Hi Rob! Indeed polyhedral mesh seems to provide more stable simulations. Thanks for this recommendation. I also decreased the growth rate which solved the problem that I described above. However, now I see that there is another issue with no difference in a gas fraction before and after the porous media model. As porous zone causes resistance I expect to see such a difference. The model converges nicely now and I don't see any discrepancies that would cause such inaccuracy in results.

Do you have any advice regarding this one? Thanks a lot for helping!