshToFvMesh/patchToPatchFvPatchFieldMapper.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -27,13 +27,6 @@ License
 
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
-FOR_ALL_FIELD_TYPES
-(
-    IMPLEMENT_FIELD_MAPPER_OPERATOR,
-    patchToPatchFvPatchFieldMapper
-)
-
-
 void Foam::patchToPatchFvPatchFieldMapper::operator()
 (
     Field<label>& f,

src/finiteVolume/fvMeshToFvMesh/patchToPatchFvPatchFieldMapper.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -50,7 +50,9 @@ class patchToPatchFvPatchFieldMapper
 :
     public fvPatchFieldMapper
 {
-    // Private Data
+protected:
+
+    // Protected Data
 
         //- Patch-to-patch mapping engine
         const patchToPatch& pToP_;
@@ -65,17 +67,6 @@ class patchToPatchFvPatchFieldMapper
         bool hasUnmapped_;
 
 
-    // Private Member Functions
-
-        //- Map from one field to another
-        template<class Type>
-        void map(Field<Type>& f, const Field<Type>& mapF) const;
-
-        //- Map a field and return the result as tmp
-        template<class Type>
-        tmp<Field<Type>> map(const Field<Type>& mapF) const;
-
-
 public:
 
     // Constructors
@@ -124,9 +115,6 @@ public:
 
     // Member Operators
 
-        //- Map a field
-        FOR_ALL_FIELD_TYPES(DEFINE_FIELD_MAPPER_OPERATOR, );
-
         //- Map a label field
         DEFINE_FIELD_MAPPER_OPERATOR(label, );
 

src/finiteVolume/fvMeshToFvMesh/patchToPatchFvPatchFieldMapperTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -27,29 +27,6 @@ License
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-template<class Type>
-void Foam::patchToPatchFvPatchFieldMapper::map
-(
-    Field<Type>& f,
-    const Field<Type>& mapF
-) const
-{
-    f = forward_ ? pToP_.srcToTgt(mapF) : pToP_.tgtToSrc(mapF);
-}
-
-
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::patchToPatchFvPatchFieldMapper::map
-(
-    const Field<Type>& mapF
-) const
-{
-    tmp<Field<Type>> tf(new Field<Type>(size_));
-    map(tf.ref(), mapF);
-    return tf;
-}
-
-
 template<class Type>
 void Foam::patchToPatchFvPatchFieldMapper::operator()
 (
@@ -57,7 +34,7 @@ void Foam::patchToPatchFvPatchFieldMapper::operator()
     const tmp<Field<Type>>& tmapF
 ) const
 {
-    map(f, tmapF());
+    operator()(f, tmapF());
     tmapF.clear();
 }
 
@@ -69,7 +46,7 @@ Foam::patchToPatchFvPatchFieldMapper::operator()
     const tmp<Field<Type>>& tmapF
 ) const
 {
-    tmp<Foam::Field<Type>> tf(map(tmapF()));
+    tmp<Foam::Field<Type>> tf(operator()(tmapF()));
     tmapF.clear();
     return tf;
 }

src/finiteVolume/fvMeshToFvMesh/patchToPatchLeftOverFvPatchFieldMapper.C

@@ -0,0 +1,37 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "patchToPatchLeftOverFvPatchFieldMapper.H"
+
+// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
+
+FOR_ALL_FIELD_TYPES
+(
+    IMPLEMENT_FIELD_MAPPER_OPERATOR,
+    patchToPatchLeftOverFvPatchFieldMapper
+)
+
+
+// ************************************************************************* //

src/finiteVolume/fvMeshToFvMesh/patchToPatchLeftOverFvPatchFieldMapper.H

@@ -0,0 +1,104 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::patchToPatchLeftOverFvPatchFieldMapper
+
+Description
+    FieldMapper which uses a patchToPatch object to map from another patch. The
+    source patch may be differently decomposed and/or geometrically and
+    topologically different from the target.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef patchToPatchLeftOverFvPatchFieldMapper_H
+#define patchToPatchLeftOverFvPatchFieldMapper_H
+
+#include "patchToPatchFvPatchFieldMapper.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+            Class patchToPatchLeftOverFvPatchFieldMapper Declaration
+\*---------------------------------------------------------------------------*/
+
+class patchToPatchLeftOverFvPatchFieldMapper
+:
+    public patchToPatchFvPatchFieldMapper
+{
+    // Private Member Functions
+
+        //- Map from one field to another
+        template<class Type>
+        void map(Field<Type>& f, const Field<Type>& mapF) const;
+
+        //- Map a field and return the result as tmp
+        template<class Type>
+        tmp<Field<Type>> map(const Field<Type>& mapF) const;
+
+
+public:
+
+    // Constructors
+
+        //- Construct given a patch-to-patch and a mapping direction
+        patchToPatchLeftOverFvPatchFieldMapper
+        (
+            const patchToPatch& pToP,
+            const bool forward
+        )
+        :
+            patchToPatchFvPatchFieldMapper(pToP, forward)
+        {}
+
+
+    //- Destructor
+    virtual ~patchToPatchLeftOverFvPatchFieldMapper()
+    {}
+
+
+    // Member Operators
+
+        //- Map a field
+        FOR_ALL_FIELD_TYPES(DEFINE_FIELD_MAPPER_OPERATOR, );
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "patchToPatchLeftOverFvPatchFieldMapperTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/fvMeshToFvMesh/patchToPatchLeftOverFvPatchFieldMapperTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,35 +23,30 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "meshToMeshMethod.H"
+#include "patchToPatchLeftOverFvPatchFieldMapper.H"
 
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-Foam::autoPtr<Foam::meshToMeshMethod> Foam::meshToMeshMethod::New
+template<class Type>
+void Foam::patchToPatchLeftOverFvPatchFieldMapper::map
 (
-    const word& methodName,
+    Field<Type>& f,
-    const polyMesh& src,
+    const Field<Type>& mapF
-    const polyMesh& tgt
+) const
-)
 {
-    if (debug)
+    f = forward_ ? pToP_.srcToTgt(mapF, f) : pToP_.tgtToSrc(mapF, f);
-    {
+}
-        Info<< "Selecting meshToMeshMethod " << methodName << endl;
-    }
 
-    componentsConstructorTable::iterator cstrIter =
-        componentsConstructorTablePtr_->find(methodName);
 
-    if (cstrIter == componentsConstructorTablePtr_->end())
+template<class Type>
-    {
+Foam::tmp<Foam::Field<Type>>
-        FatalErrorInFunction
+Foam::patchToPatchLeftOverFvPatchFieldMapper::map
-            << "Unknown meshToMesh type "
+(
-            << methodName << nl << nl
+    const Field<Type>& mapF
-            << "Valid meshToMesh types are:" << nl
+) const
-            << componentsConstructorTablePtr_->sortedToc() << exit(FatalError);
+{
-    }
+    NotImplemented;
-
+    return tmp<Field<Type>>(nullptr);
-    return autoPtr<meshToMeshMethod>(cstrIter()(src, tgt));
 }
 
 

src/finiteVolume/fvMeshToFvMesh/patchToPatchNormalisedFvPatchFieldMapper.C

@@ -0,0 +1,37 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "patchToPatchNormalisedFvPatchFieldMapper.H"
+
+// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
+
+FOR_ALL_FIELD_TYPES
+(
+    IMPLEMENT_FIELD_MAPPER_OPERATOR,
+    patchToPatchNormalisedFvPatchFieldMapper
+)
+
+
+// ************************************************************************* //

src/finiteVolume/fvMeshToFvMesh/patchToPatchNormalisedFvPatchFieldMapper.H

@@ -0,0 +1,104 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::patchToPatchNormalisedFvPatchFieldMapper
+
+Description
+    FieldMapper which uses a patchToPatch object to map from another patch. The
+    source patch may be differently decomposed and/or geometrically and
+    topologically different from the target.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef patchToPatchNormalisedFvPatchFieldMapper_H
+#define patchToPatchNormalisedFvPatchFieldMapper_H
+
+#include "patchToPatchFvPatchFieldMapper.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+            Class patchToPatchNormalisedFvPatchFieldMapper Declaration
+\*---------------------------------------------------------------------------*/
+
+class patchToPatchNormalisedFvPatchFieldMapper
+:
+    public patchToPatchFvPatchFieldMapper
+{
+    // Private Member Functions
+
+        //- Map from one field to another
+        template<class Type>
+        void map(Field<Type>& f, const Field<Type>& mapF) const;
+
+        //- Map a field and return the result as tmp
+        template<class Type>
+        tmp<Field<Type>> map(const Field<Type>& mapF) const;
+
+
+public:
+
+    // Constructors
+
+        //- Construct given a patch-to-patch and a mapping direction
+        patchToPatchNormalisedFvPatchFieldMapper
+        (
+            const patchToPatch& pToP,
+            const bool forward
+        )
+        :
+            patchToPatchFvPatchFieldMapper(pToP, forward)
+        {}
+
+
+    //- Destructor
+    virtual ~patchToPatchNormalisedFvPatchFieldMapper()
+    {}
+
+
+    // Member Operators
+
+        //- Map a field
+        FOR_ALL_FIELD_TYPES(DEFINE_FIELD_MAPPER_OPERATOR, );
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "patchToPatchNormalisedFvPatchFieldMapperTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/fvMeshToFvMesh/patchToPatchNormalisedFvPatchFieldMapperTemplates.C

@@ -0,0 +1,53 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "patchToPatchNormalisedFvPatchFieldMapper.H"
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+template<class Type>
+void Foam::patchToPatchNormalisedFvPatchFieldMapper::map
+(
+    Field<Type>& f,
+    const Field<Type>& mapF
+) const
+{
+    f = forward_ ? pToP_.srcToTgt(mapF) : pToP_.tgtToSrc(mapF);
+}
+
+
+template<class Type>
+Foam::tmp<Foam::Field<Type>> Foam::patchToPatchNormalisedFvPatchFieldMapper::map
+(
+    const Field<Type>& mapF
+) const
+{
+    tmp<Field<Type>> tf(new Field<Type>(size_));
+    map(tf.ref(), mapF);
+    return tf;
+}
+
+
+// ************************************************************************* //

src/fvMeshTopoChangers/meshToMesh/MeshToMeshMapGeometricFields.H

@@ -46,87 +46,6 @@ Description
 namespace Foam
 {
 
-template<class Type>
-void evaluateConstraintTypes(VolField<Type>& fld)
-{
-    typename VolField<Type>::Boundary& fldBf = fld.boundaryFieldRef();
-
-    if
-    (
-        Pstream::defaultCommsType == Pstream::commsTypes::blocking
-     || Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
-    )
-    {
-        label nReq = Pstream::nRequests();
-
-        forAll(fldBf, patchi)
-        {
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                tgtField.initEvaluate(Pstream::defaultCommsType);
-            }
-        }
-
-        // Block for any outstanding requests
-        if
-        (
-            Pstream::parRun()
-         && Pstream::defaultCommsType == Pstream::commsTypes::nonBlocking
-        )
-        {
-            Pstream::waitRequests(nReq);
-        }
-
-        forAll(fldBf, patchi)
-        {
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                tgtField.evaluate(Pstream::defaultCommsType);
-            }
-        }
-    }
-    else if (Pstream::defaultCommsType == Pstream::commsTypes::scheduled)
-    {
-        const lduSchedule& patchSchedule =
-            fld.mesh().globalData().patchSchedule();
-
-        forAll(patchSchedule, patchEvali)
-        {
-            label patchi = patchSchedule[patchEvali].patch;
-            fvPatchField<Type>& tgtField = fldBf[patchi];
-
-            if
-            (
-                tgtField.type() == tgtField.patch().patch().type()
-             && polyPatch::constraintType(tgtField.patch().patch().type())
-            )
-            {
-                if (patchSchedule[patchEvali].init)
-                {
-                    tgtField.initEvaluate(Pstream::commsTypes::scheduled);
-                }
-                else
-                {
-                    tgtField.evaluate(Pstream::commsTypes::scheduled);
-                }
-            }
-        }
-    }
-}
-
-
 template<class Type>
 void MeshToMeshMapVolFields
 (
@@ -169,8 +88,7 @@ void MeshToMeshMapVolFields
     )
     {
         VolField<Type>& field =
-            const_cast<VolField<Type>&>
+            const_cast<VolField<Type>&>(*fieldIter());
-            (*fieldIter());
 
         if (fvMeshToFvMesh::debug)
         {
@@ -178,8 +96,8 @@ void MeshToMeshMapVolFields
                 << endl;
         }
 
-        field.reset(mapper.mapSrcToTgt(field));
+        field.reset(mapper.srcToTgt(field));
-        evaluateConstraintTypes(field);
+
         field.instance() = field.time().name();
     }
 }
@@ -207,8 +125,7 @@ void MeshToMeshMapVolInternalFields
     )
     {
         VolInternalField<Type>& field =
-            const_cast<VolInternalField<Type>&>
+            const_cast<VolInternalField<Type>&>(*fieldIter());
-            (*fieldIter());
 
         if (fvMeshToFvMesh::debug)
         {
@@ -216,7 +133,8 @@ void MeshToMeshMapVolInternalFields
                 << endl;
         }
 
-        field.reset(mapper.mapSrcToTgt<Type>(field));
+        field.reset(mapper.srcToTgt<Type>(field));
+
         field.instance() = field.time().name();
     }
 }

src/fvMeshTopoChangers/meshToMesh/fvMeshTopoChangersMeshToMesh.C

@@ -30,7 +30,7 @@ License
 #include "pointFields.H"
 #include "meshToMeshAdjustTimeStepFunctionObject.H"
 #include "fvMeshToFvMesh.H"
-#include "cellVolumeWeightMethod.H"
+#include "intersectionCellsToCells.H"
 #include "surfaceToVolVelocity.H"
 #include "MeshToMeshMapGeometricFields.H"
 #include "polyMeshMap.H"
@@ -86,7 +86,6 @@ Foam::fvMeshTopoChangers::meshToMesh::meshToMesh
 :
     fvMeshTopoChanger(mesh),
     dict_(dict),
-    cuttingPatches_(dict.lookupOrDefault("cuttingPatches", wordList::null())),
     times_(dict.lookup("times")),
     timeDelta_(dict.lookup<scalar>("timeDelta")),
     timeIndex_(-1)
@@ -121,8 +120,6 @@ bool Foam::fvMeshTopoChangers::meshToMesh::update()
         );
     }
 
-    bool hasChanged = false;
-
     // Only refine on the first call in a time-step
     if (timeIndex_ != mesh().time().timeIndex())
     {
@@ -130,7 +127,7 @@ bool Foam::fvMeshTopoChangers::meshToMesh::update()
     }
     else
     {
-        return hasChanged;
+        return false;
     }
 
     const scalar userTime = mesh().time().userTimeValue();
@@ -141,8 +138,6 @@ bool Foam::fvMeshTopoChangers::meshToMesh::update()
 
         Info << "Mapping to mesh " << meshDir << endl;
 
-        hasChanged = true;
-
         fvMesh newMesh
         (
             IOobject
@@ -156,52 +151,12 @@ bool Foam::fvMeshTopoChangers::meshToMesh::update()
             fvMesh::stitchType::none
         );
 
-        autoPtr<Foam::fvMeshToFvMesh> mapper;
+        fvMeshToFvMesh mapper
-
-        // Create mesh-to-mesh mapper with support for cuttingPatches
-        // if specified
-        if (cuttingPatches_.size())
-        {
-            HashSet<word> cuttingPatchTable;
-            forAll(cuttingPatches_, i)
-            {
-                cuttingPatchTable.insert(cuttingPatches_[i]);
-            }
-
-            HashTable<word> patchMap(mesh().boundary().size());
-
-            const polyBoundaryMesh& pbm = mesh().boundaryMesh();
-
-            forAll(pbm, i)
-            {
-                if
-                (
-                    !cuttingPatchTable.found(pbm[i].name())
-                 && !isA<processorPolyPatch>(pbm[i])
-                )
-                {
-                    patchMap.insert(pbm[i].name(), pbm[i].name());
-                }
-            }
-
-            mapper = new Foam::fvMeshToFvMesh
         (
             mesh(),
             newMesh,
-                cellVolumeWeightMethod::typeName,
+            cellsToCellss::intersection::typeName
-                patchMap,
-                cuttingPatches_
         );
-        }
-        else
-        {
-            mapper = new Foam::fvMeshToFvMesh
-            (
-                mesh(),
-                newMesh,
-                cellVolumeWeightMethod::typeName
-            );
-        }
 
         mesh().reset(newMesh);
 
@@ -234,11 +189,16 @@ bool Foam::fvMeshTopoChangers::meshToMesh::update()
         // Interpolate U's to Uf's
         interpolateUfs();
 
-        polyMeshMap map(mesh(), mapper());
+        polyMeshMap map(mesh(), mapper);
-        mesh().mapMesh(map);
-    }
 
-    return hasChanged;
+        mesh().mapMesh(map);
+
+        return true;
+    }
+    else
+    {
+        return false;
+    }
 }
 
 

src/fvMeshTopoChangers/meshToMesh/fvMeshTopoChangersMeshToMesh.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -57,10 +57,6 @@ class meshToMesh
         //- Mesh-to-mesh control dictionary
         dictionary dict_;
 
-        //- Optional names of the patches which "cut" the internal mesh
-        //  and hence cannot be mapped from existing patches
-        wordList cuttingPatches_;
-
         //- List of mesh mapping times
         scalarList times_;
 

src/fvModels/interRegion/interRegionHeatTransfer/interRegionHeatTransfer.H

@@ -48,7 +48,7 @@ Usage
 
         nbrRegion       other;
 
