Hi everyone!

I am going to simulate supersonic flow with the mach number of about 2.0 using CFX 11.0. But I am not familiar with the supersonic flow. Can anyone tell me at what range of mach number the CFX solver can give reliable results?

Thanks in advance!

Mach 2 should be fine. Some tips: Set expert parameter max continuity loops = 2 Start run with local timestep. Once converged switch to physical timestep (if problem is steady) Use SST turbulence model

Thanks for you advise, Bart.

Regards, Lan

Sometimes I get funky residuals from the energy equation using max continuity loops = 2. You might try starting the simulation with less aggressive BCs for subsonic flow to give CFX a chance to resolve the flowfield. Once you have a converged subsonic result you can step up gradually to your supersonic boundary conditions. This will help aid convergence.

John

John,your advice helps me a lot.

Thank you very much!

Hi,

In my experience all of these suggestions are problem dependent - I have never found the max cont loops to help but I have found starting with local timestepping and switching to physical timestepping after things settle down a bit works well. Obviously you will have to try them on your simulation and see what works.

Glenn Horrocks