ENH: snappyHexMesh: handle parallel cyclics. Fixes #1731.

src/mesh/snappyHexMesh/Make/files

@@ -17,6 +17,7 @@ meshRefinement/meshRefinementGapRefine.C
 meshRefinement/meshRefinementBlock.C
 meshRefinement/wallPoints.C
 meshRefinement/patchFaceOrientation.C
+meshRefinement/weightedPosition.C
 
 refinementFeatures/refinementFeatures.C
 refinementSurfaces/surfaceZonesInfo.C

src/mesh/snappyHexMesh/meshRefinement/meshRefinementProblemCells.C

@@ -1093,7 +1093,7 @@ Foam::labelList Foam::meshRefinement::markFacesOnProblemCellsGeometric
             newPoints[meshPoints[i]] += disp[i];
         }
 
-        syncTools::syncPointList
+        syncTools::syncPointPositions
         (
             mesh_,
             newPoints,

src/mesh/snappyHexMesh/meshRefinement/weightedPosition.C

@@ -0,0 +1,153 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2020 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+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 "weightedPosition.H"
+#include "vectorTensorTransform.H"
+#include "coupledPolyPatch.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+const Foam::weightedPosition Foam::pTraits<Foam::weightedPosition>::zero
+(
+    scalar(0),
+    Foam::point::zero
+);
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::weightedPosition::weightedPosition()
+:
+    Tuple2<scalar, point>()
+{}
+
+
+Foam::weightedPosition::weightedPosition(const scalar s, const point& p)
+:
+    Tuple2<scalar, point>(s, p)
+{}
+
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+void Foam::weightedPosition::getPoints
+(
+    const UList<weightedPosition>& in,
+    List<point>& out
+)
+{
+    out.setSize(in.size());
+    forAll(in, i)
+    {
+        out[i] = in[i].second();
+
+        if (mag(in[i].first()) > VSMALL)
+        {
+            out[i] /= in[i].first();
+        }
+    }
+}
+
+
+void Foam::weightedPosition::setPoints
+(
+    const UList<point>& in,
+    List<weightedPosition>& out
+)
+{
+    out.setSize(in.size());
+    forAll(in, i)
+    {
+        out[i].second() = out[i].first()*in[i];
+    }
+}
+
+
+void Foam::weightedPosition::plusEqOp
+(
+    weightedPosition& x,
+    const weightedPosition& y
+)
+{
+    x.first() += y.first();
+    x.second() += y.second();
+}
+
+
+void Foam::weightedPosition::operator()
+(
+    const vectorTensorTransform& vt,
+    const bool forward,
+    List<weightedPosition>& fld
+) const
+{
+    pointField pfld;
+    getPoints(fld, pfld);
+
+    if (forward)
+    {
+        pfld = vt.transformPosition(pfld);
+    }
+    else
+    {
+        pfld = vt.invTransformPosition(pfld);
+    }
+
+    setPoints(pfld, fld);
+}
+
+
+void Foam::weightedPosition::operator()
+(
+    const vectorTensorTransform& vt,
+    const bool forward,
+    List<List<weightedPosition>>& flds
+) const
+{
+    for (List<weightedPosition>& fld : flds)
+    {
+        operator()(vt, forward, fld);
+    }
+}
+
+
+void Foam::weightedPosition::operator()
+(
+    const coupledPolyPatch& cpp,
+    Field<weightedPosition>& fld
+) const
+{
+    pointField pfld;
+    getPoints(fld, pfld);
+
+    cpp.transformPosition(pfld);
+
+    setPoints(pfld, fld);
+}
+
+
+// ************************************************************************* //

