Change the strain rate from mag(grad(U)) to mag(symm(grad(U))). The

old formulation includes the effect of gradients caused by solid body
rotation on the strain rate, while the second returns only the
irrotational part.

src/transportModels/incompressible/viscosityModels/viscosityModel/viscosityModel.C

@@ -26,22 +26,20 @@ License
 
 #include "viscosityModel.H"
 #include "volFields.H"
-#include "fvc.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
+#include "fvcGrad.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
-defineTypeNameAndDebug(viscosityModel, 0);
-defineRunTimeSelectionTable(viscosityModel, dictionary);
+namespace Foam
+{
+    defineTypeNameAndDebug(viscosityModel, 0);
+    defineRunTimeSelectionTable(viscosityModel, dictionary);
+}
 
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-viscosityModel::viscosityModel
+Foam::viscosityModel::viscosityModel
 (
     const word& name,
     const dictionary& viscosityProperties,
@@ -58,13 +56,13 @@ viscosityModel::viscosityModel
 
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
-tmp<volScalarField> viscosityModel::strainRate() const
+Foam::tmp<Foam::volScalarField> Foam::viscosityModel::strainRate() const
 {
-    return mag(fvc::grad(U_));
+    return mag(symm(fvc::grad(U_)));
 }
 
 
-bool viscosityModel::read(const dictionary& viscosityProperties)
+bool Foam::viscosityModel::read(const dictionary& viscosityProperties)
 {
     viscosityProperties_ = viscosityProperties;
 
@@ -72,8 +70,4 @@ bool viscosityModel::read(const dictionary& viscosityProperties)
 }
 
 
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
 // ************************************************************************* //