Hi, i'm analysis turbomachinery that air compressor its rpm is 120,000 and flow rate is 0.06kg/s i iterate over 500 but it's not converged, and risiduals oscillation

what is the problem in my case? plz advise me...

I think you will have to run unsteady case for your problem. Thats what oscillation of residuals indicate.

Usman

Thx Usman.

i think that if i do unsteady simulation this case it will be take very long time becasuse it's rpm is over 120,000rpm so time step will be very small for corant number.

Well, pls tell me your geometry of your compressor, I think you are running at a point well beyond surge point. Looks like you are working on a project very similar to mine. MInd to tell me about you and your work? Thanks

Hi,

This question has been asked hundreds of times before. Look at the FAQ:

http://www.cfd-online.com/Wiki/Ansys...gence_criteria

Glenn Horrocks

Thx Glenn.

and I will more carefull before wirete question...