src/mesh/snappyHexMesh/meshRefinement/weightedPosition.H

@@ -0,0 +1,180 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2020 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+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::weightedPosition
+
+Description
+    Wrapper for position + weight to be used in e.g. averaging.
+
+    This avoids the problems when synchronising locations with e.g.
+    parallel cyclics. The separation vector only applies to locations
+    and not e.g. summed locations. Note that there is no corresponding
+    problem for rotational cyclics.
+
+    Typical use might be to e.g. average face centres to points on a patch
+
+    const labelListList& pointFaces = pp.pointFaces();
+    const pointField& faceCentres = pp.faceCentres();
+
+    Field<weightedPosition> avgBoundary(pointFaces.size());
+
+    forAll(pointFaces, pointi)
+    {
+        const labelList& pFaces = pointFaces[pointi];
+        avgBoundary[pointi].first() = pFaces.size();
+        avgBoundary[pointi].second() = sum(pointField(faceCentres, pFaces));
+    }
+    syncTools::syncPointList
+    (
+        mesh,
+        pp.meshPoints(),
+        avgBoundary,
+        weightedPosition::plusEqOp,     // combine op
+        pTraits<weightedPosition>::zero,// null value (not used)
+        pTraits<weightedPosition>::zero // transform class
+    );
+
+
+SourceFiles
+    weightedPosition.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef weightedPosition_H
+#define weightedPosition_H
+
+#include "Tuple2.H"
+#include "point.H"
+#include "Field.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward declarations
+class weightedPosition;
+class vectorTensorTransform;
+class coupledPolyPatch;
+
+//- pTraits
+template<>
+class pTraits<weightedPosition>
+{
+public:
+    typedef weightedPosition cmptType;
+    static const weightedPosition zero;
+};
+
+
+/*---------------------------------------------------------------------------*\
+                      Class weightedPosition Declaration
+\*---------------------------------------------------------------------------*/
+
+class weightedPosition
+:
+    public Tuple2<scalar, point>
+{
+public:
+
+    // Constructors
+
+        //- Construct null
+        weightedPosition();
+
+        //- Construct from components
+        weightedPosition(const scalar s, const point& p);
+
+
+    // Member Functions
+
+        // Helpers
+
+            //- Get points
+            static void getPoints
+            (
+                const UList<weightedPosition>& in,
+                List<point>& out
+            );
+
+            //- Set points
+            static void setPoints
+            (
+                const UList<point>& in,
+                List<weightedPosition>& out
+            );
+
+
+        //- Summation operator
+        static void plusEqOp(weightedPosition& x, const weightedPosition& y);
+
+
+        // Transformation operators
+
+            void operator()
+            (
+                const vectorTensorTransform& vt,
+                const bool forward,
+                List<weightedPosition>& fld
+            ) const;
+
+            void operator()
+            (
+                const vectorTensorTransform& vt,
+                const bool forward,
+                List<List<weightedPosition>>& flds
+            ) const;
+
+            void operator()
+            (
+                const coupledPolyPatch& cpp,
+                Field<weightedPosition>& fld
+            ) const;
+
+            template<template<class> class Container>
+            void operator()
+            (
+                const coupledPolyPatch& cpp,
+                Container<weightedPosition>& map
+            ) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "weightedPositionTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/mesh/snappyHexMesh/meshRefinement/weightedPositionTemplates.C

@@ -0,0 +1,61 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2020 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+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 "vectorTensorTransform.H"
+#include "coupledPolyPatch.H"
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+template<template<class> class Container>
+void Foam::weightedPosition::operator()
+(
+    const coupledPolyPatch& cpp,
+    Container<weightedPosition>& map
+)
+const
+{
+    Field<point> fld(map.size());
+    label i = 0;
+    forAllConstIters(map, iter)
+    {
+        point pt(iter->second());
+        if (mag(iter->first()) > VSMALL)
+        {
+            pt /= iter->first();
+        }
+        fld[i++] = pt;
+    }
+    cpp.transformPosition(fld);
+    i = 0;
+    forAllIters(map, iter)
+    {
+        iter->second() = fld[i++]*iter->first();
+    }
+}
+
+
+// ************************************************************************* //

src/mesh/snappyHexMesh/snappyHexMeshDriver/snappySnapDriver.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
-    Copyright (C) 2015-2019 OpenCFD Ltd.
+    Copyright (C) 2015-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -48,6 +48,7 @@ Description
 #include "localPointRegion.H"
 #include "PatchTools.H"
 #include "refinementFeatures.H"
+#include "weightedPosition.H"
 #include "profiling.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
@@ -234,8 +235,11 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothInternalDisplacement
 