-        interpolationMethod cellVolumeWeight;
+        interpolationMethod intersection;
         master          true;
 
         semiImplicit    no;

src/fvModels/interRegion/interRegionModel/interRegionModel.C

@@ -25,7 +25,7 @@ License
 
 #include "interRegionModel.H"
 #include "fvModels.H"
-#include "directMethod.H"
+#include "matchingCellsToCells.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -55,8 +55,10 @@ void Foam::fv::interRegionModel::readCoeffs()
 }
 
 
-void Foam::fv::interRegionModel::setMapper() const
+const Foam::cellsToCells& Foam::fv::interRegionModel::interpolation() const
 {
+    if (!interpolationPtr_.valid())
+    {
         Info<< incrIndent;
 
         if (master_)
@@ -75,16 +77,8 @@ void Foam::fv::interRegionModel::setMapper() const
 
             if (mesh().bounds().overlaps(nbrMesh().bounds()))
             {
-            meshInterpPtr_.reset
+                interpolationPtr_ = cellsToCells::New(interpolationMethod_);
-            (
+                interpolationPtr_->update(mesh(), nbrMesh());
-                new meshToMesh
-                (
-                    mesh(),
-                    nbrMesh(),
-                    interpolationMethod_,
-                    false // not interpolating patches
-                )
-            );
             }
             else
             {
@@ -96,6 +90,9 @@ void Foam::fv::interRegionModel::setMapper() const
         }
 
         Info<< decrIndent;
+    }
+
+    return interpolationPtr_();
 }
 
 
@@ -140,8 +137,8 @@ Foam::fv::interRegionModel::interRegionModel
     fvModel(name, modelType, mesh, dict),
     master_(false),
     nbrRegionName_(word::null),
-    interpolationMethod_(directMethod::typeName),
+    interpolationMethod_(cellsToCellss::matching::typeName),
-    meshInterpPtr_()
+    interpolationPtr_()
 {
     readCoeffs();
 }
@@ -160,7 +157,7 @@ bool Foam::fv::interRegionModel::read(const dictionary& dict)
     if (fvModel::read(dict))
     {
         readCoeffs();
-        setMapper();
+        interpolationPtr_.clear();
         return true;
     }
     else

src/fvModels/interRegion/interRegionModel/interRegionModel.H

@@ -29,14 +29,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef interRegionModel_H
-#define interRegionModel_H
-
 #include "fvModel.H"
 #include "volFields.H"
-#include "autoPtr.H"
+#include "cellsToCells.H"
-#include "meshToMesh.H"
 
+#ifndef interRegionModel_H
+#define interRegionModel_H
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -65,7 +63,7 @@ class interRegionModel
         word interpolationMethod_;
 
         //- Mesh to mesh interpolation object
-        mutable autoPtr<meshToMesh> meshInterpPtr_;
+        mutable autoPtr<cellsToCells> interpolationPtr_;
 
 
     // Private member functions
@@ -73,9 +71,6 @@ class interRegionModel
         //- Non-virtual read
         void readCoeffs();
 
-        //- Set the mesh to mesh interpolation object
-        void setMapper() const;
-
 
 protected:
 
@@ -120,8 +115,8 @@ public:
             //- Return const access to the neighbour mesh
             inline const fvMesh& nbrMesh() const;
 
-            //- Return const access to the mapToMap pointer
+            //- Return const access to the interpolation engine
-            inline const meshToMesh& meshInterp() const;
+            const cellsToCells& interpolation() const;
 
 
         // Interpolation

src/fvModels/interRegion/interRegionModel/interRegionModelI.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2012-2021 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,6 +23,8 @@ License
 
 \*---------------------------------------------------------------------------*/
 
+#include "interRegionModel.H"
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 inline bool Foam::fv::interRegionModel::master() const
@@ -43,15 +45,4 @@ inline const Foam::fvMesh& Foam::fv::interRegionModel::nbrMesh() const
 }
 
 
-inline const Foam::meshToMesh& Foam::fv::interRegionModel::meshInterp() const
-{
-    if (!meshInterpPtr_.valid())
-    {
-        setMapper();
-    }
-
-    return meshInterpPtr_();
-}
-
-
 // ************************************************************************* //

src/fvModels/interRegion/interRegionModel/interRegionModelTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -36,11 +36,11 @@ Foam::fv::interRegionModel::interpolate
 {
     if (master())
     {
-        return meshInterp().mapTgtToSrc(field);
+        return interpolation().tgtToSrc(field);
     }
     else
     {
-        return nbrModel().meshInterp().mapSrcToTgt(field);
+        return nbrModel().interpolation().srcToTgt(field);
     }
 }
 
@@ -54,11 +54,11 @@ void Foam::fv::interRegionModel::interpolate
 {
     if (master())
     {
-        meshInterp().mapTgtToSrc(field, result);
+        result = interpolation().tgtToSrc(field, result);
     }
     else
     {
-        nbrModel().meshInterp().mapSrcToTgt(field, result);
+        result = nbrModel().interpolation().srcToTgt(field, result);
     }
 }
 

src/meshTools/Make/files

@@ -226,13 +226,13 @@ patchToPatch/inverseDistance/inverseDistancePatchToPatch.C
 patchToPatch/intersection/intersectionPatchToPatch.C
 patchToPatch/rays/raysPatchToPatch.C
 
+cellsToCells/cellsToCells/cellsToCells.C
+cellsToCells/cellsToCells/cellsToCellsParallelOps.C
+cellsToCells/matching/matchingCellsToCells.C
+cellsToCells/nearest/nearestCellsToCells.C
+cellsToCells/intersection/intersectionCellsToCells.C
+
 meshToMesh/meshToMesh.C
-meshToMesh/meshToMeshParallelOps.C
-meshToMesh/calcMethod/meshToMeshMethod/meshToMeshMethod.C
-meshToMesh/calcMethod/meshToMeshMethod/meshToMeshMethodNew.C
-meshToMesh/calcMethod/cellVolumeWeight/cellVolumeWeightMethod.C
-meshToMesh/calcMethod/direct/directMethod.C
-meshToMesh/calcMethod/mapNearest/mapNearestMethod.C
 
 mappedPatches/mappedPatchBase/mappedPatchBase.C
 mappedPatches/mappedPolyPatch/mappedPolyPatch.C

src/meshTools/cellsToCells/cellsToCells/cellsToCells.C

@@ -0,0 +1,368 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "cellsToCells.H"
+#include "globalIndex.H"
+#include "PatchTools.H"
+#include "patchToPatchTools.H"
+#include "emptyPolyPatch.H"
+#include "wedgePolyPatch.H"
+#include "processorPolyPatch.H"
+#include "Time.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+    defineTypeNameAndDebug(cellsToCells, 0);
+    defineRunTimeSelectionTable(cellsToCells, word);
+}
+
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+void Foam::cellsToCells::initialise
+(
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh
+)
+{
+    srcLocalTgtCells_.setSize(srcMesh.nCells());
+    srcWeights_.setSize(srcMesh.nCells());
+    forAll(srcLocalTgtCells_, srcCelli)
+    {
+        srcLocalTgtCells_[srcCelli].clear();
+        srcWeights_[srcCelli].clear();
+    }
+
+    tgtLocalSrcCells_.setSize(tgtMesh.nCells());
+    tgtWeights_.setSize(tgtMesh.nCells());
+    forAll(tgtLocalSrcCells_, tgtCelli)
+    {
+        tgtLocalSrcCells_[tgtCelli].clear();
+        tgtWeights_[tgtCelli].clear();
+    }
+}
+
+
+Foam::labelList Foam::cellsToCells::maskCells
+(
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh
+) const
+{
+    boundBox meshBb
+    (
+        max(srcMesh.bounds().min(), tgtMesh.bounds().min()),
+        min(srcMesh.bounds().max(), tgtMesh.bounds().max())
+    );
+
+    meshBb.inflate(0.01);
+
+    const cellList& srcCells = srcMesh.cells();
+    const faceList& srcFaces = srcMesh.faces();
+    const pointField& srcPts = srcMesh.points();
+
+    DynamicList<label> resultDyn(srcMesh.nCells());
+    forAll(srcCells, srcCelli)
+    {
+        const boundBox cellBb
+        (
+            srcCells[srcCelli].points(srcFaces, srcPts),
+            false
+        );
+
+        if (meshBb.overlaps(cellBb))
+        {
+            resultDyn.append(srcCelli);
+        }
+    }
+
+    labelList result;
+    result.transfer(resultDyn);
+    return result;
+}
+
+
+void Foam::cellsToCells::appendNbrCells
+(
+    const label celli,
+    const polyMesh& mesh,
+    const DynamicList<label>& visitedCells,
+    DynamicList<label>& nbrCells
+) const
+{
+    // Get all cell-cells
+    const labelList& allNbrCells = mesh.cellCells()[celli];
+
+    // Filter out cells already visited
+    forAll(allNbrCells, i)
+    {
+        const label nbrCelli = allNbrCells[i];
+
+        if
+        (
+            findIndex(visitedCells, nbrCelli) == -1
+         && findIndex(nbrCells, nbrCelli) == -1
+        )
+        {
+            nbrCells.append(nbrCelli);
+        }
+    }
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::cellsToCells::cellsToCells()
+:
+    singleProcess_(-1),
+    srcLocalTgtCells_(),
+    tgtLocalSrcCells_(),
+    srcWeights_(),
+    tgtWeights_(),
+    srcMapPtr_(nullptr),
+    tgtMapPtr_(nullptr),
+    localSrcProcCellsPtr_(nullptr),
+    localTgtProcCellsPtr_(nullptr),
+    localTgtMeshPtr_(nullptr)
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::cellsToCells::~cellsToCells()
+{}
+
+
+// * * * * * * * * * * * * * * * * Selector  * * * * * * * * * * * * * * * * //
+
+Foam::autoPtr<Foam::cellsToCells> Foam::cellsToCells::New
+(
+    const word& cellsToCellsType
+)
+{
+    wordConstructorTable::iterator cstrIter =
+        wordConstructorTablePtr_->find(cellsToCellsType);
+
+    if (cstrIter == wordConstructorTablePtr_->end())
+    {
+        FatalErrorInFunction
+            << "Unknown " << typeName << " type "
+            << cellsToCellsType << endl << endl
+            << "Valid " << typeName << " types are : " << endl
+            << wordConstructorTablePtr_->sortedToc()
+            << exit(FatalError);
+    }
+
+    return cstrIter()();
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+Foam::remote Foam::cellsToCells::srcToTgtPoint
+(
+    const polyMesh& tgtMesh,
+    const label srcCelli,
+    const point& p
+) const
+{
+    forAll(srcLocalTgtCells_[srcCelli], i)
+    {
+        const label tgtCelli = srcLocalTgtCells_[srcCelli][i];
+
+        const polyMesh& localTgtMesh =
+            singleProcess_ == -1 ? localTgtMeshPtr_() : tgtMesh;
+
+        if (localTgtMesh.pointInCell(p, tgtCelli))
+        {
+            return
+                singleProcess_ == -1
+              ? localTgtProcCellsPtr_()[tgtCelli]
+              : remote(Pstream::myProcNo(), tgtCelli);
+        }
+    }
+
+    return remote();
+}
+
+
+Foam::scalar Foam::cellsToCells::update
+(
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh
+)
+{
+    cpuTime time;
+
+    // Determine numbers of faces on both sides, report, and quit if either
+    // side is empty
+    const label srcTotalSize = returnReduce(srcMesh.nCells(), sumOp<label>());
+    const label tgtTotalSize = returnReduce(tgtMesh.nCells(), sumOp<label>());
+    if (srcTotalSize == 0 || tgtTotalSize == 0)
+    {
+        return 0;
+    }
+
+    Info<< indent << typeName << ": Calculating couplings between "
+        << srcTotalSize << " source cells and " << tgtTotalSize
+        << " target cells" << incrIndent << endl;
+
+    singleProcess_ =
+        patchToPatchTools::singleProcess
+        (
+            srcMesh.nCells(),
+            tgtMesh.nCells()
+        );
+
+    scalar V = 0;
+
+    if (isSingleProcess())
+    {
+        // Do the intersection
+        V = calculate(srcMesh, tgtMesh);
+
+        // Normalise the weights
+        normalise(srcMesh, srcLocalTgtCells_, srcWeights_);
+        normalise(tgtMesh, tgtLocalSrcCells_, tgtWeights_);
+    }
+    else
+    {
+        // Create the target map of overlapping cells. This map gets remote
+        // parts of the target mesh so that everything needed to compute an
+        // intersection is available locally to the source. Use it to create a
+        // source-local target mesh.
+        tgtMapPtr_ =
+            patchToPatchTools::constructDistributionMap
+            (
+                tgtMeshSendCells(srcMesh, tgtMesh)
+            );
+        localTgtProcCellsPtr_.reset
+        (
+            new List<remote>
+            (
+                distributeMesh
+                (
+                    tgtMapPtr_(),
+                    tgtMesh,
+                    localTgtMeshPtr_
+                )
+            )
+        );
+        const polyMesh& localTgtMesh = localTgtMeshPtr_();
+
+        if (debug > 1)
+        {
+            Pout<< "Writing local target mesh: "
+                << localTgtMesh.name() << endl;
+            localTgtMesh.write();
+        }
+
+        // Do the intersection
+        V = calculate(srcMesh, localTgtMesh);
+
+        // Trim the local target mesh
+        trimLocalTgt();
+
+        if (debug > 1)
+        {
+            Pout<< "Writing trimmed local target mesh: "
+                << localTgtMesh.name() << endl;
+            localTgtMesh.write();
+        }
+
+        // Construct the source map
+        srcMapPtr_ =
+            patchToPatchTools::constructDistributionMap
+            (
+                patchToPatchTools::procSendIndices
+                (
+                    tgtLocalSrcCells_,
+                    localTgtProcCellsPtr_()
+                )
+            );
+        localSrcProcCellsPtr_.reset
+        (
+            new List<remote>
+            (
+                patchToPatchTools::distributeAddressing(srcMapPtr_())
+            )
+        );
+
+        // Collect the addressing on the target
+        patchToPatchTools::rDistributeTgtAddressing
+        (
+            tgtMesh.nCells(),
+            tgtMapPtr_(),
+            localSrcProcCellsPtr_(),
+            tgtLocalSrcCells_
+        );
+
+        // Collect the weights on the target
+        patchToPatchTools::rDistributeListList
+        (
+            tgtMesh.nCells(),
+            tgtMapPtr_(),
+            tgtWeights_
+        );
+
+        // Normalise the weights
+        normalise(srcMesh, srcLocalTgtCells_, srcWeights_);
+        normalise(tgtMesh, tgtLocalSrcCells_, tgtWeights_);
+
+        // Collect volume intersection contributions
+        reduce(V, sumOp<scalar>());
+    }
+
+    label nCouples = 0;
+    forAll(srcLocalTgtCells_, srcCelli)
+    {
+        nCouples += srcLocalTgtCells_[srcCelli].size();
+    }
+    forAll(tgtLocalSrcCells_, tgtCelli)
+    {
+        nCouples += tgtLocalSrcCells_[tgtCelli].size();
+    }
+    reduce(nCouples, sumOp<label>());
+
+    if (nCouples != 0)
+    {
+        Info<< indent << "Overlapping volume = " << V << endl
+            << indent << nCouples << " couplings calculated in "
+            << time.cpuTimeIncrement() << 's' << endl;
+    }
+    else
+    {
+        Info<< indent << "No couplings found" << endl;
+    }
+
+    Info<< decrIndent;
+
+    return V;
+}
+
+
+// ************************************************************************* //

