CFD Online Discussion Forums - Porosity treatment in OpenFOAM

Hey,

I'm creating a solver for fibrous porous media and therefore have to deal with anistropic permability.

I have a question regarding the explicit/implicit treatment of the porosity. I an old thread, olsen posted:

Quote:

Much more importantly - you'll need the implicit porosity solver if the resistances are large, heavily anisotropic or not aligned with the global coordinates.

My solver is based on porousInterFoam (OF2.1.1) which uses the PIMPLE algorithm. There is no entry in "createFields" which detects if the porosity should be solved implicit or explicit. This seems to be an option which is only implemented in solvers with SIMPLE. Is that true? Is olsen's statement only be true for SIMPLE?

And furthermore, why is the ddt-term "pZones.ddt(rho, U)" in the UEqn of porousInterFoam commented out? This prevents the solver from taking the porosity in account for the calculation. Why would that make sense? I ran the simulation with the pZones.ddt term and porosity of 0.45. There was no difference in flow propagation/speed at all. This is really confusing me! Any hinds?

Thanks in advance,
Alex