 
     // Calculate average of connected cells
-    labelList nCells(mesh.nPoints(), Zero);
+    Field<weightedPosition> sumLocation
-    pointField sumLocation(mesh.nPoints(), Zero);
+    (
+        mesh.nPoints(),
+        pTraits<weightedPosition>::zero
+    );
 
     forAll(isMovingPoint, pointi)
     {
@@ -243,22 +247,22 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothInternalDisplacement
         {
             const labelList& pCells = mesh.pointCells(pointi);
 
-            forAll(pCells, i)
+            sumLocation[pointi].first() = pCells.size();
+            for (const label celli : pCells)
             {
-                sumLocation[pointi] += mesh.cellCentres()[pCells[i]];
+                sumLocation[pointi].second() += mesh.cellCentres()[celli];
-                nCells[pointi]++;
             }
         }
     }
 
     // Sum
-    syncTools::syncPointList(mesh, nCells, plusEqOp<label>(), label(0));
     syncTools::syncPointList
     (
         mesh,
         sumLocation,
-        plusEqOp<point>(),
+        weightedPosition::plusEqOp,     // combine op
-        vector::zero
+        pTraits<weightedPosition>::zero,// null value (not used)
+        pTraits<weightedPosition>::zero // transform class
     );
 
     tmp<pointField> tdisplacement(new pointField(mesh.nPoints(), Zero));
@@ -268,10 +272,12 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothInternalDisplacement
 
     forAll(displacement, pointi)
     {
-        if (nCells[pointi] > 0)
+        const weightedPosition& wp = sumLocation[pointi];
+        if (mag(wp.first()) > VSMALL)
         {
             displacement[pointi] =
-                sumLocation[pointi]/nCells[pointi]-mesh.points()[pointi];
+                wp.second()/wp.first()
+              - mesh.points()[pointi];
             nAdapted++;
         }
     }
@@ -355,9 +361,12 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
     // Get average position of boundary face centres
     // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-    vectorField avgBoundary(pointFaces.size(), Zero);
+    Field<weightedPosition> avgBoundary
-    labelList nBoundary(pointFaces.size(), Zero);
+    (
-
+        pointFaces.size(),
+        pTraits<weightedPosition>::zero
+    );
+    {
         forAll(pointFaces, patchPointi)
         {
             const labelList& pFaces = pointFaces[patchPointi];
@@ -368,8 +377,9 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
 
                 if (isMasterFace.test(pp.addressing()[facei]))
                 {
-                avgBoundary[patchPointi] += pp[facei].centre(points);
+                    avgBoundary[patchPointi].first() += 1.0;
-                nBoundary[patchPointi]++;
+                    avgBoundary[patchPointi].second() +=
+                        pp[facei].centre(points);
                 }
             }
         }
@@ -379,32 +389,33 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
             mesh,
             pp.meshPoints(),
             avgBoundary,
-        plusEqOp<point>(),  // combine op
+            weightedPosition::plusEqOp,     // combine op
-        vector::zero        // null value
+            pTraits<weightedPosition>::zero,// null value (not used)
-    );
+            pTraits<weightedPosition>::zero // transform class
-    syncTools::syncPointList
-    (
-        mesh,
-        pp.meshPoints(),
-        nBoundary,
-        plusEqOp<label>(),  // combine op
-        label(0)            // null value
         );
 
+        // Normalise
         forAll(avgBoundary, i)
         {
-        avgBoundary[i] /= nBoundary[i];
+            // Note: what if there is no master boundary face?
+            if (mag(avgBoundary[i].first()) > VSMALL)
+            {
+                avgBoundary[i].second() /= avgBoundary[i].first();
+            }
+        }
     }
 
 
     // Get average position of internal face centres
     // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-    vectorField avgInternal;
+    Field<weightedPosition> avgInternal;
-    labelList nInternal;
     {
-        vectorField globalSum(mesh.nPoints(), Zero);
+        Field<weightedPosition> globalSum
-        labelList globalNum(mesh.nPoints(), Zero);
+        (
+            mesh.nPoints(),
+            pTraits<weightedPosition>::zero
+        );
 