src/meshTools/cellsToCells/cellsToCells/cellsToCells.H

@@ -0,0 +1,301 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::cellsToCells
+
+Description
+    Class to calculate interpolative addressing and weights between the cells
+    of two overlapping meshes
+
+SourceFiles
+    cellsToCells.C
+    cellsToCellsParallelOps.C
+    cellsToCellsTemplates.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef cellsToCells_H
+#define cellsToCells_H
+
+#include "remote.H"
+#include "distributionMap.H"
+#include "polyMesh.H"
+#include "runTimeSelectionTables.H"
+#include "treeBoundBox.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                         Class cellsToCells Declaration
+\*---------------------------------------------------------------------------*/
+
+class cellsToCells
+{
+protected:
+
+    // Protected Data
+
+        //- Index of processor that holds all of both sides, or -1
+        label singleProcess_;
+
+        //- For each source cell, the coupled local target cells
+        labelListList srcLocalTgtCells_;
+
+        //- For each target cell, the coupled local source cells
+        labelListList tgtLocalSrcCells_;
+
+        //- For each source cell, the coupled target weights
+        scalarListList srcWeights_;
+
+        //- For each target cell, the coupled source weights
+        scalarListList tgtWeights_;
+
+        //- Map from source patch cells to target-local source patch cells
+        autoPtr<distributionMap> srcMapPtr_;
+
+        //- Map from target patch cells to source-local target patch cells
+        autoPtr<distributionMap> tgtMapPtr_;
+
+        //- When running in parallel, a map from local source cell index to
+        //  source processor and cell index
+        autoPtr<List<remote>> localSrcProcCellsPtr_;
+
+        //- When running in parallel, a map from local target cell index to
+        //  target processor and cell index
+        autoPtr<List<remote>> localTgtProcCellsPtr_;
+
+        //- The target mesh, distributed locally to the source
+        autoPtr<polyMesh> localTgtMeshPtr_;
+
+
+    // Protected Member Functions
+
+        // Intersection
+
+            //- Initialise the addressing and weights
+            void initialise
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            );
+
+            //- Calculate the addressing and weights
+            virtual scalar calculate
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            ) = 0;
+
+            //- Normalise the weights for a given mesh
+            virtual void normalise
+            (
+                const polyMesh& mesh,
+                labelListList& localOtherCells,
+                scalarListList& weights
+            ) const = 0;
+
+
+        // Helpers
+
+            //- Return src cell IDs for the overlap region
+            labelList maskCells
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            ) const;
+
+            //- Append target cell neighbour cells to cellIDs list
+            void appendNbrCells
+            (
+                const label tgtCelli,
+                const polyMesh& mesh,
+                const DynamicList<label>& visitedTgtCells,
+                DynamicList<label>& nbrTgtCellIDs
+            ) const;
+
+
+        // Parallel operations
+
+            //- Determine which target cells need to be sent to the source.
+            //  This is done before intersection. Bound boxes are used to
+            //  estimate what cells will intersect.
+            labelListList tgtMeshSendCells
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            ) const;
+
+            //- Distribute a mesh given its distribution map
+            static List<remote> distributeMesh
+            (
+                const distributionMap& map,
+                const polyMesh& mesh,
+                autoPtr<polyMesh>& localMeshPtr
+            );
+
+            //- Trim the local target addressing and mesh so that communication
+            //  from the target to the source is optimised
+            void trimLocalTgt();
+
+
+public:
+
+    //- Run-time type information
+    TypeName("cellsToCells");
+
+
+    //- Declare runtime constructor selection table
+    declareRunTimeSelectionTable
+    (
+        autoPtr,
+        cellsToCells,
+        word,
+        (),
+        ()
+    );
+
+
+    // Constructors
+
+        //- Construct null
+        cellsToCells();
+
+        //- Disallow default bitwise copy construction
+        cellsToCells(const cellsToCells&) = delete;
+
+
+    //- Destructor
+    virtual ~cellsToCells();
+
+
+    // Selector
+
+        //- Select from name
+        static autoPtr<cellsToCells> New(const word& cellsToCellsType);
+
+
+    // Member Functions
+
+        // Access
+
+            //- Index of the processor holding all cells of the cellsToCells,
+            //  or -1 if spread across multiple processors
+            inline label singleProcess() const;
+
+            //- Is this intersection on a single process?
+            inline bool isSingleProcess() const;
+
+
+        // Interpolation
+
+            //- Interpolate a source cell field to the target with no left
+            //  over values specified. If the interpolation weight sum is less
+            //  than one for a face then they will be normalised. If the
+            //  interpolation weight sum is zero for a face then that face's
+            //  value will be NaN.
+            template<class Type>
+            tmp<Field<Type>> srcToTgt(const Field<Type>& srcFld) const;
+
+            //- Interpolate a source cell field to the target with left over
+            //  values specified. If the interpolation weight sum is less than
+            //  one for a face then the average will include the left over
+            //  value multiplied by one minus the weight sum.
+            template<class Type>
+            tmp<Field<Type>> srcToTgt
+            (
+                const Field<Type>& srcFld,
+                const Field<Type>& leftOverTgtFld
+            ) const;
+
+            //- Interpolate a target cell field to the source with no left
+            //  over values specified. As the corresponding srcToTgt.
+            template<class Type>
+            tmp<Field<Type>> tgtToSrc(const Field<Type>& tgtFld) const;
+
+            //- Interpolate a target cell field to the source with left
+            //  over values specified. As the corresponding srcToTgt.
+            template<class Type>
+            tmp<Field<Type>> tgtToSrc
+            (
+                const Field<Type>& tgtFld,
+                const Field<Type>& leftOverSrcFld
+            ) const;
+
+
+        // Source-to-target point finding
+
+            //- Find the target processor and cell associated with a point in a
+            //  source cell. Note that this will only work with derivations
+            //  that fill a cell's stencil with everything that overlaps that
+            //  cell. qt present this is just cellsToCellss::intersection, but
+            //  we might add a cheaper bound-box based method like
+            //  patchToPatches::rays in future.
+            remote srcToTgtPoint
+            (
+                const polyMesh& tgtMesh,
+                const label srcCelli,
+                const point& p
+            ) const;
+
+
+        // Manipulation
+
+            //- Update addressing and weights for the given meshes. Returns the
+            //  overlapping volume (if that is relevant to the method).
+            scalar update
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            );
+
+
+    // Member Operators
+
+        //- Disallow default bitwise assignment
+        void operator=(const cellsToCells&) = delete;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "cellsToCellsI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "cellsToCellsTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/meshTools/cellsToCells/cellsToCells/cellsToCellsI.H

@@ -0,0 +1,42 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "cellsToCells.H"
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+inline Foam::label Foam::cellsToCells::singleProcess() const
+{
+    return singleProcess_;
+}
+
+
+inline bool Foam::cellsToCells::isSingleProcess() const
+{
+    return singleProcess_ != -1;
+}
+
+
+// ************************************************************************* //

src/meshTools/cellsToCells/cellsToCells/cellsToCellsParallelOps.C

@@ -23,16 +23,36 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "meshToMesh.H"
+#include "cellsToCells.H"
-#include "OFstream.H"
-#include "Time.H"
-#include "globalIndex.H"
 #include "processorPolyPatch.H"
 #include "SubField.H"
+#include "Time.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+inline void offset(label& lst, const label o)
+{
+    lst += o;
+}
+
+template<class ListType>
+void offset(ListType& lst, const label o)
+{
+    forAll(lst, i)
+    {
+        offset(lst[i], o);
+    }
+}
+
+}
+
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-Foam::labelListList Foam::meshToMesh::tgtMeshSendCells
+Foam::labelListList Foam::cellsToCells::tgtMeshSendCells
 (
     const polyMesh& srcMesh,
     const polyMesh& tgtMesh
@@ -85,7 +105,7 @@ Foam::labelListList Foam::meshToMesh::tgtMeshSendCells
 }
 
 
-Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
+Foam::List<Foam::remote> Foam::cellsToCells::distributeMesh
 (
     const distributionMap& map,
     const polyMesh& mesh,
@@ -414,10 +434,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
             internalFaceOffset[proci]
         );
         slice = SubList<face>(fcs, allNInternalFaces[proci]);
-        forAll(slice, i)
+        offset(slice, pointOffset[proci]);
-        {
-            add(slice[i], pointOffset[proci]);
-        }
 
         SubField<label> ownSlice
         (
@@ -426,7 +443,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
             internalFaceOffset[proci]
         );
         ownSlice = SubField<label>(faceOs, allNInternalFaces[proci]);
-        add(ownSlice, cellOffset[proci]);
+        offset(ownSlice, cellOffset[proci]);
 
         SubField<label> nbrSlice
         (
@@ -435,7 +452,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
             internalFaceOffset[proci]
         );
         nbrSlice = SubField<label>(faceNs, allNInternalFaces[proci]);
-        add(nbrSlice, cellOffset[proci]);
+        offset(nbrSlice, cellOffset[proci]);
 
         internalFaceOffset[proci] += allNInternalFaces[proci];
     }
@@ -499,7 +516,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
                             localFaceNeighbours[localFacei] = newOwn;
                         }
 
-                        add(localFaces[localFacei], pointOffset[proci]);
+                        offset(localFaces[localFacei], pointOffset[proci]);
 
                         // mark with unique value
                         fnd() = -2;
@@ -549,7 +566,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
                     }
 
                     localFaces[localFacei] = fcs[i];
-                    add(localFaces[localFacei], pointOffset[proci]);
+                    offset(localFaces[localFacei], pointOffset[proci]);
 
                     localFaceOwners[localFacei] = newOwn;
                     localFaceNeighbours[localFacei] = -1;
@@ -568,7 +585,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
                     const label localFacei = nIntFaces++;
 
                     localFaces[localFacei] = fcs[i];
-                    add(localFaces[localFacei], pointOffset[proci]);
+                    offset(localFaces[localFacei], pointOffset[proci]);
 
                     localFaceOwners[localFacei] = newOwn;
                     localFaceNeighbours[localFacei] = -1;
@@ -617,7 +634,7 @@ Foam::List<Foam::remote> Foam::meshToMesh::distributeMesh
 }
 
 
-void Foam::meshToMesh::trimLocalTgt()
+void Foam::cellsToCells::trimLocalTgt()
 {
     // Determine which local target cells are actually used
     boolList oldLocalTgtCellIsUsed(localTgtProcCellsPtr_().size(), false);

src/meshTools/cellsToCells/cellsToCells/cellsToCellsTemplates.C

@@ -0,0 +1,99 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "cellsToCells.H"
+#include "patchToPatchTools.H"
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::tmp<Foam::Field<Type>>
+Foam::cellsToCells::srcToTgt(const Field<Type>& srcFld) const
+{
+    return
+        patchToPatchTools::interpolate
+        (
+            tgtLocalSrcCells_,
+            tgtWeights_,
+            srcMapPtr_,
+            srcFld
+        );
+}
+
+
+template<class Type>
+Foam::tmp<Foam::Field<Type>> Foam::cellsToCells::srcToTgt
+(
+    const Field<Type>& srcFld,
+    const Field<Type>& leftOverTgtFld
+) const
+{
+    return
+        patchToPatchTools::interpolate
+        (
+            tgtLocalSrcCells_,
+            tgtWeights_,
+            srcMapPtr_,
+            srcFld,
+            leftOverTgtFld
+        );
+}
+
+
+template<class Type>
+Foam::tmp<Foam::Field<Type>>
+Foam::cellsToCells::tgtToSrc(const Field<Type>& tgtFld) const
+{
+    return
+        patchToPatchTools::interpolate
+        (
+            srcLocalTgtCells_,
+            srcWeights_,
+            tgtMapPtr_,
+            tgtFld
+        );
+}
+
+
+template<class Type>
+Foam::tmp<Foam::Field<Type>> Foam::cellsToCells::tgtToSrc
+(
+    const Field<Type>& tgtFld,
+    const Field<Type>& leftOverSrcFld
+) const
+{
+    return
+        patchToPatchTools::interpolate
+        (
+            srcLocalTgtCells_,
+            srcWeights_,
+            tgtMapPtr_,
+            tgtFld,
+            leftOverSrcFld
+        );
+}
+
+
+// ************************************************************************* //

src/meshTools/cellsToCells/intersection/intersectionCellsToCells.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,8 +23,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "cellVolumeWeightMethod.H"
+#include "intersectionCellsToCells.H"
-#include "intersectionPatchToPatch.H"
 #include "indexedOctree.H"
 #include "treeDataCell.H"
 #include "tetOverlapVolume.H"
@@ -34,70 +33,64 @@ License
 
 namespace Foam
 {
-    defineTypeNameAndDebug(cellVolumeWeightMethod, 0);
+namespace cellsToCellss
-    addToRunTimeSelectionTable
+{
-    (
+    defineTypeNameAndDebug(intersection, 0);
-        meshToMeshMethod,
+    addToRunTimeSelectionTable(cellsToCells, intersection, word);
-        cellVolumeWeightMethod,
+}
-        components
-    );
 }
 
 
-const Foam::scalar Foam::cellVolumeWeightMethod::tolerance_ = 1e-6;
+const Foam::scalar Foam::cellsToCellss::intersection::tolerance_ = 1e-6;
 
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-bool Foam::cellVolumeWeightMethod::intersect
+bool Foam::cellsToCellss::intersection::intersect
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const label srcCelli,
     const label tgtCelli
 ) const
 {
-    scalar threshold = tolerance_*src_.cellVolumes()[srcCelli];
+    return
-
+        tetOverlapVolume().cellCellOverlapMinDecomp
-    tetOverlapVolume overlapEngine;
-
-    treeBoundBox bbTgtCell(tgt_.points(), tgt_.cellPoints()[tgtCelli]);
-
-    return overlapEngine.cellCellOverlapMinDecomp
         (
-        src_,
+            srcMesh,
             srcCelli,
-        tgt_,
+            tgtMesh,
             tgtCelli,
-        bbTgtCell,
+            treeBoundBox(tgtMesh.points(), tgtMesh.cellPoints()[tgtCelli]),
-        threshold
+            tolerance_*srcMesh.cellVolumes()[srcCelli]
         );
 }
 
 
-Foam::scalar Foam::cellVolumeWeightMethod::interVol
+Foam::scalar Foam::cellsToCellss::intersection::interVol
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const label srcCelli,
     const label tgtCelli
 ) const
 {
-    tetOverlapVolume overlapEngine;
+    return
-
+        tetOverlapVolume().cellCellOverlapVolumeMinDecomp
-    treeBoundBox bbTgtCell(tgt_.points(), tgt_.cellPoints()[tgtCelli]);
-
-    scalar vol = overlapEngine.cellCellOverlapVolumeMinDecomp
         (
-        src_,
+            srcMesh,
             srcCelli,
-        tgt_,
+            tgtMesh,
             tgtCelli,
-        bbTgtCell
+            treeBoundBox(tgtMesh.points(), tgtMesh.cellPoints()[tgtCelli])
         );
-
-    return vol;
 }
 
 
-bool Foam::cellVolumeWeightMethod::findInitialSeeds
+bool Foam::cellsToCellss::intersection::findInitialSeeds
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const labelList& srcCellIDs,
     const boolList& mapFlag,
     const label startSeedI,
@@ -105,9 +98,9 @@ bool Foam::cellVolumeWeightMethod::findInitialSeeds
     label& tgtSeedI
 ) const
 {
-    const cellList& srcCells = src_.cells();
+    const cellList& srcCells = srcMesh.cells();
-    const faceList& srcFaces = src_.faces();
+    const faceList& srcFaces = srcMesh.faces();
-    const pointField& srcPts = src_.points();
+    const pointField& srcPts = srcMesh.points();
 
     for (label i = startSeedI; i < srcCellIDs.size(); i++)
     {
@@ -117,7 +110,7 @@ bool Foam::cellVolumeWeightMethod::findInitialSeeds
         {
             const labelList tgtIDs
             (
-                tgt_.cellTree().findBox
+                tgtMesh.cellTree().findBox
                 (
                     treeBoundBox(srcCells[srcI].bb(srcPts, srcFaces))
                 )
@@ -127,7 +120,7 @@ bool Foam::cellVolumeWeightMethod::findInitialSeeds
             {
                 const label tgtI = tgtIDs[j];
 
-                if (intersect(srcI, tgtI))
+                if (intersect(srcMesh, tgtMesh, srcI, tgtI))
                 {
                     srcSeedI = srcI;
                     tgtSeedI = tgtI;
@@ -147,8 +140,10 @@ bool Foam::cellVolumeWeightMethod::findInitialSeeds
 }
 
 
-Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
+Foam::scalar Foam::cellsToCellss::intersection::calculateAddressing
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     labelListList& srcToTgtCellAddr,
     scalarListList& srcToTgtCellWght,
     labelListList& tgtToSrcCellAddr,
@@ -165,11 +160,11 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
     label srcCelli = srcSeedI;
     label tgtCelli = tgtSeedI;
 
-    List<DynamicList<label>> srcToTgtAddr(src_.nCells());
+    List<DynamicList<label>> srcToTgtAddr(srcMesh.nCells());
-    List<DynamicList<scalar>> srcToTgtWght(src_.nCells());
+    List<DynamicList<scalar>> srcToTgtWght(srcMesh.nCells());
 
-    List<DynamicList<label>> tgtToSrcAddr(tgt_.nCells());
+    List<DynamicList<label>> tgtToSrcAddr(tgtMesh.nCells());
-    List<DynamicList<scalar>> tgtToSrcWght(tgt_.nCells());
+    List<DynamicList<scalar>> tgtToSrcWght(tgtMesh.nCells());
 
     // list of tgt cell neighbour cells
     DynamicList<label> nbrTgtCells(10);
@@ -178,10 +173,10 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
     DynamicList<label> visitedTgtCells(10);
 
     // list to keep track of tgt cells used to seed src cells
-    labelList seedCells(src_.nCells(), -1);
+    labelList seedCells(srcMesh.nCells(), -1);
     seedCells[srcCelli] = tgtCelli;
 
-    const scalarField& srcVol = src_.cellVolumes();
+    const scalarField& srcVol = srcMesh.cellVolumes();
 
     do
     {
@@ -190,14 +185,14 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
 
         // append initial target cell and neighbours
         nbrTgtCells.append(tgtCelli);
-        appendNbrCells(tgtCelli, tgt_, visitedTgtCells, nbrTgtCells);
+        appendNbrCells(tgtCelli, tgtMesh, visitedTgtCells, nbrTgtCells);
 
         do
         {
             tgtCelli = nbrTgtCells.remove();
             visitedTgtCells.append(tgtCelli);
 
-            scalar vol = interVol(srcCelli, tgtCelli);
+            scalar vol = interVol(srcMesh, tgtMesh, srcCelli, tgtCelli);
 
             // accumulate addressing and weights for valid intersection
             if (vol/srcVol[srcCelli] > tolerance_)
@@ -209,7 +204,7 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
                 tgtToSrcAddr[tgtCelli].append(srcCelli);
                 tgtToSrcWght[tgtCelli].append(vol);
 
-                appendNbrCells(tgtCelli, tgt_, visitedTgtCells, nbrTgtCells);
+                appendNbrCells(tgtCelli, tgtMesh, visitedTgtCells, nbrTgtCells);
 
