Hello,

I am trying to run a case where all sides have periodic boundary conditions and flow is driven by a momentum source. This is modeling a unit cell of some porous media. Very low Reynolds number, laminar, incompressible, steady-state. I’m having some difficulty with running cases with more complicated geometries, I’m guessing due to mesh issues. I started with a simple case of some connected rectangular channels, in the image below. Opposing faces of the channels have periodic boundary conditions, so there’s 3 pairs of periodic BCs. I ran the case with a momentum source in 1 direction, and got reasonable results, the velocity magnitude field is below.

When I continue on with a slightly more complicated geometry, the case still runs and things check out.

Now when I go to a more complicated geometry, the case fails. These geometries still have matching faces on opposing sides of the CAD file, but it seems that mesh cells don’t line up as well on corresponding faces. I had hoped the cyclic AMI boundary condition would take care of this. I tried hex and tet meshes with different degrees of fineness. The cases do not run at all, they say “case was prepared successfully”, then it fails, and there is no error log. Would appreciate any recommendations or advice for how to proceed with meshing or troubleshooting this issue. Thanks!