         // Note: no use of pointFaces
         const faceList& faces = mesh.faces();
@@ -416,8 +427,9 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
 
             forAll(f, fp)
             {
-                globalSum[f[fp]] += fc;
+                weightedPosition& wp = globalSum[f[fp]];
-                globalNum[f[fp]]++;
+                wp.first() += 1.0;
+                wp.second() += fc;
             }
         }
 
@@ -444,8 +456,9 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
 
                     forAll(f, fp)
                     {
-                        globalSum[f[fp]] += fc;
+                        weightedPosition& wp = globalSum[f[fp]];
-                        globalNum[f[fp]]++;
+                        wp.first() += 1.0;
+                        wp.second() += fc;
                     }
                 }
             }
@@ -455,35 +468,28 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
         (
             mesh,
             globalSum,
-            plusEqOp<vector>(), // combine op
+            weightedPosition::plusEqOp,     // combine op
-            vector::zero        // null value
+            pTraits<weightedPosition>::zero,// null value (not used)
-        );
+            pTraits<weightedPosition>::zero // transform class
-        syncTools::syncPointList
-        (
-            mesh,
-            globalNum,
-            plusEqOp<label>(),  // combine op
-            label(0)            // null value
         );
 
+
         avgInternal.setSize(meshPoints.size());
-        nInternal.setSize(meshPoints.size());
 
         forAll(avgInternal, patchPointi)
         {
             label meshPointi = meshPoints[patchPointi];
+            const weightedPosition& wp = globalSum[meshPointi];
 
-            nInternal[patchPointi] = globalNum[meshPointi];
+            avgInternal[patchPointi].first() = wp.first();
-
+            if (mag(wp.first()) < VSMALL)
-            if (nInternal[patchPointi] == 0)
             {
-                avgInternal[patchPointi] = globalSum[meshPointi];
+                // Set to zero?
+                avgInternal[patchPointi].second() = wp.second();
             }
             else
             {
-                avgInternal[patchPointi] =
+                avgInternal[patchPointi].second() = wp.second()/wp.first();
-                    globalSum[meshPointi]
-                  / nInternal[patchPointi];
             }
         }
     }
@@ -514,13 +520,15 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
         label meshPointi = meshPoints[i];
         const point& currentPos = pp.points()[meshPointi];
 
-        // Now we have the two average points: avgBoundary and avgInternal
+        // Now we have the two average points and their counts:
-        // and how many boundary/internal faces connect to the point
+        //  avgBoundary and avgInternal
-        // (nBoundary, nInternal)
         // Do some blending between the two.
         // Note: the following section has some reasoning behind it but the
         // blending factors can be experimented with.
 
+        const weightedPosition& internal = avgInternal[i];
+        const weightedPosition& boundary = avgBoundary[i];
+
         point newPos;
 
         if (!nonManifoldPoint.test(i))
@@ -532,14 +540,17 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
 
             point avgPos =
                 (
-                   internalBlend*nInternal[i]*avgInternal[i]
+                   internalBlend*internal.first()*internal.second()
-                  +(1-internalBlend)*nBoundary[i]*avgBoundary[i]
+                  +(1-internalBlend)*boundary.first()*boundary.second()
                 )
-              / (internalBlend*nInternal[i]+(1-internalBlend)*nBoundary[i]);
+              / (
+                    internalBlend*internal.first()
+                   +(1-internalBlend)*boundary.first()
+                );
 
             newPos = (1-blend)*avgPos + blend*currentPos;
         }
-        else if (nInternal[i] == 0)
+        else if (internal.first() == 0)
         {
             // Non-manifold without internal faces. Use any connected cell
             // as internal point instead. Use precalculated any cell to avoid
@@ -550,7 +561,7 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
             scalar cellCBlend = 0.8;
             scalar blend = 0.1;
 