                 // accumulate intersection volume
                 V += vol;
@@ -222,6 +217,8 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
         // find new source seed cell
         setNextCells
         (
+            srcMesh,
+            tgtMesh,
             startSeedI,
             srcCelli,
             tgtCelli,
@@ -250,8 +247,10 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculateAddressing
 }
 
 
-void Foam::cellVolumeWeightMethod::setNextCells
+void Foam::cellsToCellss::intersection::setNextCells
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     label& startSeedI,
     label& srcCelli,
     label& tgtCelli,
@@ -261,7 +260,7 @@ void Foam::cellVolumeWeightMethod::setNextCells
     labelList& seedCells
 ) const
 {
-    const labelList& srcNbrCells = src_.cellCells()[srcCelli];
+    const labelList& srcNbrCells = srcMesh.cellCells()[srcCelli];
 
     // set possible seeds for later use by querying all src cell neighbours
     // with all visited target cells
@@ -276,7 +275,7 @@ void Foam::cellVolumeWeightMethod::setNextCells
             {
                 label cellT = visitedCells[j];
 
-                if (intersect(cellS, cellT))
+                if (intersect(srcMesh, tgtMesh, cellS, cellT))
                 {
                     seedCells[cellS] = cellT;
 
@@ -332,6 +331,8 @@ void Foam::cellVolumeWeightMethod::setNextCells
         bool restart =
             findInitialSeeds
             (
+                srcMesh,
+                tgtMesh,
                 srcCellIDs,
                 mapFlag,
                 startSeedI,
@@ -352,68 +353,32 @@ void Foam::cellVolumeWeightMethod::setNextCells
 }
 
 
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
-Foam::cellVolumeWeightMethod::cellVolumeWeightMethod
+Foam::scalar Foam::cellsToCellss::intersection::calculate
 (
-    const polyMesh& src,
+    const polyMesh& srcMesh,
-    const polyMesh& tgt
+    const polyMesh& tgtMesh
-)
-:
-    meshToMeshMethod(src, tgt)
-{}
-
-
-// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
-
-Foam::cellVolumeWeightMethod::~cellVolumeWeightMethod()
-{}
-
-
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
-
-const Foam::word& Foam::cellVolumeWeightMethod::patchToPatchMethod() const
-{
-    return patchToPatches::intersection::typeName;
-}
-
-
-Foam::scalar Foam::cellVolumeWeightMethod::calculate
-(
-    labelListList& srcToTgtAddr,
-    scalarListList& srcToTgtWght,
-    labelListList& tgtToSrcAddr,
-    scalarListList& tgtToSrcWght
 )
 {
-    bool ok = initialise
+    initialise(srcMesh, tgtMesh);
-    (
-        srcToTgtAddr,
-        srcToTgtWght,
-        tgtToSrcAddr,
-        tgtToSrcWght
-    );
 
-    if (!ok)
+    // Determine (potentially) participating source mesh cells
-    {
+    const labelList srcCellIDs(maskCells(srcMesh, tgtMesh));
-        return 0;
-    }
 
-    // (potentially) participating source mesh cells
+    // Initialise list to keep track of whether src cell can be mapped
-    const labelList srcCellIDs(maskCells());
+    boolList mapFlag(srcMesh.nCells(), false);
-
-    // list to keep track of whether src cell can be mapped
-    boolList mapFlag(src_.nCells(), false);
     UIndirectList<bool>(mapFlag, srcCellIDs) = true;
 
-    // find initial point in tgt mesh
+    // Find initial point in tgt mesh
     label srcSeedI = -1;
     label tgtSeedI = -1;
     label startSeedI = 0;
-
     bool startWalk =
         findInitialSeeds
         (
+            srcMesh,
+            tgtMesh,
             srcCellIDs,
             mapFlag,
             startSeedI,
@@ -423,26 +388,21 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculate
 
     if (startWalk)
     {
-        const scalar V =
+        return
             calculateAddressing
             (
-                srcToTgtAddr,
+                srcMesh,
-                srcToTgtWght,
+                tgtMesh,
-                tgtToSrcAddr,
+                srcLocalTgtCells_,
-                tgtToSrcWght,
+                srcWeights_,
+                tgtLocalSrcCells_,
+                tgtWeights_,
                 srcSeedI,
                 tgtSeedI,
                 srcCellIDs,
                 mapFlag,
                 startSeedI
             );
-
-        if (debug > 1)
-        {
-            writeConnectivity(src_, tgt_, srcToTgtAddr);
-        }
-
-        return V;
     }
     else
     {
@@ -451,7 +411,7 @@ Foam::scalar Foam::cellVolumeWeightMethod::calculate
 }
 
 
-void Foam::cellVolumeWeightMethod::normalise
+void Foam::cellsToCellss::intersection::normalise
 (
     const polyMesh& srcMesh,
     labelListList& srcToTgtAddr,
@@ -472,4 +432,18 @@ void Foam::cellVolumeWeightMethod::normalise
 }
 
 
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::intersection::intersection()
+:
+    cellsToCells()
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::intersection::~intersection()
+{}
+
+
 // ************************************************************************* //

src/meshTools/cellsToCells/intersection/intersectionCellsToCells.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -22,39 +22,39 @@ License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
 Class
-    Foam::cellVolumeWeightMethod
+    Foam::cellsToCellss::intersection
 
 Description
-    Cell-volume-weighted mesh-to-mesh interpolation class
+    Intersection-based cells-to-cells interpolation class. Volume conservative.
-
-    Volume conservative.
 
 SourceFiles
-    cellVolumeWeightMethod.C
+    intersectionCellsToCells.C
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef cellVolumeWeightMethod_H
+#ifndef intersectionCellsToCells_H
-#define cellVolumeWeightMethod_H
+#define intersectionCellsToCells_H
 
-#include "meshToMeshMethod.H"
+#include "cellsToCells.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
+namespace cellsToCellss
+{
 
 /*---------------------------------------------------------------------------*\
-                   Class cellVolumeWeightMethod Declaration
+                        Class intersection Declaration
 \*---------------------------------------------------------------------------*/
 
-class cellVolumeWeightMethod
+class intersection
 :
-    public meshToMeshMethod
+    public cellsToCells
 {
 private:
 
-    // Private static data
+    // Private Static Data
 
         //- Tolerance used in volume overlap calculations
         static const scalar tolerance_;
@@ -63,15 +63,29 @@ private:
     // Private Member Functions
 
         //- Return the true if cells intersect
-        bool intersect(const label srcCelli, const label tgtCelli) const;
+        bool intersect
+        (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
+            const label srcCelli,
+            const label tgtCelli
+        ) const;
 
         //- Return the intersection volume between two cells
-        scalar interVol(const label srcCelli, const label tgtCelli) const;
+        scalar interVol
+        (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
+            const label srcCelli,
+            const label tgtCelli
+        ) const;
 
         //- Find indices of overlapping cells in src and tgt meshes - returns
         //  true if found a matching pair
         bool findInitialSeeds
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             const labelList& srcCellIDs,
             const boolList& mapFlag,
             const label startSeedI,
@@ -82,6 +96,8 @@ private:
         //- Calculate the mesh-to-mesh addressing and weights
         scalar calculateAddressing
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             labelListList& srcToTgtCellAddr,
             scalarListList& srcToTgtCellWght,
             labelListList& tgtToSrcCellAddr,
@@ -96,6 +112,8 @@ private:
         //- Set the next cells in the advancing front algorithm
         void setNextCells
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             label& startSeedI,
             label& srcCelli,
             label& tgtCelli,
@@ -106,48 +124,48 @@ private:
         ) const;
 
 
-public:
+protected:
 
-    //- Run-time type information
+    // Protected Member Functions
-    TypeName("cellVolumeWeight");
 
+        // Intersection
 
-    // Constructors
+            //- Calculate the addressing and weights
-
-        //- Construct from source and target meshes
-        cellVolumeWeightMethod(const polyMesh& src, const polyMesh& tgt);
-
-
-    //- Destructor
-    virtual ~cellVolumeWeightMethod();
-
-
-    // Member Functions
-
-        //- Get the corresponding patchToPatch method
-        virtual const word& patchToPatchMethod() const;
-
-        //- Calculate addressing and weights
             virtual scalar calculate
             (
-            labelListList& srcToTgtAddr,
+                const polyMesh& srcMesh,
-            scalarListList& srcToTgtWght,
+                const polyMesh& tgtMesh
-            labelListList& tgtToTgtAddr,
-            scalarListList& tgtToTgtWght
             );
 
             //- Normalise the weights for a given mesh
             virtual void normalise
             (
-            const polyMesh& srcMesh,
+                const polyMesh& mesh,
-            labelListList& srcToTgtAddr,
+                labelListList& localOtherCells,
-            scalarListList& srcToTgtWght
+                scalarListList& weights
             ) const;
+
+
+public:
+
+    //- Run-time type information
+    TypeName("intersection");
+
+
+    // Constructors
+
+        //- Construct null
+        intersection();
+
+
+    //- Destructor
+    virtual ~intersection();
 };
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+} // End namespace cellsToCellss
 } // End namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/meshTools/cellsToCells/matching/matchingCellsToCells.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,8 +23,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "directMethod.H"
+#include "matchingCellsToCells.H"
-#include "matchingPatchToPatch.H"
 #include "indexedOctree.H"
 #include "treeDataCell.H"
 #include "addToRunTimeSelectionTable.H"
@@ -33,30 +32,37 @@ License
 
 namespace Foam
 {
-    defineTypeNameAndDebug(directMethod, 0);
+namespace cellsToCellss
-    addToRunTimeSelectionTable(meshToMeshMethod, directMethod, components);
+{
+    defineTypeNameAndDebug(matching, 0);
+    addToRunTimeSelectionTable(cellsToCells, matching, word);
+}
 }
 
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-bool Foam::directMethod::intersect
+bool Foam::cellsToCellss::matching::intersect
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const label srcCelli,
     const label tgtCelli
 ) const
 {
-    return tgt_.pointInCell
+    return tgtMesh.pointInCell
     (
-        src_.cellCentres()[srcCelli],
+        srcMesh.cellCentres()[srcCelli],
         tgtCelli,
         polyMesh::FACE_PLANES
     );
 }
 
 
-bool Foam::directMethod::findInitialSeeds
+bool Foam::cellsToCellss::matching::findInitialSeeds
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const labelList& srcCellIDs,
     const boolList& mapFlag,
     const label startSeedI,
@@ -64,9 +70,9 @@ bool Foam::directMethod::findInitialSeeds
     label& tgtSeedI
 ) const
 {
-    const cellList& srcCells = src_.cells();
+    const cellList& srcCells = srcMesh.cells();
-    const faceList& srcFaces = src_.faces();
+    const faceList& srcFaces = srcMesh.faces();
-    const pointField& srcPts = src_.points();
+    const pointField& srcPts = srcMesh.points();
 
     for (label i = startSeedI; i < srcCellIDs.size(); i++)
     {
@@ -75,9 +81,9 @@ bool Foam::directMethod::findInitialSeeds
         if (mapFlag[srcI])
         {
             const point srcCtr(srcCells[srcI].centre(srcPts, srcFaces));
-            label tgtI = tgt_.cellTree().findInside(srcCtr);
+            label tgtI = tgtMesh.cellTree().findInside(srcCtr);
 
-            if (tgtI != -1 && intersect(srcI, tgtI))
+            if (tgtI != -1 && intersect(srcMesh, tgtMesh, srcI, tgtI))
             {
                 srcSeedI = srcI;
                 tgtSeedI = tgtI;
@@ -96,8 +102,10 @@ bool Foam::directMethod::findInitialSeeds
 }
 
 
-Foam::scalar Foam::directMethod::calculateAddressing
+Foam::scalar Foam::cellsToCellss::matching::calculateAddressing
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     labelListList& srcToTgtCellAddr,
     scalarListList& srcToTgtCellWght,
     labelListList& tgtToSrcCellAddr,
@@ -112,15 +120,15 @@ Foam::scalar Foam::directMethod::calculateAddressing
     scalar V = 0;
 
     // store a list of src cells already mapped
-    labelList srcTgtSeed(src_.nCells(), -1);
+    labelList srcTgtSeed(srcMesh.nCells(), -1);
 
-    List<DynamicList<label>> srcToTgt(src_.nCells());
+    List<DynamicList<label>> srcToTgt(srcMesh.nCells());
-    List<DynamicList<label>> tgtToSrc(tgt_.nCells());
+    List<DynamicList<label>> tgtToSrc(tgtMesh.nCells());
 
     DynamicList<label> srcSeeds(10);
 
-    const scalarField& srcVc = src_.cellVolumes();
+    const scalarField& srcVc = srcMesh.cellVolumes();
-    const scalarField& tgtVc = tgt_.cellVolumes();
+    const scalarField& tgtVc = tgtMesh.cellVolumes();
 
     label srcCelli = srcSeedI;
     label tgtCelli = tgtSeedI;
@@ -140,6 +148,8 @@ Foam::scalar Foam::directMethod::calculateAddressing
         // find new source seed cell
         appendToDirectSeeds
         (
+            srcMesh,
+            tgtMesh,
             mapFlag,
             srcTgtSeed,
             srcSeeds,
@@ -166,8 +176,10 @@ Foam::scalar Foam::directMethod::calculateAddressing
 }
 
 
-void Foam::directMethod::appendToDirectSeeds
+void Foam::cellsToCellss::matching::appendToDirectSeeds
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     boolList& mapFlag,
     labelList& srcTgtSeed,
     DynamicList<label>& srcSeeds,
@@ -175,8 +187,8 @@ void Foam::directMethod::appendToDirectSeeds
     label& tgtSeedI
 ) const
 {
-    const labelList& srcNbr = src_.cellCells()[srcSeedI];
+    const labelList& srcNbr = srcMesh.cellCells()[srcSeedI];
-    const labelList& tgtNbr = tgt_.cellCells()[tgtSeedI];
+    const labelList& tgtNbr = tgtMesh.cellCells()[tgtSeedI];
 
     forAll(srcNbr, i)
     {
@@ -192,7 +204,7 @@ void Foam::directMethod::appendToDirectSeeds
             {
                 label tgtI = tgtNbr[j];
 
-                if (intersect(srcI, tgtI))
+                if (intersect(srcMesh, tgtMesh, srcI, tgtI))
                 {
                     // new match - append to lists
                     found = true;
@@ -224,67 +236,32 @@ void Foam::directMethod::appendToDirectSeeds
     }
 }
 
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
-Foam::directMethod::directMethod
+Foam::scalar Foam::cellsToCellss::matching::calculate
 (
-    const polyMesh& src,
+    const polyMesh& srcMesh,
-    const polyMesh& tgt
+    const polyMesh& tgtMesh
-)
-:
-    meshToMeshMethod(src, tgt)
-{}
-
-
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-Foam::directMethod::~directMethod()
-{}
-
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
-
-const Foam::word& Foam::directMethod::patchToPatchMethod() const
-{
-    return patchToPatches::matching::typeName;
-}
-
-
-Foam::scalar Foam::directMethod::calculate
-(
-    labelListList& srcToTgtAddr,
-    scalarListList& srcToTgtWght,
-    labelListList& tgtToSrcAddr,
-    scalarListList& tgtToSrcWght
 )
 {
-    bool ok = initialise
+    initialise(srcMesh, tgtMesh);
-    (
-        srcToTgtAddr,
-        srcToTgtWght,
-        tgtToSrcAddr,
-        tgtToSrcWght
-    );
 
-    if (!ok)
+    // Determine (potentially) participating source mesh cells
-    {
+    const labelList srcCellIDs(maskCells(srcMesh, tgtMesh));
-        return 0;
-    }
 
-    // (potentially) participating source mesh cells
+    // Initialise list to keep track of whether src cell can be mapped
-    const labelList srcCellIDs(maskCells());
+    boolList mapFlag(srcMesh.nCells(), false);
-
-    // list to keep track of whether src cell can be mapped
-    boolList mapFlag(src_.nCells(), false);
     UIndirectList<bool>(mapFlag, srcCellIDs) = true;
 
-    // find initial point in tgt mesh
+    // Find initial point in tgt mesh
     label srcSeedI = -1;
     label tgtSeedI = -1;
     label startSeedI = 0;
-
     bool startWalk =
         findInitialSeeds
         (
+            srcMesh,
+            tgtMesh,
             srcCellIDs,
             mapFlag,
             startSeedI,
@@ -294,26 +271,21 @@ Foam::scalar Foam::directMethod::calculate
 
     if (startWalk)
     {
-        const scalar V =
+        return
             calculateAddressing
             (
-                srcToTgtAddr,
+                srcMesh,
-                srcToTgtWght,
+                tgtMesh,
-                tgtToSrcAddr,
+                srcLocalTgtCells_,
-                tgtToSrcWght,
+                srcWeights_,
+                tgtLocalSrcCells_,
+                tgtWeights_,
                 srcSeedI,
                 tgtSeedI,
                 srcCellIDs,
                 mapFlag,
                 startSeedI
             );
-
-        if (debug > 1)
-        {
-            writeConnectivity(src_, tgt_, srcToTgtAddr);
-        }
-
-        return V;
     }
     else
     {
@@ -322,7 +294,7 @@ Foam::scalar Foam::directMethod::calculate
 }
 
 
-void Foam::directMethod::normalise
+void Foam::cellsToCellss::matching::normalise
 (
     const polyMesh& srcMesh,
     labelListList& srcToTgtAddr,
@@ -341,4 +313,18 @@ void Foam::directMethod::normalise
 }
 
 
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::matching::matching()
+:
+    cellsToCells()
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::matching::~matching()
+{}
+
+
 // ************************************************************************* //

src/meshTools/cellsToCells/matching/matchingCellsToCells.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -22,35 +22,35 @@ License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
 Class
-    Foam::directMethod
+    Foam::cellsToCellss::matching
 
 Description
-    Direct (one-to-one cell correspondence) mesh-to-mesh interpolation class
+    Matching, one-to-one, cells-to-cells interpolation class.
-
-    Volume conservative.
 
