|July 28, 2012, 17:52||
Need help on my CFD homework. RMS fluctuates.
Join Date: Jul 2012
Posts: 494Rep Power: 8
I simulated a case by CFX-solver. But the RMS value does not converge. The mesh quality is above 0.5 at ICEM. I set the timestep very small to 0.001s. (Initially it was larger, but there's still RMS fluctuation for nearly every timestep.) I copied the boundary condition setting from my classmate. It's not likely to have any problem at it. Since I'm not allowed to distribute our homework, I can only upload my CFX-solver pictures. Hope you can give me some hints about where the problem might be.
Last edited by Anna Tian; July 29, 2012 at 04:06.
|July 29, 2012, 07:24||
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,638Rep Power: 98
This question is a FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria
As the residuals do not oscillate it is unlikely to be transient flow. Much more likely mesh quality (ie remesh with better quality mesh) or numerical precision (ie try double precision).
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