Reply To: non-physical negative uds concentrations with small diffusion coefficient

[grayg34]

I have added a screenshot of the mesh for reference. The surface mesh is reasonably coarse, 1 full cell and 2 half cells along that corner piece. Internally there are very fine prism layers with first cell thickness of ~1e-6m.

 

I have no doubt the mesh is a large part of the issue with the non-physical concentrations, but as I said before I am kind of stuck with the current mesh and would like to try and make it workable. So far modifying the diffusion coefficient has kept the negative concentration from running away and causing major problems.