 SourceFiles
-    directMethod.C
+    matchingCellsToCells.C
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef directMethod_H
+#ifndef matchingCellsToCells_H
-#define directMethod_H
+#define matchingCellsToCells_H
 
-#include "meshToMeshMethod.H"
+#include "cellsToCells.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
+namespace cellsToCellss
+{
 
 /*---------------------------------------------------------------------------*\
-                        Class directMethod Declaration
+                        Class matching Declaration
 \*---------------------------------------------------------------------------*/
 
-class directMethod
+class matching
 :
-    public meshToMeshMethod
+    public cellsToCells
 {
 private:
 
@@ -59,6 +59,8 @@ private:
         //- Return the true if cells intersect
         bool intersect
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             const label srcCelli,
             const label tgtCelli
         ) const;
@@ -67,6 +69,8 @@ private:
         //  true if found a matching pair
         bool findInitialSeeds
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             const labelList& srcCellIDs,
             const boolList& mapFlag,
             const label startSeedI,
@@ -77,6 +81,8 @@ private:
         //- Calculate the mesh-to-mesh addressing and weights
         scalar calculateAddressing
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             labelListList& srcToTgtCellAddr,
             scalarListList& srcToTgtCellWght,
             labelListList& tgtToSrcCellAddr,
@@ -91,6 +97,8 @@ private:
         //- Append to list of src mesh seed indices
         void appendToDirectSeeds
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             boolList& mapFlag,
             labelList& srcTgtSeed,
             DynamicList<label>& srcSeeds,
@@ -99,48 +107,48 @@ private:
         ) const;
 
 
-public:
+protected:
 
-    //- Run-time type information
+    // Protected Member Functions
-    TypeName("direct");
 
+        // Intersection
 
-    // Constructors
+            //- Calculate the addressing and weights
-
-        //- Construct from source and target meshes
-        directMethod(const polyMesh& src, const polyMesh& tgt);
-
-
-    //- Destructor
-    virtual ~directMethod();
-
-
-    // Member Functions
-
-        //- Get the corresponding patchToPatch method
-        virtual const word& patchToPatchMethod() const;
-
-        //- Calculate addressing and weights
             virtual scalar calculate
             (
-            labelListList& srcToTgtAddr,
+                const polyMesh& srcMesh,
-            scalarListList& srcToTgtWght,
+                const polyMesh& tgtMesh
-            labelListList& tgtToTgtAddr,
-            scalarListList& tgtToTgtWght
             );
 
             //- Normalise the weights for a given mesh
             virtual void normalise
             (
-            const polyMesh& srcMesh,
+                const polyMesh& mesh,
-            labelListList& srcToTgtAddr,
+                labelListList& localOtherCells,
-            scalarListList& srcToTgtWght
+                scalarListList& weights
             ) const;
+
+
+public:
+
+    //- Run-time type information
+    TypeName("matching");
+
+
+    // Constructors
+
+        //- Construct null
+        matching();
+
+
+    //- Destructor
+    virtual ~matching();
 };
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+} // End namespace cellsToCellss
 } // End namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/meshTools/cellsToCells/nearest/nearestCellsToCells.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,8 +23,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "mapNearestMethod.H"
+#include "nearestCellsToCells.H"
-#include "nearestPatchToPatch.H"
 #include "pointIndexHit.H"
 #include "indexedOctree.H"
 #include "treeDataCell.H"
@@ -34,15 +33,20 @@ License
 
 namespace Foam
 {
-    defineTypeNameAndDebug(mapNearestMethod, 0);
+namespace cellsToCellss
-    addToRunTimeSelectionTable(meshToMeshMethod, mapNearestMethod, components);
+{
+    defineTypeNameAndDebug(nearest, 0);
+    addToRunTimeSelectionTable(cellsToCells, nearest, word);
+}
 }
 
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-bool Foam::mapNearestMethod::findInitialSeeds
+bool Foam::cellsToCellss::nearest::findInitialSeeds
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const labelList& srcCellIDs,
     const boolList& mapFlag,
     const label startSeedI,
@@ -50,7 +54,7 @@ bool Foam::mapNearestMethod::findInitialSeeds
     label& tgtSeedI
 ) const
 {
-    const vectorField& srcCcs = src_.cellCentres();
+    const vectorField& srcCcs = srcMesh.cellCentres();
 
     for (label i = startSeedI; i < srcCellIDs.size(); i++)
     {
@@ -60,7 +64,7 @@ bool Foam::mapNearestMethod::findInitialSeeds
         {
             const point& srcCc = srcCcs[srcI];
             pointIndexHit hit =
-                tgt_.cellTree().findNearest(srcCc, great);
+                tgtMesh.cellTree().findNearest(srcCc, great);
 
             if (hit.hit())
             {
@@ -91,8 +95,10 @@ bool Foam::mapNearestMethod::findInitialSeeds
 }
 
 
-Foam::scalar Foam::mapNearestMethod::calculateAddressing
+Foam::scalar Foam::cellsToCellss::nearest::calculateAddressing
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     labelListList& srcToTgtCellAddr,
     scalarListList& srcToTgtCellWght,
     labelListList& tgtToSrcCellAddr,
@@ -106,11 +112,11 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
 {
     scalar V = 0;
 
-    List<DynamicList<label>> srcToTgt(src_.nCells());
+    List<DynamicList<label>> srcToTgt(srcMesh.nCells());
-    List<DynamicList<label>> tgtToSrc(tgt_.nCells());
+    List<DynamicList<label>> tgtToSrc(tgtMesh.nCells());
 
-    const scalarField& srcVc = src_.cellVolumes();
+    const scalarField& srcVc = srcMesh.cellVolumes();
-    const scalarField& tgtVc = tgt_.cellVolumes();
+    const scalarField& tgtVc = tgtMesh.cellVolumes();
 
     {
         label srcCelli = srcSeedI;
@@ -119,7 +125,7 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
         do
         {
             // find nearest tgt cell
-            findNearestCell(src_, tgt_, srcCelli, tgtCelli);
+            findNearestCell(srcMesh, tgtMesh, srcCelli, tgtCelli);
 
            // store src/tgt cell pair
             srcToTgt[srcCelli].append(tgtCelli);
@@ -134,6 +140,8 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
             // find new source cell
             setNextNearestCells
             (
+                srcMesh,
+                tgtMesh,
                 startSeedI,
                 srcCelli,
                 tgtCelli,
@@ -146,8 +154,8 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
 
     // for the case of multiple source cells per target cell, select the
     // nearest source cell only and discard the others
-    const vectorField& srcCc = src_.cellCentres();
+    const vectorField& srcCc = srcMesh.cellCentres();
-    const vectorField& tgtCc = tgt_.cellCentres();
+    const vectorField& tgtCc = tgtMesh.cellCentres();
 
     forAll(tgtToSrc, targetCelli)
     {
@@ -182,9 +190,10 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
     {
         if (tgtToSrc[tgtCelli].empty())
         {
-            label srcCelli = findMappedSrcCell(tgtCelli, tgtToSrc);
+            label srcCelli =
+                findMappedSrcCell(srcMesh, tgtMesh, tgtCelli, tgtToSrc);
 
-            findNearestCell(tgt_, src_, tgtCelli, srcCelli);
+            findNearestCell(tgtMesh, srcMesh, tgtCelli, srcCelli);
 
             tgtToSrc[tgtCelli].append(srcCelli);
         }
@@ -207,7 +216,7 @@ Foam::scalar Foam::mapNearestMethod::calculateAddressing
 }
 
 
-void Foam::mapNearestMethod::findNearestCell
+void Foam::cellsToCellss::nearest::findNearestCell
 (
     const polyMesh& mesh1,
     const polyMesh& mesh2,
@@ -244,8 +253,10 @@ void Foam::mapNearestMethod::findNearestCell
 }
 
 
-void Foam::mapNearestMethod::setNextNearestCells
+void Foam::cellsToCellss::nearest::setNextNearestCells
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     label& startSeedI,
     label& srcCelli,
     label& tgtCelli,
@@ -253,7 +264,7 @@ void Foam::mapNearestMethod::setNextNearestCells
     const labelList& srcCellIDs
 ) const
 {
-    const labelList& srcNbr = src_.cellCells()[srcCelli];
+    const labelList& srcNbr = srcMesh.cellCells()[srcCelli];
 
     srcCelli = -1;
     forAll(srcNbr, i)
@@ -276,8 +287,10 @@ void Foam::mapNearestMethod::setNextNearestCells
         }
     }
 
-    (void)findInitialSeeds
+    findInitialSeeds
     (
+        srcMesh,
+        tgtMesh,
         srcCellIDs,
         mapFlag,
         startSeedI,
@@ -287,8 +300,10 @@ void Foam::mapNearestMethod::setNextNearestCells
 }
 
 
-Foam::label Foam::mapNearestMethod::findMappedSrcCell
+Foam::label Foam::cellsToCellss::nearest::findMappedSrcCell
 (
+    const polyMesh& srcMesh,
+    const polyMesh& tgtMesh,
     const label tgtCelli,
     const List<DynamicList<label>>& tgtToSrc
 ) const
@@ -313,7 +328,7 @@ Foam::label Foam::mapNearestMethod::findMappedSrcCell
             }
             else
             {
-                const labelList& nbrCells = tgt_.cellCells()[tgtI];
+                const labelList& nbrCells = tgtMesh.cellCells()[tgtI];
 
                 forAll(nbrCells, i)
                 {
@@ -331,68 +346,32 @@ Foam::label Foam::mapNearestMethod::findMappedSrcCell
 }
 
 
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
-Foam::mapNearestMethod::mapNearestMethod
+Foam::scalar Foam::cellsToCellss::nearest::calculate
 (
-    const polyMesh& src,
+    const polyMesh& srcMesh,
-    const polyMesh& tgt
+    const polyMesh& tgtMesh
-)
-:
-    meshToMeshMethod(src, tgt)
-{}
-
-
-// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
-
-Foam::mapNearestMethod::~mapNearestMethod()
-{}
-
-
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
-
-const Foam::word& Foam::mapNearestMethod::patchToPatchMethod() const
-{
-    return patchToPatches::nearest::typeName;
-}
-
-
-Foam::scalar Foam::mapNearestMethod::calculate
-(
-    labelListList& srcToTgtAddr,
-    scalarListList& srcToTgtWght,
-    labelListList& tgtToSrcAddr,
-    scalarListList& tgtToSrcWght
 )
 {
-    bool ok = initialise
+    initialise(srcMesh, tgtMesh);
-    (
-        srcToTgtAddr,
-        srcToTgtWght,
-        tgtToSrcAddr,
-        tgtToSrcWght
-    );
 
-    if (!ok)
+    // Determine (potentially) participating source mesh cells
-    {
+    const labelList srcCellIDs(maskCells(srcMesh, tgtMesh));
-        return 0;
-    }
 
-    // (potentially) participating source mesh cells
+    // Initialise list to keep track of whether src cell can be mapped
-    const labelList srcCellIDs(maskCells());
+    boolList mapFlag(srcMesh.nCells(), false);
-
-    // list to keep track of whether src cell can be mapped
-    boolList mapFlag(src_.nCells(), false);
     UIndirectList<bool>(mapFlag, srcCellIDs) = true;
 
-    // find initial point in tgt mesh
+    // Find initial point in tgt mesh
     label srcSeedI = -1;
     label tgtSeedI = -1;
     label startSeedI = 0;
-
     bool startWalk =
         findInitialSeeds
         (
+            srcMesh,
+            tgtMesh,
             srcCellIDs,
             mapFlag,
             startSeedI,
@@ -402,26 +381,21 @@ Foam::scalar Foam::mapNearestMethod::calculate
 
     if (startWalk)
     {
-        const scalar V =
+        return
             calculateAddressing
             (
-                srcToTgtAddr,
+                srcMesh,
-                srcToTgtWght,
+                tgtMesh,
-                tgtToSrcAddr,
+                srcLocalTgtCells_,
-                tgtToSrcWght,
+                srcWeights_,
+                tgtLocalSrcCells_,
+                tgtWeights_,
                 srcSeedI,
                 tgtSeedI,
                 srcCellIDs,
                 mapFlag,
                 startSeedI
             );
-
-        if (debug > 1)
-        {
-            writeConnectivity(src_, tgt_, srcToTgtAddr);
-        }
-
-        return V;
     }
     else
     {
@@ -430,7 +404,7 @@ Foam::scalar Foam::mapNearestMethod::calculate
 }
 
 
-void Foam::mapNearestMethod::normalise
+void Foam::cellsToCellss::nearest::normalise
 (
     const polyMesh& srcMesh,
     labelListList& srcToTgtAddr,
@@ -449,4 +423,18 @@ void Foam::mapNearestMethod::normalise
 }
 
 
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::nearest::nearest()
+:
+    cellsToCells()
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
+
+Foam::cellsToCellss::nearest::~nearest()
+{}
+
+
 // ************************************************************************* //

src/meshTools/cellsToCells/nearest/nearestCellsToCells.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2013-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -22,39 +22,35 @@ License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
 Class
-    Foam::mapNearestMethod
+    Foam::cellsToCellss::nearest
 
 Description
-    Map nearest mesh-to-mesh interpolation class
+    Nearest cells-to-cells interpolation class.
-
-    Not volume conservative.
-    - cells outside other meshes bounding box do not get mapped
-      (initial filtering)
-    - all remaining cells will be mapped (with weight 1!)
-    - so take care when mapping meshes with different bounding boxes!
 
 SourceFiles
-    mapNearestMethod.C
+    nearestCellsToCells.C
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef mapNearestMethod_H
+#ifndef nearestCellsToCells_H
-#define mapNearestMethod_H
+#define nearestCellsToCells_H
 
-#include "meshToMeshMethod.H"
+#include "cellsToCells.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
+namespace cellsToCellss
+{
 
 /*---------------------------------------------------------------------------*\
-                      Class mapNearestMethod Declaration
+                           Class nearest Declaration
 \*---------------------------------------------------------------------------*/
 
-class mapNearestMethod
+class nearest
 :
-    public meshToMeshMethod
+    public cellsToCells
 {
 private:
 
@@ -64,6 +60,8 @@ private:
         //  true if found a matching pair
         bool findInitialSeeds
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             const labelList& srcCellIDs,
             const boolList& mapFlag,
             const label startSeedI,
@@ -74,6 +72,8 @@ private:
         //- Calculate the mesh-to-mesh addressing and weights
         scalar calculateAddressing
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             labelListList& srcToTgtCellAddr,
             scalarListList& srcToTgtCellWght,
             labelListList& tgtToSrcCellAddr,
@@ -97,6 +97,8 @@ private:
         //- Set the next cells for the marching front algorithm
         void setNextNearestCells
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             label& startSeedI,
             label& srcCelli,
             label& tgtCelli,
@@ -107,53 +109,55 @@ private:
         //- Find a source cell mapped to target cell tgtCelli
         label findMappedSrcCell
         (
+            const polyMesh& srcMesh,
+            const polyMesh& tgtMesh,
             const label tgtCelli,
             const List<DynamicList<label>>& tgtToSrc
         ) const;
 
 
+protected:
+
+    // Protected Member Functions
+
+        // Intersection
+
+            //- Calculate the addressing and weights
+            virtual scalar calculate
+            (
+                const polyMesh& srcMesh,
+                const polyMesh& tgtMesh
+            );
+
+            //- Normalise the weights for a given mesh
+            virtual void normalise
+            (
+                const polyMesh& mesh,
+                labelListList& localOtherCells,
+                scalarListList& weights
+            ) const;
+
+
 public:
 
     //- Run-time type information
-    TypeName("mapNearest");
+    TypeName("nearest");
 
 
     // Constructors
 
-        //- Construct from source and target meshes
+        //- Construct null
-        mapNearestMethod(const polyMesh& src, const polyMesh& tgt);
+        nearest();
 
 
     //- Destructor
-    virtual ~mapNearestMethod();
+    virtual ~nearest();
-
-
-    // Member Functions
-
-        //- Get the corresponding patchToPatch method
-        virtual const word& patchToPatchMethod() const;
-
-        //- Calculate addressing and weights
-        virtual scalar calculate
-        (
-            labelListList& srcToTgtAddr,
-            scalarListList& srcToTgtWght,
-            labelListList& tgtToTgtAddr,
-            scalarListList& tgtToTgtWght
-        );
-
-        //- Normalise the weights for a given mesh
-        virtual void normalise
-        (
-            const polyMesh& srcMesh,
-            labelListList& srcToTgtAddr,
-            scalarListList& srcToTgtWght
-        ) const;
 };
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+} // End namespace cellsToCellss
 } // End namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/meshTools/meshToMesh/calcMethod/meshToMeshMethod/meshToMeshMethod.C

