Strange residuals of the Density Based Solver
 

Hello community,

I have trouble in the interpretation of the residuals of the Density Based Solver. I started the first simulation with a coarse grid and - after the continuity stopped to converge at ~4e-3 - I interpolated the solution on a finer grid and started the simulation again. At the start I realized that I forgot to interpolate the solution of the coarser grid and so I interpolated it after 128 iterations. The residuals of my species made a big jump to 1e+20 and stay now at 1e+17. The other residuals are now between 1e-3 and 5e-3, but the calculation is still not completely converged. I never saw such a phenomenon with the Pressure Based Coupled solver and the residuals on the coarser grid were also lower with this solver ( between 5e-6 and 3e-8 ).
I am using the Density Based Solver and the Pressure Based Coupled solver, because I calculate a supersonic flow (M~2.2).
Do anyone know the reason for this residual-phenomenon and why they are still so high? And perhaps the reason, why the residuals of the Desity Based Solver - in my cases - are always greater than the residuals of the Pressure Based Solver?

Thank you very much!