convergence problem
 

Hi, everyone, i am dealing with the mixing problem in a stirred tank. I used MRF method to simulate the mixing situation, the biggest problem now is the both the mass and momentum can not get the convergence criterior (momontum around 10-3,and mass around 10-4). when it gets to the certain computation steps, the values will not change any more...
how to solve this problem...

Thanks in advance for every help.
Best regards, Lily

Residuals are not a good criterion....Try monitoring variables instead: maybe u have alerady convergence.
Anyway,u can refine ure time step or change ure turbulence model....Refining ure mesh is also appreciated
Regards