I am doing the steady state analysis for comprissible flow I have a pboblem of mass convergance I am getting the convergance for all the residual except the mass residual which is fluctuating in between 0.1 to 0.01 continuosly between iteration 300 to 1200 while at 1000 iteration i got the convergance for all other residuals Can anybody help me to resolve this problem.

Regards

Kale

Try to decrease the under-relaxation factors of pressure equation. sometimes it may be lower as 0.01 to get the convergenced solution.

And if this doesn't help, It's possible that your geometry provokes an unsteady (oscillating) flow field in spite of the steady BC's. Is it by any chance a wide-angled diffuser....

Lars Ola