Hi,

I am trying to simulate an Impeller alone (no inlet and discharge volutes) in CFX11. Its a single component simulation, something similar to what bladegen plus used to do. I have the impeller geometry as a rotating domain with the inlet & outlet slighly extended. Inlet BC is Total Pressure and Outlet is the mass flow rate. As the inlet to the domain has been slightly extended (in actual reality it would be stationary) hence i have applied a Counter rotating wall on that surface.

The simulation does go thru well, and results such as Head are satisfactory.

But is the physics correct? Does CFX simulate Single component rotating domain correctly, incase one is not considering Upstream or downstream effects. Can I continue to use this method for quick changes rather than using MFR?

Yes!

I mean Yes to all your questions. Your procedure is correct.

Thanks Mic for your reply, I was trying to evaluate the effect of Surface finish on performance on an impeller. I did the simulations as per above said method and there was hardly any change in performance with increasing Ra values. I contacted CFX support to see if their was something wrong with my setup, I expected some comments on my mesh, but the reply I got was that the setup of the problem was wrong. They suggested that I should be performing MFR with the inlet portion included. They also didnt fully agree with the counterrotating wall. Can someone let me know if the MFR simulation would make any difference to my simulation results assuming that I use similar BC's with a striaght inlet pipe?