RSM can not converge !?

Conan · September 16, 2009, 02:38

For my geometry in FLUENT, when I choose standard/RNG/Realizable k-e model, the iiteration can converge. BUT when I choose RSM, the iteration can NOT converge. It happens some errors after several iterations(less than 10).

How to fix the problem? Thanks

tstorm · September 16, 2009, 11:59

This is a common problem with the RSM model - the Reynolds stress equations are highly coupled, making convergence difficult. Try reducing under-relaxation factors and the courant number. If those don't help, I've had some luck with multi-gridding and residual smoothing.

Most likely though, if UR factors and courant number don't fix the problem, then you should make sure your grid is sufficiently fine and the cell qualities are excellent. The RSM model is finicky.

September 16, 2009, 02:38	RSM can not converge !?	#1
Conan New Member gnxie Join Date: Mar 2009 Location: Sweden Posts: 16 Rep Power: 17	For my geometry in FLUENT, when I choose standard/RNG/Realizable k-e model, the iiteration can converge. BUT when I choose RSM, the iteration can NOT converge. It happens some errors after several iterations(less than 10). How to fix the problem? Thanks

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September 16, 2009, 11:59		#2
tstorm Member Join Date: Apr 2009 Posts: 78 Rep Power: 17	This is a common problem with the RSM model - the Reynolds stress equations are highly coupled, making convergence difficult. Try reducing under-relaxation factors and the courant number. If those don't help, I've had some luck with multi-gridding and residual smoothing. Most likely though, if UR factors and courant number don't fix the problem, then you should make sure your grid is sufficiently fine and the cell qualities are excellent. The RSM model is finicky.