[mcailloux]

Dear OpenFOAM users,

I am trying to implement diffusion between two phases in the already existed compressibleMultiphaseInterFoam. To do that, I have taken some parts of the interMixing solver and add it to the compressibleMultiphaseInterFoam solver.

It leads to solve the alpha for the two miscibles phases like that :

fvScalarMatrix alphaEqn
(
fvm::ddt(alpha)
+ fvc::div(phiAlpha)
- fvm::laplacian(Dc23 + Dc32, alpha)
- Su
- alpha*Sp
);
alphaEqn.solve();

Adding diffusion leads me to add the laplacian operator in the equation from the basic compressibleMultiphaseInterFoam solver.

And my problem is that the laplacian term gives me some strange behaviour since I have a normal evolution of the volume fractions in my run case in 2D (only 1 cell is the z direction) but in a 3D case, the volume fraction doesn't move any more and stays the same as in the initial time.

Moreover, when I comment the line containing the laplacian, my solver gives me logical results even in 3D. So that I conclude that my problem for the run in 3 dimensions is directly linked to the addition of the laplacian operator but I don't have any idea to understand why...

Many thanks for your help.

Mathieu