CFD Online Discussion Forums - How to calculate the flux of this term grad(alpha1)*alphaf*U?

Hi Foamers,

I am working on a modified solver based on interFoam, having problem to calculate the flux of the following term (in modified VOF method):

https://66.media.tumblr.com/09e03f7c...ssaho1_250.png

where alpha1 is the liquid phase volume fraction, alphaf the fluid volume fraction, and U the fluid velocity. The term alphaf is introduced because there is a third phase: solid.

To calculate the flux of this term, I tried the following code:

Code:

volVectorField afGrada1("afGrada1", alphaf*fvc::grad(alpha1));

//volVectorField afGrada1("afGrada1", alphaf*fvc::snGrad(alpha1));

surfaceScalarField afGrada1Uf(fvc::interpolate(U*afGrada1) & mesh.Sf());

But it seems that there is a problem on the gradient of alpha1.

Code:

alphaEqn.H: In function ‘int main(int, char**)’:

alphaEqn.H:16:69: error: no matching function for call to ‘Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>::GeometricField(const char [9], Foam::tmp<Foam::Field<double> >)’

 volVectorField afGrada1("afGrada1", alphaf*fvc::grad(alpha1));

                                                             ^

alphaEqn.H:16:69: note: candidates are: ...........

I have tried a lot of combinations, but none is working. Any idea to calculate the flux of alphaf*grad(alpha1)*U?

Thanks in advance.

David