@@ -1,184 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "HashTable.H"
-#include "meshToMeshMethod.H"
-#include "OFstream.H"
-#include "Time.H"
-#include "treeBoundBox.H"
-
-// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
-
-namespace Foam
-{
-    defineTypeNameAndDebug(meshToMeshMethod, 0);
-    defineRunTimeSelectionTable(meshToMeshMethod, components);
-}
-
-
-// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
-
-Foam::labelList Foam::meshToMeshMethod::maskCells() const
-{
-    boundBox intersectBb
-    (
-        max(src_.bounds().min(), tgt_.bounds().min()),
-        min(src_.bounds().max(), tgt_.bounds().max())
-    );
-
-    intersectBb.inflate(0.01);
-
-    const cellList& srcCells = src_.cells();
-    const faceList& srcFaces = src_.faces();
-    const pointField& srcPts = src_.points();
-
-    DynamicList<label> cells(src_.nCells());
-    forAll(srcCells, srcI)
-    {
-        boundBox cellBb(srcCells[srcI].points(srcFaces, srcPts), false);
-        if (intersectBb.overlaps(cellBb))
-        {
-            cells.append(srcI);
-        }
-    }
-
-    if (debug)
-    {
-        Pout<< "participating source mesh cells: " << cells.size() << endl;
-    }
-
-    return move(cells);
-}
-
-
-void Foam::meshToMeshMethod::appendNbrCells
-(
-    const label celli,
-    const polyMesh& mesh,
-    const DynamicList<label>& visitedCells,
-    DynamicList<label>& nbrCellIDs
-) const
-{
-    const labelList& nbrCells = mesh.cellCells()[celli];
-
-    // filter out cells already visited from cell neighbours
-    forAll(nbrCells, i)
-    {
-        label nbrCelli = nbrCells[i];
-
-        if
-        (
-            (findIndex(visitedCells, nbrCelli) == -1)
-         && (findIndex(nbrCellIDs, nbrCelli) == -1)
-        )
-        {
-            nbrCellIDs.append(nbrCelli);
-        }
-    }
-}
-
-
-bool Foam::meshToMeshMethod::initialise
-(
-    labelListList& srcToTgtAddr,
-    scalarListList& srcToTgtWght,
-    labelListList& tgtToSrcAddr,
-    scalarListList& tgtToSrcWght
-) const
-{
-    srcToTgtAddr.setSize(src_.nCells());
-    srcToTgtWght.setSize(src_.nCells());
-    tgtToSrcAddr.setSize(tgt_.nCells());
-    tgtToSrcWght.setSize(tgt_.nCells());
-
-    return src_.nCells() && tgt_.nCells();
-}
-
-
-void Foam::meshToMeshMethod::writeConnectivity
-(
-    const polyMesh& mesh1,
-    const polyMesh& mesh2,
-    const labelListList& mesh1ToMesh2Addr
-) const
-{
-    Pout<< "Source size = " << mesh1.nCells() << endl;
-    Pout<< "Target size = " << mesh2.nCells() << endl;
-
-    word fName("addressing_" + mesh1.name() + "_to_" + mesh2.name());
-
-    if (Pstream::parRun())
-    {
-        fName = fName +  "_proc" + Foam::name(Pstream::myProcNo());
-    }
-
-    OFstream os(src_.time().path()/fName + ".obj");
-
-    label vertI = 0;
-    forAll(mesh1ToMesh2Addr, i)
-    {
-        const labelList& addr = mesh1ToMesh2Addr[i];
-        forAll(addr, j)
-        {
-            label celli = addr[j];
-            const vector& c0 = mesh1.cellCentres()[i];
-
-            const cell& c = mesh2.cells()[celli];
-            const pointField pts(c.points(mesh2.faces(), mesh2.points()));
-            forAll(pts, j)
-            {
-                const point& p = pts[j];
-                os  << "v " << p.x() << ' ' << p.y() << ' ' << p.z() << nl;
-                vertI++;
-                os  << "v " << c0.x() << ' ' << c0.y() << ' ' << c0.z()
-                    << nl;
-                vertI++;
-                os  << "l " << vertI - 1 << ' ' << vertI << nl;
-            }
-        }
-    }
-}
-
-
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
-
-Foam::meshToMeshMethod::meshToMeshMethod
-(
-    const polyMesh& src,
-    const polyMesh& tgt
-)
-:
-    src_(src),
-    tgt_(tgt)
-{}
-
-
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-Foam::meshToMeshMethod::~meshToMeshMethod()
-{}
-
-
-// ************************************************************************* //

src/meshTools/meshToMesh/calcMethod/meshToMeshMethod/meshToMeshMethod.H

@@ -1,199 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2013-2022 OpenFOAM Foundation
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Class
-    Foam::meshToMeshMethod
-
-Description
-    Base class for mesh-to-mesh calculation methods
-
-SourceFiles
-    meshToMeshMethod.C
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef meshToMeshMethod_H
-#define meshToMeshMethod_H
-
-#include "polyMesh.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-/*---------------------------------------------------------------------------*\
-                      Class meshToMeshMethod Declaration
-\*---------------------------------------------------------------------------*/
-
-class meshToMeshMethod
-{
-    // Private static data
-
-        //- Map from mesh-to-mesh method to patch-to-patch method
-        static HashTable<word> meshToMeshToPatchToPatchMethod_;
-
-
-protected:
-
-    // Protected data
-
-        //- Reference to the source mesh
-        const polyMesh& src_;
-
-        //- Reference to the target mesh
-        const polyMesh& tgt_;
-
-
-    // Protected Member Functions
-
-        //- Return src cell IDs for the overlap region
-        labelList maskCells() const;
-
-        //- Append target cell neighbour cells to cellIDs list
-        void appendNbrCells
-        (
-            const label tgtCelli,
-            const polyMesh& mesh,
-            const DynamicList<label>& visitedTgtCells,
-            DynamicList<label>& nbrTgtCellIDs
-        ) const;
-
-        //- Initialise the arrays used to store the intersection result. Return
-        //  whether or not an intersection is possible.
-        bool initialise
-        (
-            labelListList& srcToTgtAddr,
-            scalarListList& srcToTgtWght,
-            labelListList& tgtToTgtAddr,
-            scalarListList& tgtToTgtWght
-        ) const;
-
-        //- Write the connectivity for debugging
-        void writeConnectivity
-        (
-            const polyMesh& mesh1,
-            const polyMesh& mesh2,
-            const labelListList& mesh1ToMesh2Addr
-        ) const;
-
-
-public:
-
-    //- Run-time type information
-    TypeName("meshToMeshMethod");
-
-
-    //- Declare runtime constructor selection table
-    declareRunTimeSelectionTable
-    (
-        autoPtr,
-        meshToMeshMethod,
-        components,
-        (
-            const polyMesh& src,
-            const polyMesh& tgt
-        ),
-        (src, tgt)
-    );
-
-
-    // Constructors
-
-        //- Construct from source and target meshes
-        meshToMeshMethod(const polyMesh& src, const polyMesh& tgt);
-
-        //- Disallow default bitwise copy construction
-        meshToMeshMethod(const meshToMeshMethod&) = delete;
-
-
-    //- Selector
-    static autoPtr<meshToMeshMethod> New
-    (
-        const word& methodName,
-        const polyMesh& src,
-        const polyMesh& tgt
-    );
-
-
-    //- Destructor
-    virtual ~meshToMeshMethod();
-
-
-    // Member Functions
-
-        //- Get the corresponding patch-to-patch method
-        virtual const word& patchToPatchMethod() const = 0;
-
-
-        // Evaluate
-
-            //- Calculate addressing and weights
-            virtual scalar calculate
-            (
-                labelListList& srcToTgtAddr,
-                scalarListList& srcToTgtWght,
-                labelListList& tgtToTgtAddr,
-                scalarListList& tgtToTgtWght
-            ) = 0;
-
-            //- Normalise the weights for a given mesh
-            virtual void normalise
-            (
-                const polyMesh& srcMesh,
-                labelListList& srcToTgtAddr,
-                scalarListList& srcToTgtWght
-            ) const = 0;
-
-
-        // Access
-
-            //- Return const access to the source mesh
-            inline const polyMesh& src() const
-            {
-                return src_;
-            }
-
-            //- Return const access to the target mesh
-            inline const polyMesh& tgt() const
-            {
-                return tgt_;
-            }
-
-
-    // Member Operators
-
-        //- Disallow default bitwise assignment
-        void operator=(const meshToMeshMethod&) = delete;
-};
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //

src/meshTools/meshToMesh/meshToMesh.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2012-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -24,12 +24,10 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "meshToMesh.H"
-#include "globalIndex.H"
-#include "meshToMeshMethod.H"
 #include "PatchTools.H"
-#include "patchToPatchTools.H"
+#include "emptyPolyPatch.H"
+#include "wedgePolyPatch.H"
 #include "processorPolyPatch.H"
-#include "Time.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -39,200 +37,25 @@ namespace Foam
 }
 
 
-// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-Foam::scalar Foam::meshToMesh::calculateCellToCells(const word& methodName)
+Foam::meshToMesh::meshToMesh
-{
-    Info<< "Creating mesh-to-mesh addressing for " << srcMesh_.name()
-        << " and " << tgtMesh_.name() << " regions using "
-        << methodName << endl;
-
-    singleProcess_ =
-        patchToPatchTools::singleProcess
-        (
-            srcMesh_.nCells(),
-            tgtMesh_.nCells()
-        );
-
-    autoPtr<meshToMeshMethod> methodPtr;
-
-    scalar V = 0;
-
-    if (isSingleProcess())
-    {
-        // Do the intersection
-        methodPtr = meshToMeshMethod::New(methodName, srcMesh_, tgtMesh_);
-        V = methodPtr->calculate
-            (
-                srcLocalTgtCells_,
-                srcWeights_,
-                tgtLocalSrcCells_,
-                tgtWeights_
-            );
-
-        // Normalise the weights
-        methodPtr->normalise(srcMesh_, srcLocalTgtCells_, srcWeights_);
-        methodPtr->normalise(tgtMesh_, tgtLocalSrcCells_, tgtWeights_);
-    }
-    else
-    {
-        // Create the target map of overlapping cells. This map gets remote
-        // parts of the target mesh so that everything needed to compute an
-        // intersection is available locally to the source. Use it to create a
-        // source-local target mesh.
-        tgtMapPtr_ =
-            patchToPatchTools::constructDistributionMap
-            (
-                tgtMeshSendCells(srcMesh_, tgtMesh_)
-            );
-        localTgtProcCellsPtr_.reset
-        (
-            new List<remote>
-            (
-                distributeMesh
-                (
-                    tgtMapPtr_(),
-                    tgtMesh_,
-                    localTgtMeshPtr_
-                )
-            )
-        );
-        const polyMesh& localTgtMesh = localTgtMeshPtr_();
-
-        if (debug > 1)
-        {
-            Pout<< "Writing local target mesh: "
-                << localTgtMesh.name() << endl;
-            localTgtMesh.write();
-        }
-
-        // Do the intersection
-        methodPtr = meshToMeshMethod::New(methodName, srcMesh_, localTgtMesh);
-        V = methodPtr->calculate
-            (
-                srcLocalTgtCells_,
-                srcWeights_,
-                tgtLocalSrcCells_,
-                tgtWeights_
-            );
-
-        // Trim the local target mesh
-        trimLocalTgt();
-
-        if (debug > 1)
-        {
-            Pout<< "Writing trimmed local target mesh: "
-                << localTgtMesh.name() << endl;
-            localTgtMesh.write();
-        }
-
-        // Construct the source map
-        srcMapPtr_ =
-            patchToPatchTools::constructDistributionMap
-            (
-                patchToPatchTools::procSendIndices
-                (
-                    tgtLocalSrcCells_,
-                    localTgtProcCellsPtr_()
-                )
-            );
-        localSrcProcCellsPtr_.reset
-        (
-            new List<remote>
-            (
-                patchToPatchTools::distributeAddressing(srcMapPtr_())
-            )
-        );
-
-        // Collect the addressing on the target
-        patchToPatchTools::rDistributeTgtAddressing
-        (
-            tgtMesh_.nCells(),
-            tgtMapPtr_(),
-            localSrcProcCellsPtr_(),
-            tgtLocalSrcCells_
-        );
-
-        // Collect the weights on the target
-        patchToPatchTools::rDistributeListList
-        (
-            tgtMesh_.nCells(),
-            tgtMapPtr_(),
-            tgtWeights_
-        );
-
-        // Normalise the weights
-        methodPtr->normalise(srcMesh_, srcLocalTgtCells_, srcWeights_);
-        methodPtr->normalise(tgtMesh_, tgtLocalSrcCells_, tgtWeights_);
-
-        // collect volume intersection contributions
-        reduce(V, sumOp<scalar>());
-    }
-
-    Info<< "    Overlap volume: " << V << endl;
-
-    return V;
-}
-
-
-void Foam::meshToMesh::calculatePatchToPatches(const word& methodName)
-{
-    if (!srcToTgtPatchToPatches_.empty())
-    {
-        FatalErrorInFunction
-            << "srcToTgtPatchToPatches already calculated"
-            << exit(FatalError);
-    }
-
-    const word& patchToPatchType =
-        meshToMeshMethod::New
-        (
-            methodName,
-            NullObjectRef<polyMesh>(),
-            NullObjectRef<polyMesh>()
-        )->patchToPatchMethod();
-
-    srcToTgtPatchToPatches_.setSize(srcToTgtPatchIDs_.size());
-
-    forAll(srcToTgtPatchIDs_, i)
-    {
-        const label srcPatchi = srcToTgtPatchIDs_[i].first();
-        const label tgtPatchi = srcToTgtPatchIDs_[i].second();
-
-        const polyPatch& srcPP = srcMesh_.boundaryMesh()[srcPatchi];
-        const polyPatch& tgtPP = tgtMesh_.boundaryMesh()[tgtPatchi];
-
-        Info<< "Creating patchToPatch between source patch "
-            << srcPP.name() << " and target patch " << tgtPP.name()
-            << " using " << patchToPatchType << endl;
-
-        Info<< incrIndent;
-
-        srcToTgtPatchToPatches_.set
-        (
-            i,
-            patchToPatch::New(patchToPatchType, true)
-        );
-
-        srcToTgtPatchToPatches_[i].update
-        (
-            srcPP,
-            PatchTools::pointNormals(srcMesh_, srcPP),
-            tgtPP
-        );
-
-        Info<< decrIndent;
-    }
-}
-
-
-void Foam::meshToMesh::constructNoCuttingPatches
 (
-    const word& methodName,
+    const polyMesh& srcMesh,
-    const bool interpAllPatches
+    const polyMesh& tgtMesh,
+    const word& engineType,
+    const HashTable<word>& patchMap
 )
+:
+    srcMesh_(srcMesh),
+    tgtMesh_(tgtMesh),
+    srcToTgtCellsToCells_(),
+    srcToTgtPatchIDs_(),
+    srcToTgtPatchToPatches_()
 {
-    if (interpAllPatches)
+    // If no patch map was supplied, then assume a consistent pair of meshes in
+    // which corresponding patches have the same name
+    if (isNull(patchMap))
     {
         DynamicList<labelPair> srcToTgtPatchIDs;
 
@@ -240,10 +63,18 @@ void Foam::meshToMesh::constructNoCuttingPatches
         {
             const polyPatch& srcPp = srcMesh_.boundaryMesh()[srcPatchi];
 
-            // We want to map all the global patches, including constraint
+            // We don't want to map empty or wedge patches, as by definition
-            // patches (since they might have mappable properties, e.g.
+            // these do not hold relevant values. We also don't want to map
-            // jumpCyclic). We'll fix the value afterwards.
+            // processor patches as these are likely to differ between cases.
-            if (!isA<processorPolyPatch>(srcPp))
+            // In general, though, we do want to map constraint patches as they
+            // might have additional mappable properties; e.g., the jump field
+            // of a jump cyclic.
+            if
+            (
+                !isA<emptyPolyPatch>(srcPp)
+             && !isA<wedgePolyPatch>(srcPp)
+             && !isA<processorPolyPatch>(srcPp)
+            )
             {
                 const label tgtPatchi =
                     tgtMesh_.boundaryMesh().findPatchID(srcPp.name());
@@ -265,21 +96,9 @@ void Foam::meshToMesh::constructNoCuttingPatches
         srcToTgtPatchIDs_.transfer(srcToTgtPatchIDs);
     }
 
-    // calculate patch addressing and weights
+    // If a patch mas was supplied then convert it to pairs of patch indices
-    calculatePatchToPatches(methodName);
+    else
-
+    {
-    // calculate cell addressing and weights
-    calculateCellToCells(methodName);
-}
-
-
-void Foam::meshToMesh::constructFromCuttingPatches
-(
-    const word& methodName,
-    const HashTable<word>& patchMap,
-    const wordList& tgtCuttingPatches
-)
-{
         srcToTgtPatchIDs_.setSize(patchMap.size());
         label i = 0;
         forAllConstIter(HashTable<word>, patchMap, iter)
@@ -287,93 +106,73 @@ void Foam::meshToMesh::constructFromCuttingPatches
             const word& tgtPatchName = iter.key();
             const word& srcPatchName = iter();
 
-        srcToTgtPatchIDs_[i++] =
+            const label srcPatchi =
-            labelPair
+                srcMesh_.boundaryMesh().findPatchID(srcPatchName);
-            (
+            const label tgtPatchi =
-                srcMesh_.boundaryMesh().findPatchID(srcPatchName),
+                tgtMesh_.boundaryMesh().findPatchID(tgtPatchName);
-                tgtMesh_.boundaryMesh().findPatchID(tgtPatchName)
-            );
-    }
 
