functionObjects: phaseScalarTransport: Made writing of alpha*s switchable

src/functionObjects/solvers/phaseScalarTransport/phaseScalarTransport.C

@@ -313,21 +313,7 @@ Foam::functionObjects::phaseScalarTransport::phaseScalarTransport
         ),
         mesh_
     ),
-    alphaS_
-    (
-        IOobject
-        (
-            "alpha"
-          + word(toupper(fieldName_[0]))
-          + fieldName_(1, fieldName_.size() - 1),
-            mesh_.time().timeName(),
-            mesh_,
-            IOobject::NO_READ,
-            IOobject::AUTO_WRITE
-        ),
-        mesh_,
-        dimensionedScalar(s_.dimensions(), Zero)
-    ),
+    alphaSPtr_(nullptr),
     PhiPtr_(nullptr)
 {
     if (phaseName_ == word::null)
@@ -383,6 +369,7 @@ bool Foam::functionObjects::phaseScalarTransport::read(const dictionary& dict)
 
     dict.readIfPresent("nCorr", nCorr_);
     dict.readIfPresent("residualAlpha", residualAlpha_);
+    writeAlphaField_ = dict.lookupOrDefault<bool>("writeAlphaField", true);
 
     if (dict.found("fvOptions"))
     {
@@ -479,7 +466,39 @@ bool Foam::functionObjects::phaseScalarTransport::execute()
     }
 
     // Update
-    alphaS_ = alpha*s_;
+    if (writeAlphaField_)
+    {
+        if (!alphaSPtr_.valid())
+        {
+            alphaSPtr_.set
+            (
+                new volScalarField
+                (
+                    IOobject
+                    (
+                        "alpha"
+                      + word(toupper(fieldName_[0]))
+                      + fieldName_(1, fieldName_.size() - 1),
+                        mesh_.time().timeName(),
+                        mesh_,
+                        IOobject::NO_READ,
+                        IOobject::AUTO_WRITE
+                    ),
+                    mesh_,
+                    dimensionedScalar(s_.dimensions(), Zero)
+                )
+            );
+        }
+
+        alphaSPtr_() = alpha*s_;
+    }
+    else
+    {
+        if (alphaSPtr_.valid())
+        {
+            alphaSPtr_().clear();
+        }
+    }
 
     Info<< endl;
 

src/functionObjects/solvers/phaseScalarTransport/phaseScalarTransport.H

@@ -48,14 +48,16 @@ Description
 
 Usage
     \table
-        Property      | Description                       | Req'd? | Default
-        alpha         | Name of the volume-fraction field | no \\
-                      | alpha.<phase-name>
-        alphaPhi      | Name of the phase-flux field      | no \\
-                      | alphaPhi.<phase-name>
-        p             | Name of the pressure field        | no     | p
-        residualAlpha | Small volume fraction used to stabilise the solution \\
-                      | no | rootSmall
+        Property        | Description                        | Req'd? | Default
+        alpha           | Name of the volume-fraction field  | no\\
+                        | alpha.<phase-name>
+        alphaPhi        | Name of the phase-flux field       | no\\
+                        | alphaPhi.<phase-name>
+        p               | Name of the pressure field         | no     | p
+        residualAlpha   | Small volume fraction used to stabilise the solution\\
+                        | no | rootSmall
+        writeAlphaField | Also write out alpha multiplied by the field\\
+                        | no | true
     \endtable
 
     Example specification for interFoam:
@@ -158,6 +160,10 @@ class phaseScalarTransport
         //- Name of field whose schemes are used (optional)
         word schemesField_;
 
+        //- Flag to indicate whether to write the field multiplied by the phase
+        //  fraction
+        bool writeAlphaField_;
+
         //- Run-time selectable finite volume options, e.g. sources, constraints
         fv::optionList fvOptions_;
 
@@ -165,7 +171,7 @@ class phaseScalarTransport
         volScalarField s_;
 
         //- The field multiplied by the phase fraction
-        volScalarField alphaS_;
+        autoPtr<volScalarField> alphaSPtr_;
 
         //- Potential field used to generate the phase flux
         autoPtr<volScalarField> PhiPtr_;