functionObjects::wallShearStress: Added phase support

wallShearStress can now be used to calculate the phase wall shear-stress in
multiphase systems, e.g.

    multiphaseEulerFoam -postProcess -func 'wallShearStress(phase=water)' -latestTime

src/functionObjects/field/wallShearStress/wallShearStress.C

@@ -102,9 +102,11 @@ Foam::functionObjects::wallShearStress::wallShearStress
     fvMeshFunctionObject(name, runTime, dict),
     logFiles(obr_, name),
     writeLocalObjects(obr_, log),
+    phaseName_(word::null),
     patchSet_()
 {
     read(dict);
+    resetLocalObjectName(IOobject::groupName(type(), phaseName_));
 }
 
 
@@ -121,6 +123,8 @@ bool Foam::functionObjects::wallShearStress::read(const dictionary& dict)
     fvMeshFunctionObject::read(dict);
     writeLocalObjects::read(dict);
 
+    phaseName_ = dict.lookupOrDefault<word>("phase", word::null);
+
     const polyBoundaryMesh& pbm = mesh_.boundaryMesh();
 
     patchSet_ =
@@ -177,34 +181,38 @@ bool Foam::functionObjects::wallShearStress::read(const dictionary& dict)
 
 bool Foam::functionObjects::wallShearStress::execute()
 {
+    const word fieldName(IOobject::groupName(type(), phaseName_));
+
     typedef compressible::momentumTransportModel cmpModel;
     typedef incompressible::momentumTransportModel icoModel;
 
-    tmp<volSymmTensorField> tau;
-    if (mesh_.foundObject<cmpModel>(momentumTransportModel::typeName))
+    const word momentumTransportModelName
+    (
+        IOobject::groupName(momentumTransportModel::typeName, phaseName_)
+    );
+
+    if (mesh_.foundObject<cmpModel>(momentumTransportModelName))
     {
         const cmpModel& model =
-            mesh_.lookupObject<cmpModel>(momentumTransportModel::typeName);
+            mesh_.lookupObject<cmpModel>(momentumTransportModelName);
 
-        tau = model.devTau();
+        return store(fieldName, calcShearStress(model.devTau()));
     }
-    else if (mesh_.foundObject<icoModel>(momentumTransportModel::typeName))
+    else if (mesh_.foundObject<icoModel>(momentumTransportModelName))
     {
         const icoModel& model =
-            mesh_.lookupObject<icoModel>(momentumTransportModel::typeName);
+            mesh_.lookupObject<icoModel>(momentumTransportModelName);
 
-        tau = model.devSigma();
+        return store(fieldName, calcShearStress(model.devSigma()));
     }
     else
     {
         FatalErrorInFunction
             << "Unable to find turbulence model in the "
             << "database" << exit(FatalError);
+
+        return false;
     }
-
-    word name(type());
-
-    return store(name, calcShearStress(tau));
 }
 
 
@@ -216,8 +224,10 @@ bool Foam::functionObjects::wallShearStress::write()
 
     logFiles::write();
 
-    const volVectorField& wallShearStress =
-        obr_.lookupObject<volVectorField>(type());
+    const volVectorField& wallShearStress = obr_.lookupObject<volVectorField>
+    (
+        IOobject::groupName(type(), phaseName_)
+    );
 
     const fvPatchList& patches = mesh_.boundary();
 

src/functionObjects/field/wallShearStress/wallShearStress.H

@@ -26,7 +26,7 @@ Class
 
 Description
     Calculates and write the shear-stress at wall patches as
-    the volVectorField field 'wallShearStress'.
+    the volVectorField field 'wallShearStress' or 'wallShearStress.<phase>'.
 
         \f[
             Stress = R \dot n
@@ -55,9 +55,10 @@ Description
 
 Usage
     \table
-        Property | Description               | Required    | Default value
+        Property | Description                | Required   | Default value
         type     | type name: wallShearStress | yes        |
         patches  | list of patches to process | no         | all wall patches
+        phase    | phase name                 | no         |
     \endtable
 
 Note
@@ -102,16 +103,16 @@ class wallShearStress
     public logFiles,
     public writeLocalObjects
 {
+    // Private Data
 
-protected:
-
-    // Protected data
+        //- The name of the phase
+        word phaseName_;
 
         //- Optional list of patches to process
         labelHashSet patchSet_;
 
 
-    // Protected Member Functions
+    // Private Member Functions
 
         //- File header information
         virtual void writeFileHeader(const label i);

src/functionObjects/field/yPlus/yPlus.H

@@ -26,7 +26,7 @@ Class
 
 Description
     Evaluates and outputs turbulence y+ for models. Values written to
-    time directories as field 'yPlus' or 'yPlus.phase'.
+    time directories as field 'yPlus' or 'yPlus.<phase>'.
 
     Example of function object specification:
     \verbatim
@@ -90,16 +90,12 @@ class yPlus
     public logFiles,
     public writeLocalObjects
 {
-protected:
-
-    // Protected data
+    // Private data
 
         //- Optional phase name
         word phaseName_;
 
 
-private:
-
     // Private Member Functions
 
         //- File header information