ENH: Correct SuSp dimensions and adding function to mapping util

src/finiteArea/finiteArea/fam/famSup.C

@@ -165,9 +165,19 @@ SuSp
     );
     faMatrix<Type>& fam = tfam.ref();
 
-    fam.diag() += mesh.S()*max(sp.internalField(), scalar(0));
+   fam.diag() +=
+        mesh.S()*max
+        (
+            sp.internalField(),
+            dimensionedScalar("0", sp.dimensions(), Zero)
+        );
 
-    fam.source() -= mesh.S()*min(sp.internalField(), scalar(0))
+    fam.source() -=
+        mesh.S()*min
+        (
+            sp.internalField(),
+            dimensionedScalar("0", sp.dimensions(), Zero)
+        )
         *vf.internalField();
 
     return tfam;

src/finiteArea/interpolation/volSurfaceMapping/volSurfaceMapping.C

@@ -67,6 +67,44 @@ Foam::tmp<Foam::Field<Type>> Foam::volSurfaceMapping::mapToSurface
 }
 
 
+template<class Type>
+Foam::tmp<Foam::Field<Type>> Foam::volSurfaceMapping::mapInternalToSurface
+(
+    const typename GeometricField<Type, fvPatchField, volMesh>::Boundary& df
+) const
+{
+    // Grab labels for all faces in faMesh
+    const labelList& faceLabels = mesh_.faceLabels();
+
+    tmp<Field<Type>> tresult
+    (
+        new Field<Type>(faceLabels.size(), Zero)
+    );
+    Field<Type>& result = tresult.ref();
+
+    // Get reference to volume mesh
+    const polyMesh& pMesh = mesh_();
+    const polyBoundaryMesh& bm = pMesh.boundaryMesh();
+
+    label patchID, faceID;
+
+    // Grab droplet cloud source by identifying patch and face
+    forAll(faceLabels, i)
+    {
+        // Escape if face is beyond active faces, eg belongs to a face zone
+        if (faceLabels[i] < pMesh.nFaces())
+        {
+            patchID = bm.whichPatch(faceLabels[i]);
+            faceID = bm[patchID].whichFace(faceLabels[i]);
+
+            result[i] = df[patchID].patchInternalField()()[faceID];
+        }
+    }
+
+    return tresult;
+}
+
+
 template<class Type>
 void Foam::volSurfaceMapping::mapToVolume
 (

src/finiteArea/interpolation/volSurfaceMapping/volSurfaceMapping.H

@@ -96,6 +96,15 @@ public:
             GeometricField<Type, fvPatchField, volMesh>::Boundary& df
         ) const;
 
+
+        //- Map patch internal field to surface
+        template<class Type>
+        tmp<Field<Type>> mapInternalToSurface
+        (
+            const typename
+            GeometricField<Type, fvPatchField, volMesh>::Boundary& df
+        ) const;
+
         //- Map surface field to volume boundary field
         template<class Type>
         void mapToVolume