Learning Forum

[schwaral]

I wonder if this is one way to create the porous jump or should I do it in a different way?

1. Splitted Geometry
2. Mesh the geometry with one interface
3. In fluent: interface --> (static, matched) --> change interior to porous jump condition. Here I wonder should I change all 4 or just one interior to porous jump?

[Ulrich]

I strongly recommend to use a conformal mesh where you want to assign a porous jump. I have never tested or seen a porous jump at a grid interface.nWith a conformal mesh the setup is straightforward, changing the right interior to type porous-jump, and you can visually check whether you have the right zone.n

[schwaral]

I did it like you recommended (picture here of my simple 3D case). However I face the problem, when I set for the porous jump conditions a thickness of 1mm the calculation diverges. When I use a thickness of 0,01mm the solution converges. C2 is in my case 0. Face permeability (= permeability I used in standard porous zone in my other setup) = 1e-11. Do you have any idea why the solver has a problem with the thickness lager then 0,01mm? my case is super simple here and for more complex 3D case I face the same problem. I dont think it is related to the mesh. nFor my 3D case I also receive these two errors when usin 1mm thickness (maybe they help). I could not really find something online that was helpfull.detecting divergent flow at 1D porous jump zone 3nReverse porous jump zone 3 orientation based on bulk flow directionnbest regards, Alexn

[Rob]

1e-11 is a very small coefficient, but otherwise I can't see why it's not working. How does the flow look before it fails?n

[schwaral]

Okay I think I forgot to devide by the face thickness to convert the permeability from porous media to porous jump. So now my face permeability is a little bit reduced. Just to make sure, cell size at porous jump does not affect the stability in diffrent ways cell size usually affect the stability?n

[Rob]

Shouldn't have any more effect than usual assuming you're picking up the gradients etc that may or may not be associated with the pressure drop.