[Pyrokrates]

Hey,


I would like to do some simulations of pleated filter with porous media. Therefor I started with an easy example using a flat filter with an inlet zone pre and outlet zone after my filter. When I simulate with "simpleFoam", I get the correct pressure drop of 759.5 Pa (compared to Darcy theoretical value with 759.8 Pa). When I do the exactly same simulation with "porousSimpleFoam" I get a pressure drop of 1519.0 Pa which is exactly the double value of real pressure. Can anybody help with this?


The second thing I'm interested in is the pressure drop and velocity close the the filter inlet and outlet. Depending on my fvSolution settings it varies strong. For future calculations I need a stable velocity at the inlet and outlet of the filter instead of fluctuations and jumps of velocity. Another problem of the velocity jumps is, that the pressure can reach negative values. These are close to zero but stil negative which is a problem for following studies.
Do you have any tips about which solver to use best? I tried out



p
{
solver PCG;
preconditioner DIC;
tolerance 1e-16;
relTol 5e-2;
}
"(U|k|omega)"
{
solver PBiCGStab;
preconditioner DILU;
tolerance 1e-16;
relTol 1e-3;
}


which seems to produce the best results. I'm also using a variation of relaxation parameter for U, which I decrease from time to time. This also corrects my pressure drop and velocity a litte bit.





Thx in advance


Pyrokrates