[sle]

Does anybody else have difficulty obtaining convergence in porous media domains for homogeneous multi-component gaseous species?

I am modeling the mixing of two air pollutants at very low concentrations (ppm) inside a large reactor. I have a thin (6") porous media that spans a very large duct cross-section. The porous media is specified with a quadratic pressure drop coefficient.

No matter what I do with the mesh, I always seem to have high residuals on the mass fraction for one of the pollutants. Investigating the high residuals indicates what appears to be a point discontinuity of sorts (sudden area of high concentration).

Has anybody else encountered and solved this problem? Also, yes, I am using double precision.