Hello

I am simulating a problem using upwind scheme. I have used a local time step factor of 0.9. If I do this the velocities (all u,v,w) and energy residuals come below the required 1e-5 and attains the steady value where as the RMS mass residual suddenly becomes infinity after a few iterations and continues to be like that.At this stage if I change the continuity equation from local time step factor of 0.9 to a physical time step or auto time step the RMS mass residual suddenly becomes zero and the problem becomes converged. In the beginning if I give a physical time step the problem diverges. Kindly let me know why this happens.

Thanks

Hi,

I suspect your simulation is not physically valid, or your mesh quality is poor or some other setup problem. This FAQ may also be of assistance http://www.cfd-online.com/Wiki/Ansys...gence_criteria

Glenn Horrocks