-            point avgPos = (1-cellCBlend)*avgBoundary[i] + cellCBlend*cc;
+            point avgPos = (1-cellCBlend)*boundary.second() + cellCBlend*cc;
 
             newPos = (1-blend)*avgPos + blend*currentPos;
         }
@@ -561,8 +572,8 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::smoothPatchDisplacement
             scalar blend = 0.1;
 
             point avgPos =
-                internalBlend*avgInternal[i]
+                internalBlend*internal.second()
-              + (1-internalBlend)*avgBoundary[i];
+              + (1-internalBlend)*boundary.second();
 
             newPos = (1-blend)*avgPos + blend*currentPos;
         }
@@ -980,26 +991,22 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::avgCellCentres
 {
     const labelListList& pointFaces = pp.pointFaces();
 
-
+    Field<weightedPosition> avgBoundary
-    tmp<pointField> tavgBoundary
     (
-        new pointField(pointFaces.size(), Zero)
+        pointFaces.size(),
+        pTraits<weightedPosition>::zero
     );
-    pointField& avgBoundary = tavgBoundary.ref();
-    labelList nBoundary(pointFaces.size(), Zero);
 
     forAll(pointFaces, pointi)
     {
         const labelList& pFaces = pointFaces[pointi];
 
+        avgBoundary[pointi].first() = pFaces.size();
         forAll(pFaces, pfi)
         {
             label facei = pFaces[pfi];
-            label meshFacei = pp.addressing()[facei];
+            label own = mesh.faceOwner()[pp.addressing()[facei]];
-
+            avgBoundary[pointi].second() += mesh.cellCentres()[own];
-            label own = mesh.faceOwner()[meshFacei];
-            avgBoundary[pointi] += mesh.cellCentres()[own];
-            nBoundary[pointi]++;
         }
     }
 
@@ -1008,22 +1015,14 @@ Foam::tmp<Foam::pointField> Foam::snappySnapDriver::avgCellCentres
         mesh,
         pp.meshPoints(),
         avgBoundary,
-        plusEqOp<point>(),  // combine op
+        weightedPosition::plusEqOp,     // combine op
-        vector::zero        // null value
+        pTraits<weightedPosition>::zero,// null value (not used)
-    );
+        pTraits<weightedPosition>::zero // transform class
-    syncTools::syncPointList
-    (
-        mesh,
-        pp.meshPoints(),
-        nBoundary,
-        plusEqOp<label>(),  // combine op
-        label(0)            // null value
     );
 
-    forAll(avgBoundary, i)
+    tmp<pointField> tavgBoundary(new pointField(avgBoundary.size()));
-    {
+    weightedPosition::getPoints(avgBoundary, tavgBoundary.ref());
-        avgBoundary[i] /= nBoundary[i];
+
-    }
     return tavgBoundary;
 }
 

src/mesh/snappyHexMesh/snappyHexMeshDriver/snappySnapDriverFeature.C

@@ -676,6 +676,21 @@ void Foam::snappySnapDriver::calcNearestFacePointProperties
         List<point>(),
         mapDistribute::transform()
     );
+
+    {
+        // Make into displacement before synchronising to avoid any problems
+        // with parallel cyclics
+        pointField localPoints(pp.points(), pp.meshPoints());
+        forAll(pointFaceCentres, pointi)
+        {
+            const point& pt = pp.points()[pp.meshPoints()[pointi]];
+
+            List<point>& pFc = pointFaceCentres[pointi];
+            for (point& p : pFc)
+            {
+                p -= pt;
+            }
+        }
         syncTools::syncPointList
         (
             mesh,
@@ -683,8 +698,20 @@ void Foam::snappySnapDriver::calcNearestFacePointProperties
             pointFaceCentres,
             listPlusEqOp<point>(),
             List<point>(),
-        mapDistribute::transformPosition()
+            mapDistribute::transform()
         );
+        forAll(pointFaceCentres, pointi)
+        {
+            const point& pt = pp.points()[pp.meshPoints()[pointi]];
+
+            List<point>& pFc = pointFaceCentres[pointi];
+            for (point& p : pFc)
+            {
+                p += pt;
+            }
+        }
+    }
+
     syncTools::syncPointList
     (
         mesh,