-    // calculate patch addressing and weights
+            if (srcPatchi == -1)
-    calculatePatchToPatches(methodName);
-
-    // calculate cell addressing and weights
-    calculateCellToCells(methodName);
-
-    // set IDs of cutting patches on target mesh
-    tgtCuttingPatchIDs_.setSize(tgtCuttingPatches.size());
-    forAll(tgtCuttingPatchIDs_, i)
             {
-        const word& patchName = tgtCuttingPatches[i];
+                FatalErrorInFunction
-        tgtCuttingPatchIDs_[i] = tgtMesh_.boundaryMesh().findPatchID(patchName);
+                    << "Patch " << srcPatchName
+                    << " not found in source mesh. "
+                    << "Available source patches are "
+                    << srcMesh_.boundaryMesh().names()
+                    << exit(FatalError);
+            }
+            if (tgtPatchi == -1)
+            {
+                FatalErrorInFunction
+                    << "Patch " << tgtPatchName
+                    << " not found in target mesh. "
+                    << "Available target patches are "
+                    << tgtMesh_.boundaryMesh().names()
+                    << exit(FatalError);
             }
-}
 
+            srcToTgtPatchIDs_[i ++] = labelPair(srcPatchi, tgtPatchi);
+        }
+    }
 
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+    // Calculate cell addressing and weights
+    Info<< "Creating cellsToCells between source mesh "
+        << srcMesh_.name() << " and target mesh " << tgtMesh_.name()
+        << " using " << engineType << endl << incrIndent;
 
-Foam::meshToMesh::meshToMesh
+    srcToTgtCellsToCells_ = cellsToCells::New(engineType);
-(
+    srcToTgtCellsToCells_->update(srcMesh_, tgtMesh_);
-    const polyMesh& src,
+
-    const polyMesh& tgt,
+    Info<< decrIndent;
-    const word& methodName,
+
-    bool interpAllPatches
+    // Calculate patch addressing and weights
-)
+    srcToTgtPatchToPatches_.setSize(srcToTgtPatchIDs_.size());
-:
+    forAll(srcToTgtPatchIDs_, i)
-    srcMesh_(src),
+    {
-    tgtMesh_(tgt),
+        const label srcPatchi = srcToTgtPatchIDs_[i].first();
-    srcToTgtPatchIDs_(),
+        const label tgtPatchi = srcToTgtPatchIDs_[i].second();
-    srcToTgtPatchToPatches_(),
+
-    tgtCuttingPatchIDs_(),
+        const polyPatch& srcPP = srcMesh_.boundaryMesh()[srcPatchi];
-    srcLocalTgtCells_(),
+        const polyPatch& tgtPP = tgtMesh_.boundaryMesh()[tgtPatchi];
-    tgtLocalSrcCells_(),
+
-    srcWeights_(),
+        Info<< "Creating patchToPatch between source patch "
-    tgtWeights_(),
+            << srcPP.name() << " and target patch " << tgtPP.name()
-    singleProcess_(-1),
+            << " using " << engineType << endl << incrIndent;
-    srcMapPtr_(nullptr),
+
-    tgtMapPtr_(nullptr),
+        srcToTgtPatchToPatches_.set
-    localSrcProcCellsPtr_(nullptr),
-    localTgtProcCellsPtr_(nullptr),
-    localTgtMeshPtr_(nullptr)
-{
-    constructNoCuttingPatches
         (
-        methodName,
+            i,
-        interpAllPatches
+            patchToPatch::New(engineType, true)
         );
-}
 
-
+        srcToTgtPatchToPatches_[i].update
-Foam::meshToMesh::meshToMesh
-(
-    const polyMesh& src,
-    const polyMesh& tgt,
-    const word& methodName,
-    const HashTable<word>& patchMap,
-    const wordList& tgtCuttingPatches
-)
-:
-    srcMesh_(src),
-    tgtMesh_(tgt),
-    srcToTgtPatchIDs_(),
-    srcToTgtPatchToPatches_(),
-    tgtCuttingPatchIDs_(),
-    srcLocalTgtCells_(),
-    tgtLocalSrcCells_(),
-    srcWeights_(),
-    tgtWeights_(),
-    singleProcess_(-1),
-    srcMapPtr_(nullptr),
-    tgtMapPtr_(nullptr),
-    localTgtMeshPtr_(nullptr)
-{
-    constructFromCuttingPatches
         (
-        methodName,
+            srcPP,
-        patchMap,
+            PatchTools::pointNormals(srcMesh_, srcPP),
-        tgtCuttingPatches
+            tgtPP
         );
+
+        Info<< decrIndent;
+    }
 }
 
 
@@ -385,29 +184,65 @@ Foam::meshToMesh::~meshToMesh()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+bool Foam::meshToMesh::consistent() const
+{
+    boolList srcPatchIsMapped(srcMesh_.boundaryMesh().size(), false);
+    boolList tgtPatchIsMapped(tgtMesh_.boundaryMesh().size(), false);
+
+    // Mark anything paired as mapped
+    forAll(srcToTgtPatchIDs_, i)
+    {
+        const label srcPatchi = srcToTgtPatchIDs_[i].first();
+        const label tgtPatchi = srcToTgtPatchIDs_[i].second();
+
+        srcPatchIsMapped[srcPatchi] = true;
+        tgtPatchIsMapped[tgtPatchi] = true;
+    }
+
+    // Filter out un-mappable patches
+    forAll(srcMesh_.boundaryMesh(), srcPatchi)
+    {
+        const polyPatch& srcPp = srcMesh_.boundaryMesh()[srcPatchi];
+
+        if
+        (
+            isA<emptyPolyPatch>(srcPp)
+         || isA<wedgePolyPatch>(srcPp)
+         || isA<processorPolyPatch>(srcPp)
+        )
+        {
+            srcPatchIsMapped[srcPp.index()] = true;
+        }
+    }
+    forAll(tgtMesh_.boundaryMesh(), tgtPatchi)
+    {
+        const polyPatch& tgtPp = tgtMesh_.boundaryMesh()[tgtPatchi];
+
+        if
+        (
+            isA<emptyPolyPatch>(tgtPp)
+         || isA<wedgePolyPatch>(tgtPp)
+         || isA<processorPolyPatch>(tgtPp)
+        )
+        {
+            tgtPatchIsMapped[tgtPp.index()] = true;
+        }
+    }
+
+    // Return whether or not everything is mapped
+    return
+        findIndex(srcPatchIsMapped, false) == -1
+     && findIndex(tgtPatchIsMapped, false) == -1;
+}
+
+
 Foam::remote Foam::meshToMesh::srcToTgtPoint
 (
     const label srcCelli,
     const point& p
 ) const
 {
-    forAll(srcLocalTgtCells_[srcCelli], i)
+    return srcToTgtCellsToCells_().srcToTgtPoint(tgtMesh_, srcCelli, p);
-    {
-        const label tgtCelli = srcLocalTgtCells_[srcCelli][i];
-
-        const polyMesh& tgtMesh =
-            singleProcess_ == -1 ? localTgtMeshPtr_() : tgtMesh_;
-
-        if (tgtMesh.pointInCell(p, tgtCelli))
-        {
-            return
-                singleProcess_ == -1
-              ? localTgtProcCellsPtr_()[tgtCelli]
-              : remote(Pstream::myProcNo(), tgtCelli);
-        }
-    }
-
-    return remote();
 }
 
 

src/meshTools/meshToMesh/meshToMesh.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2012-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -25,17 +25,11 @@ Class
     Foam::meshToMesh
 
 Description
-    Class to calculate the cell-addressing between two overlapping meshes
+    Class to calculate interpolative addressing and weights between the cells
-
+    and patches of two overlapping meshes
-    Mapping is performed using a run-time selectable interpolation mothod
-
-See also
-    meshToMeshMethod
 
 SourceFiles
     meshToMesh.C
-    meshToMeshParallelOps.C
-    meshToMeshTemplates.C
 
 \*---------------------------------------------------------------------------*/
 
@@ -43,10 +37,8 @@ SourceFiles
 #define meshToMesh_H
 
 #include "polyMesh.H"
-#include "boundBox.H"
-#include "distributionMap.H"
-#include "NamedEnum.H"
 #include "patchToPatch.H"
+#include "cellsToCells.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -67,6 +59,9 @@ class meshToMesh
         //- Reference to the target mesh
         const polyMesh& tgtMesh_;
 
+        //- Interpolation engine between source and target cells
+        autoPtr<cellsToCells> srcToTgtCellsToCells_;
+
         //- List of corresponding source and target patches that are to be
         //  mapped to each other
         List<labelPair> srcToTgtPatchIDs_;
@@ -75,93 +70,6 @@ class meshToMesh
         //  target patches
         PtrList<patchToPatch> srcToTgtPatchToPatches_;
 
-        //- Cutting patches whose values are set using a zero-gradient condition
-        labelList tgtCuttingPatchIDs_;
-
-        //- For each source cell, the coupled local target cells
-        labelListList srcLocalTgtCells_;
-
-        //- For each target cell, the coupled local source cells
-        labelListList tgtLocalSrcCells_;
-
-        //- For each source cell, the coupled target weights
-        scalarListList srcWeights_;
-
-        //- For each target cell, the coupled source weights
-        scalarListList tgtWeights_;
-
-        //- Index of processor that holds all of both sides, or -1
-        label singleProcess_;
-
-        //- Map from source patch cells to target-local source patch cells
-        autoPtr<distributionMap> srcMapPtr_;
-
-        //- Map from target patch cells to source-local target patch cells
-        autoPtr<distributionMap> tgtMapPtr_;
-
-        //- When running in parallel, a map from local source cell index to
-        //  source processor and cell index
-        autoPtr<List<remote>> localSrcProcCellsPtr_;
-
-        //- When running in parallel, a map from local target cell index to
-        //  target processor and cell index
-        autoPtr<List<remote>> localTgtProcCellsPtr_;
-
-        //- The target mesh, distributed locally to the source
-        autoPtr<polyMesh> localTgtMeshPtr_;
-
-
-    // Private Member Functions
-
-        //- Helper function to add a constant offset to a list
-        template<class Type>
-        static void add(UList<Type>& fld, const label offset);
-
-        //- Calculate the cell intersections. Returns the overlap volume.
-        scalar calculateCellToCells(const word& methodName);
-
-        //- Calculate patch intersections
-        void calculatePatchToPatches(const word& patchToPatchType);
-
-        //- Constructor helper
-        void constructNoCuttingPatches
-        (
-            const word& methodName,
-            const bool interpAllPatches
-        );
-
-        //- Constructor helper
-        void constructFromCuttingPatches
-        (
-            const word& methodName,
-            const HashTable<word>& patchMap,
-            const wordList& tgtCuttingPatches
-        );
-
-
-        // Parallel operations
-
-            //- Determine which target cells need to be sent to the source.
-            //  This is done before intersection. Bound boxes are used to
-            //  estimate what cells will intersect.
-            labelListList tgtMeshSendCells
-            (
-                const polyMesh& srcMesh,
-                const polyMesh& tgtMesh
-            ) const;
-
-            //- Distribute a mesh given its distribution map
-            static List<remote> distributeMesh
-            (
-                const distributionMap& map,
-                const polyMesh& mesh,
-                autoPtr<polyMesh>& localMeshPtr
-            );
-
-            //- Trim the local target addressing and mesh so that communication
-            //  from the target to the source is optimised
-            void trimLocalTgt();
-
 
 protected:
 
@@ -169,6 +77,9 @@ protected:
 
         // Access
 
+            //- Return the interpolation engine between source and target cells
+            inline const cellsToCells& srcToTgtCellsToCells() const;
+
             //- Return the source patch indices
             inline const List<labelPair>& srcToTgtPatchIDs() const;
 
@@ -176,9 +87,6 @@ protected:
             //  source and target patches
             inline const PtrList<patchToPatch>& srcToTgtPatchToPatches() const;
 
-            //- Return the cutting patch indices
-            inline const labelList& tgtCuttingPatchIDs() const;
-
 
 public:
 
@@ -188,23 +96,15 @@ public:
 
     // Constructors
 
-        //- Construct from source and target meshes, generic mapping methods
+        //- Construct from source and target meshes. If a patchMap is supplied,
+        //  then map between the specified patches. If not, then assume a
+        //  consistent mesh and map all patches 1-to-1.
         meshToMesh
         (
-            const polyMesh& src,
+            const polyMesh& srcMesh,
-            const polyMesh& tgt,
+            const polyMesh& tgtMesh,
-            const word& methodName,
+            const word& engineType,
-            const bool interpAllPatches = true
+            const HashTable<word>& patchMap = NullObjectRef<HashTable<word>>()
-        );
-
-        //- Construct from source and target meshes, generic mapping methods
-        meshToMesh
-        (
-            const polyMesh& src,
-            const polyMesh& tgt,
-            const word& methodName,
-            const HashTable<word>& patchMap,
-            const wordList& cuttingPatches
         );
 
         //- Disallow default bitwise copy construction
@@ -225,63 +125,16 @@ public:
             //- Return const access to the target mesh
             inline const polyMesh& tgtMesh() const;
 
-            //- Index of the processor holding all cells of the meshToMesh,
+            //- Is the map between consistent meshes? I.e., are all
-            //  or -1 if spread across multiple processors
+            //  (non-processor) patches mapped one-to-one?
-            inline label singleProcess() const;
+            bool consistent() const;
-
-            //- Is this intersection on a single process?
-            inline bool isSingleProcess() const;
-
-
-        // Evaluation
-
-            // Source-to-target field mapping
-
-                //- Map field from src to tgt mesh. Values passed in via
-                //  'result' are used to initialise the return value.
-                template<class Type>
-                void mapSrcToTgt
-                (
-                    const UList<Type>& srcFld,
-                    List<Type>& result
-                ) const;
-
-                //- Return the src field mapped to the tgt mesh. Initial values
-                //  of the result are set to zero.
-                template<class Type>
-                tmp<Field<Type>> mapSrcToTgt(const Field<Type>& srcFld) const;
-
-
-            // Target-to-source field mapping
-
-                //- Map field from tgt to src mesh. Values passed in via
-                //  'result' are used to initialise the return value.
-                template<class Type>
-                void mapTgtToSrc
-                (
-                    const UList<Type>& tgtFld,
-                    List<Type>& result
-                ) const;
-
-                //- Return the tgt field mapped to the src mesh. Initial values
-                //  of the result are set to zero.
-                template<class Type>
-                tmp<Field<Type>> mapTgtToSrc(const Field<Type>& tgtFld) const;
 
 
         // Source-to-target point finding
 
-                //- Find the target processor and cell associated with a point
+            //- Find the target processor and cell associated with a point in a
-                //  in a source cell. Note that this will only work with
+            //  source cell. See cellsToCells::srcToTgtPoint.
-                //  methods that fill a cell's stencil with everything that
+            remote srcToTgtPoint(const label srcCelli, const point& p) const;
-                //  overlaps that cell. At present this is just
-                //  cellVolumeWeightMethod, but we might add a cheaper
-                //  bound-box based method like patchToPatches::rays in future.
-                remote srcToTgtPoint
-                (
-                    const label srcCelli,
-                    const point& p
-                ) const;
 
 
     // Member Operators
@@ -301,12 +154,6 @@ public:
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-#ifdef NoRepository
-    #include "meshToMeshTemplates.C"
-#endif
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
 #endif
 
 // ************************************************************************* //

src/meshTools/meshToMesh/meshToMeshI.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2012-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2012-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -27,6 +27,12 @@ License
 
 // * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
+inline const Foam::cellsToCells& Foam::meshToMesh::srcToTgtCellsToCells() const
+{
+    return srcToTgtCellsToCells_();
+}
+
+
 inline const Foam::List<Foam::labelPair>&
 Foam::meshToMesh::srcToTgtPatchIDs() const
 {
@@ -41,12 +47,6 @@ Foam::meshToMesh::srcToTgtPatchToPatches() const
 }
 
 
-inline const Foam::labelList& Foam::meshToMesh::tgtCuttingPatchIDs() const
-{
-    return tgtCuttingPatchIDs_;
-}
-
-
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
 inline const Foam::polyMesh& Foam::meshToMesh::srcMesh() const
@@ -61,16 +61,4 @@ inline const Foam::polyMesh& Foam::meshToMesh::tgtMesh() const
 }
 
