[KTG]

Hi Foamers,


I am working on a benchmark case of a porous cube in a wind tunnel. I am considering the flow incompressible. I have tried to use pimple foam with a very standard porous zone added through fvOptions.



Two issues have come up that seem to be really destroying my results:


1) There doesn't seem to be anywhere to specify porosity! It seems like to include porosity a new solver would need to be written since porosity would multiply various terms in the NSE that I don't think can be modified by fvOptions. If this is the case, why do we have porous zones in fvOptions - is there a physically defensible situation where you would have momentum extraction due to porous media without porosity effects? In my case, about 50 percent of the flow needs to be diverted around the cube regardless of the darcy-forchheimer coefficients. I looked at porousSimpleFoam, and it seems to have the same problem. Am I missing something here? I think the equations I should be solving should be somthing like equations (1) and (2) in this paper: https://static1.squarespace.com/stat...01452-main.pdf



2) There doesn't seem to be a place to specify density - the flow may be incompressible, but doesn't the affect the total momentum extraction? I measured the pressure drop in paraview to do a dummy check, and concluded that openFoam was operating with rho=1.


Here is an example of the porous zones I have tried:

porosity1
{
    type            explicitPorositySource;
    active          true;

    explicitPorositySourceCoeffs
    {
        type            DarcyForchheimer;
        selectionMode   cellZone;
        cellZone        cube_C1;

        DarcyForchheimerCoeffs
        {
            d   d [0 -2 0 0 0 0 0] (0 0 0);
            f   f [0 -1 0 0 0 0 0] (.151565 .151565 .151565);

            coordinateSystem
            {
                origin  (0 0 0);
                e1      (1 0 0);
                e2      (0 1 0);
            }
        }
    }
}

https://www.openfoam.com/documentati...r.html#details



I am entertaining any suggestions - the results I am getting are off by an order of magnitude, so.... please help me.


Thanks