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Hi,


Recently, I noticed that having high aspect ratio cells away from the wall leads to a very low determinant for those cells. It has absolutely no effect on flow field (UEqn) but when I add a passive scalar transport equation to the simulation, the presence of these underdetermined cells leads to the blow-up of the scalar equation (only) with the momentum equation still converging.

To circumvent this issue, I alter my mesh such that I get rid of these underdetermined cells away from the wall. That helps and doesn't cause scalar field to blow up.

Has anybody noticed this kind of behavior before?
If yes, is there anything we could do than to alter the mesh?
I have tried all kinds of bounded schemes. They don't help.

PS:To get the idea of what I am talking about look at my old thread:
TEqn (passive scalar) diverges all of a sudden