 
-inline Foam::label Foam::meshToMesh::singleProcess() const
-{
-    return singleProcess_;
-}
-
-
-inline bool Foam::meshToMesh::isSingleProcess() const
-{
-    return singleProcess_ != -1;
-}
-
-
 // ************************************************************************* //

src/meshTools/meshToMesh/meshToMeshTemplates.C

@@ -1,200 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2012-2022 OpenFOAM Foundation
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "meshToMesh.H"
-
-// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
-
-template<class Type>
-void Foam::meshToMesh::add
-(
-    UList<Type>& fld,
-    const label offset
-)
-{
-    forAll(fld, i)
-    {
-        fld[i] += offset;
-    }
-}
-
-
-template<class Type>
-void Foam::meshToMesh::mapSrcToTgt
-(
-    const UList<Type>& srcField,
-    List<Type>& result
-) const
-{
-    if (result.size() != tgtLocalSrcCells_.size())
-    {
-        FatalErrorInFunction
-            << "Supplied field size is not equal to target mesh size" << nl
-            << "    source mesh    = " << srcLocalTgtCells_.size() << nl
-            << "    target mesh    = " << tgtLocalSrcCells_.size() << nl
-            << "    supplied field = " << result.size()
-            << abort(FatalError);
-    }
-
-    if (!isSingleProcess())
-    {
-        const distributionMap& map = srcMapPtr_();
-
-        List<Type> work(srcField);
-        map.distribute(work);
-
-        forAll(result, tgtCelli)
-        {
-            if (tgtLocalSrcCells_[tgtCelli].size())
-            {
-                result[tgtCelli] *= (1.0 - sum(tgtWeights_[tgtCelli]));
-                forAll(tgtLocalSrcCells_[tgtCelli], i)
-                {
-                    result[tgtCelli] +=
-                        tgtWeights_[tgtCelli][i]
-                       *work[tgtLocalSrcCells_[tgtCelli][i]];
-                }
-            }
-        }
-    }
-    else
-    {
-        forAll(result, tgtCelli)
-        {
-            if (tgtLocalSrcCells_[tgtCelli].size())
-            {
-                result[tgtCelli] *= (1.0 - sum(tgtWeights_[tgtCelli]));
-                forAll(tgtLocalSrcCells_[tgtCelli], i)
-                {
-                    result[tgtCelli] +=
-                        tgtWeights_[tgtCelli][i]
-                       *srcField[tgtLocalSrcCells_[tgtCelli][i]];
-                }
-            }
-        }
-    }
-}
-
-
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::meshToMesh::mapSrcToTgt
-(
-    const Field<Type>& srcField
-) const
-{
-    tmp<Field<Type>> tresult
-    (
-        new Field<Type>
-        (
-            tgtLocalSrcCells_.size(),
-            Zero
-        )
-    );
-
-    mapSrcToTgt(srcField, tresult.ref());
-
-    return tresult;
-}
-
-
-template<class Type>
-void Foam::meshToMesh::mapTgtToSrc
-(
-    const UList<Type>& tgtField,
-    List<Type>& result
-) const
-{
-    if (result.size() != srcLocalTgtCells_.size())
-    {
-        FatalErrorInFunction
-            << "Supplied field size is not equal to source mesh size" << nl
-            << "    source mesh    = " << srcLocalTgtCells_.size() << nl
-            << "    target mesh    = " << tgtLocalSrcCells_.size() << nl
-            << "    supplied field = " << result.size()
-            << abort(FatalError);
-    }
-
-    if (!isSingleProcess())
-    {
-        const distributionMap& map = tgtMapPtr_();
-
-        List<Type> work(tgtField);
-        map.distribute(work);
-
-        forAll(result, srcCelli)
-        {
-            if (srcLocalTgtCells_[srcCelli].size())
-            {
-                result[srcCelli] *= (1.0 - sum(srcWeights_[srcCelli]));
-                forAll(srcLocalTgtCells_[srcCelli], i)
-                {
-                    result[srcCelli] +=
-                        srcWeights_[srcCelli][i]
-                       *work[srcLocalTgtCells_[srcCelli][i]];
-                }
-            }
-        }
-    }
-    else
-    {
-        forAll(result, srcCelli)
-        {
-            if (srcLocalTgtCells_[srcCelli].size())
-            {
-                result[srcCelli] *= (1.0 - sum(srcWeights_[srcCelli]));
-                forAll(srcLocalTgtCells_[srcCelli], i)
-                {
-                    result[srcCelli] +=
-                        srcWeights_[srcCelli][i]
-                       *tgtField[srcLocalTgtCells_[srcCelli][i]];
-                }
-            }
-        }
-    }
-}
-
-
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::meshToMesh::mapTgtToSrc
-(
-    const Field<Type>& tgtField
-) const
-{
-    tmp<Field<Type>> tresult
-    (
-        new Field<Type>
-        (
-            srcLocalTgtCells_.size(),
-            Zero
-        )
-    );
-
-    mapTgtToSrc(tgtField, tresult.ref());
-
-    return tresult;
-}
-
-
-// ************************************************************************* //

src/meshTools/patchToPatch/intersection/intersectionPatchToPatch.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2021-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2021-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -75,7 +75,7 @@ public:
             part()
             :
                 area(Zero),
-                centre(NaN<point>())
+                centre(patchToPatchTools::NaN<point>())
             {}
 
             //- Default construct

src/meshTools/patchToPatch/patchToPatch/patchToPatch.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -30,16 +30,17 @@ Description
 SourceFiles
     patchToPatch.C
     patchToPatchParallelOps.C
+    patchToPatchTemplates.C
 
 \*---------------------------------------------------------------------------*/
 
 #ifndef patchToPatch_H
 #define patchToPatch_H
 
+#include "remote.H"
 #include "distributionMap.H"
 #include "primitivePatch.H"
 #include "primitiveOldTimePatch.H"
-#include "remote.H"
 #include "runTimeSelectionTables.H"
 #include "treeBoundBox.H"
 
@@ -254,31 +255,6 @@ protected:
             //- For each target face, the coupled source weights
             virtual tmpNrc<List<DynamicList<scalar>>> tgtWeights() const = 0;
 
-            //- Return a primitive with all components set to NaN
-            template<class Type>
-            static Type NaN();
-
-            //- Interpolate with normalisation
-            template<class Type>
-            static tmp<Field<Type>> interpolate
-            (
-                const List<DynamicList<label>>& localOtherFaces,
-                const List<DynamicList<scalar>>& weights,
-                const autoPtr<distributionMap>& otherMapPtr,
-                const Field<Type>& otherFld
-            );
-
-            //- Interpolate without normalisation
-            template<class Type>
-            static tmp<Field<Type>> interpolate
-            (
-                const List<DynamicList<label>>& localOtherFaces,
-                const List<DynamicList<scalar>>& weights,
-                const autoPtr<distributionMap>& otherMapPtr,
-                const Field<Type>& otherFld,
-                const Field<Type>& leftOverFld
-            );
-
 
 public:
 

src/meshTools/patchToPatch/patchToPatch/patchToPatchParallelOps.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -23,9 +23,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "autoPtr.H"
 #include "patchToPatch.H"
-#include "treeBoundBoxList.H"
 #include "uindirectPrimitivePatch.H"
 #include "uindirectPrimitiveOldTimePatch.H"
 
@@ -40,11 +38,11 @@ Foam::labelListList Foam::patchToPatch::tgtPatchSendFaces
 ) const
 {
     // Get the bound boxes for the source patch. Just a single box for now.
-    List<treeBoundBoxList> srcPatchProcBbs(Pstream::nProcs());
+    List<List<treeBoundBox>> srcPatchProcBbs(Pstream::nProcs());
     if (srcPatch.size())
     {
         srcPatchProcBbs[Pstream::myProcNo()] =
-            treeBoundBoxList
+            List<treeBoundBox>
             (
                 1,
                 srcBox(srcPatch, srcPointNormals, srcPointNormals0)
@@ -52,7 +50,7 @@ Foam::labelListList Foam::patchToPatch::tgtPatchSendFaces
     }
     else
     {
-        srcPatchProcBbs[Pstream::myProcNo()] = treeBoundBoxList();
+        srcPatchProcBbs[Pstream::myProcNo()] = List<treeBoundBox>();
     }
 
     // Distribute the boxes

src/meshTools/patchToPatch/patchToPatch/patchToPatchTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -24,111 +24,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "patchToPatch.H"
-
+#include "patchToPatchTools.H"
-// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
-
-template<class Type>
-Type Foam::patchToPatch::NaN()
-{
-    Type result;
-
-    for (direction cmpt = 0; cmpt < pTraits<Type>::nComponents; cmpt++)
-    {
-        setComponent(result, cmpt) = Foam::NaN;
-    }
-
-    return result;
-}
-
-
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::patchToPatch::interpolate
-(
-    const List<DynamicList<label>>& localOtherFaces,
-    const List<DynamicList<scalar>>& weights,
-    const autoPtr<distributionMap>& otherMapPtr,
-    const Field<Type>& otherFld
-)
-{
-    // Distribute the other field if necessary
-    tmp<Field<Type>> tLocalOtherFld;
-    if (otherMapPtr.valid())
-    {
-        tLocalOtherFld = tmp<Field<Type>>(new Field<Type>(otherFld));
-        otherMapPtr->distribute(tLocalOtherFld.ref());
-    }
-    const Field<Type>& localOtherFld =
-        otherMapPtr.valid() ? tLocalOtherFld() : otherFld;
-
-    // Allocate the result
-    tmp<Field<Type>> tFld(new Field<Type>(localOtherFaces.size(), NaN<Type>()));
-    Field<Type>& fld = tFld.ref();
-
-    // Compute the result as a weighted sum
-    forAll(localOtherFaces, facei)
-    {
-        scalar sumW = 0;
-        Type sumWF = Zero;
-
-        forAll(localOtherFaces[facei], i)
-        {
-            const scalar w = weights[facei][i];
-            sumW += w;
-            sumWF += w*localOtherFld[localOtherFaces[facei][i]];
-        }
-
-        if (localOtherFaces[facei].size())
-        {
-            fld[facei] = sumWF/sumW;
-        }
-    }
-
-    return tFld;
-}
-
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::patchToPatch::interpolate
-(
-    const List<DynamicList<label>>& localOtherFaces,
-    const List<DynamicList<scalar>>& weights,
-    const autoPtr<distributionMap>& otherMapPtr,
-    const Field<Type>& otherFld,
-    const Field<Type>& leftOverFld
-)
-{
-    // Distribute the other field if necessary
-    tmp<Field<Type>> tLocalOtherFld;
-    if (otherMapPtr.valid())
-    {
-        tLocalOtherFld = tmp<Field<Type>>(new Field<Type>(otherFld));
-        otherMapPtr->distribute(tLocalOtherFld.ref());
-    }
-    const Field<Type>& localOtherFld =
-        otherMapPtr.valid() ? tLocalOtherFld() : otherFld;
-
-    // Allocate the result
-    tmp<Field<Type>> tFld(new Field<Type>(localOtherFaces.size(), NaN<Type>()));
-    Field<Type>& fld = tFld.ref();
-
-    // Compute the result as a weighted sum
-    forAll(localOtherFaces, facei)
-    {
-        scalar sumW = 0;
-        Type sumWF = Zero;
-
-        forAll(localOtherFaces[facei], i)
-        {
-            const scalar w = weights[facei][i];
-            sumW += w;
-            sumWF += w*localOtherFld[localOtherFaces[facei][i]];
-        }
-
-        fld[facei] = sumWF + (1 - sumW)*leftOverFld[facei];
-    }
-
-    return tFld;
-}
-
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
@@ -137,10 +33,10 @@ Foam::tmp<Foam::Field<Type>>
 Foam::patchToPatch::srcToTgt(const Field<Type>& srcFld) const
 {
     return
-        interpolate
+        patchToPatchTools::interpolate
         (
             tgtLocalSrcFaces_,
-            tgtWeights(),
+            tgtWeights()(),
             srcMapPtr_,
             srcFld
         );
@@ -155,10 +51,10 @@ Foam::tmp<Foam::Field<Type>> Foam::patchToPatch::srcToTgt
 ) const
 {
     return
-        interpolate
+        patchToPatchTools::interpolate
         (
             tgtLocalSrcFaces_,
-            tgtWeights(),
+            tgtWeights()(),
             srcMapPtr_,
             srcFld,
             leftOverTgtFld
@@ -171,10 +67,10 @@ Foam::tmp<Foam::Field<Type>>
 Foam::patchToPatch::tgtToSrc(const Field<Type>& tgtFld) const
 {
     return
-        interpolate
+        patchToPatchTools::interpolate
         (
             srcLocalTgtFaces_,
-            srcWeights(),
+            srcWeights()(),
             tgtMapPtr_,
             tgtFld
         );
@@ -189,10 +85,10 @@ Foam::tmp<Foam::Field<Type>> Foam::patchToPatch::tgtToSrc
 ) const
 {
     return
-        interpolate
+        patchToPatchTools::interpolate
         (
             srcLocalTgtFaces_,
-            srcWeights(),
+            srcWeights()(),
             tgtMapPtr_,
             tgtFld,
             leftOverSrcFld

src/meshTools/patchToPatchTools/patchToPatchTools.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -137,6 +137,31 @@ void rDistributeTgtAddressing
     List<DynamicList<label>>& tgtLocalSrcFaces
 );
 
+//- Return a primitive with all components set to NaN
+template<class Type>
+static Type NaN();
+
+//- Interpolate with normalisation
+template<class Type, class LabelList, class ScalarList>
+static tmp<Field<Type>> interpolate
+(
+    const List<LabelList>& localOtherFaces,
+    const List<ScalarList>& weights,
+    const autoPtr<distributionMap>& otherMapPtr,
+    const Field<Type>& otherFld
+);
+
+//- Interpolate without normalisation
+template<class Type, class LabelList, class ScalarList>
+static tmp<Field<Type>> interpolate
+(
+    const List<LabelList>& localOtherFaces,
+    const List<ScalarList>& weights,
+    const autoPtr<distributionMap>& otherMapPtr,
+    const Field<Type>& otherFld,
+    const Field<Type>& leftOverFld
+);
+
 } // End namespace patchToPatchTools
 } // End namespace Foam
 

src/meshTools/patchToPatchTools/patchToPatchToolsTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2022 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2022-2023 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -82,4 +82,108 @@ void Foam::patchToPatchTools::rDistributeListList
 }
 
 
+template<class Type>
+Type Foam::patchToPatchTools::NaN()
+{
+    Type result;
+
+    for (direction cmpt = 0; cmpt < pTraits<Type>::nComponents; cmpt++)
+    {
+        setComponent(result, cmpt) = Foam::NaN;
+    }
+
+    return result;
+}
+
+
+template<class Type, class LabelList, class ScalarList>
+Foam::tmp<Foam::Field<Type>> Foam::patchToPatchTools::interpolate
+(
+    const List<LabelList>& localOtherFaces,
+    const List<ScalarList>& weights,
+    const autoPtr<distributionMap>& otherMapPtr,
+    const Field<Type>& otherFld
+)
+{
+    // Distribute the other field if necessary
+    tmp<Field<Type>> tLocalOtherFld;
+    if (otherMapPtr.valid())
+    {
+        tLocalOtherFld = tmp<Field<Type>>(new Field<Type>(otherFld));
+        otherMapPtr->distribute(tLocalOtherFld.ref());
+    }
+    const Field<Type>& localOtherFld =
+        otherMapPtr.valid() ? tLocalOtherFld() : otherFld;
+
+    // Allocate the result
+    tmp<Field<Type>> tFld(new Field<Type>(localOtherFaces.size(), NaN<Type>()));
+    Field<Type>& fld = tFld.ref();
+
+    // Compute the result as a weighted sum
+    forAll(localOtherFaces, facei)
+    {
+        scalar sumW = 0;
+        Type sumWF = Zero;
+
+        forAll(localOtherFaces[facei], i)
+        {
+            const scalar w = weights[facei][i];
+            sumW += w;
+            sumWF += w*localOtherFld[localOtherFaces[facei][i]];
+        }
+
+        if (localOtherFaces[facei].size())
+        {
+            fld[facei] = sumWF/sumW;
+        }
+    }
+
+    return tFld;
+}
+
+
+template<class Type, class LabelList, class ScalarList>
+Foam::tmp<Foam::Field<Type>> Foam::patchToPatchTools::interpolate
+(
+    const List<LabelList>& localOtherFaces,
+    const List<ScalarList>& weights,
+    const autoPtr<distributionMap>& otherMapPtr,
+    const Field<Type>& otherFld,
+    const Field<Type>& leftOverFld
+)
+{
+    // Distribute the other field if necessary
+    tmp<Field<Type>> tLocalOtherFld;
+    if (otherMapPtr.valid())
+    {
+        tLocalOtherFld = tmp<Field<Type>>(new Field<Type>(otherFld));
+        otherMapPtr->distribute(tLocalOtherFld.ref());
+    }
+    const Field<Type>& localOtherFld =
+        otherMapPtr.valid() ? tLocalOtherFld() : otherFld;
+
+    // Allocate the result
+    tmp<Field<Type>> tFld(new Field<Type>(localOtherFaces.size(), NaN<Type>()));
+    Field<Type>& fld = tFld.ref();
+
+    // Compute the result as a weighted sum
+    forAll(localOtherFaces, facei)
+    {
+        scalar sumW = 0;
+        Type sumWF = Zero;
+
+        forAll(localOtherFaces[facei], i)
+        {
+            const scalar w = weights[facei][i];
+            sumW += w;
+            sumWF += w*localOtherFld[localOtherFaces[facei][i]];
+        }
+
+        fld[facei] = sumWF + (1 - sumW)*leftOverFld[facei];
+    }
+
+    return tFld;
+}
+
+
 // ************************************************************************* //

tutorials/modules/CHT/heatExchanger/constant/air/fvModels

@@ -21,7 +21,7 @@ airToporous
     nbrRegion       porous;
     master          false;
 
-    interpolationMethod cellVolumeWeight;
+    interpolationMethod intersection;
 
     semiImplicit    no;
 }
@@ -34,7 +34,7 @@ porosityBlockage
     {
         nbrRegion       porous;
 
-        interpolationMethod cellVolumeWeight;
+        interpolationMethod intersection;
 
         type            DarcyForchheimer;
 

tutorials/modules/CHT/heatExchanger/constant/porous/fvModels

@@ -21,7 +21,7 @@ porousToair
     nbrRegion       air;
     master          true;
 
-    interpolationMethod cellVolumeWeight;
+    interpolationMethod intersection;
 
     semiImplicit    no;