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-   -   divergence in AMG solver (http://www.cfd-online.com/Forums/fluent/35129-divergence-amg-solver.html)

Steffen November 22, 2004 09:38

divergence in AMG solver
 
Hi. I have a simulation of a supersonic-valve running but the program shows me this message: divergence detected in AMG solver: temperature

I tried to rise the limits for temperature and other solution limits but nothing has helped so far

Does anyone what to do

thanx

Umesh November 22, 2004 11:24

Re: divergence in AMG solver
 
Try to use more conservative Under-relaxation factor.

Luca November 22, 2004 13:21

Re: divergence in AMG solver
 
I had the same problem with a wing in a transonic flight. According to me the segregated solver is not suitable for the conditions with high compressibility. Let me know if you succeed in using the segregated and how... I suggest using the coupled solver,Your problem will vanish... Hope to hear good news from you soon. Luca

zxaar November 22, 2004 20:32

Re: divergence in AMG solver
 
this will be something wrong with the either boundary condition or with model selection, generally if things are right fluent just converges fine without any warning or problem. in my opinion these are the signs that you are doing something wrong in settign up the case, look closely

Aftab November 30, 2004 16:37

Re: divergence in AMG solver
 
Hi, I have the same problem, and could n't solve it by using the coupled solver. Is there any other possible way. I am simulating office room problem. It seems very simple but on every stage it is creating problems for me. I am going to try to change the underrelaxation. lets see what comes up. Thanks

zxaar November 30, 2004 20:08

Re: divergence in AMG solver
 
long ago, one of my friend was doing CFD analysis of a kitchen,, using coupled solver, and he faced the same problem, for some time he din't get the converged results. finally when i looked at his mesh. it seemed the problem is with the mesh not with the solver settings. i suggested him to make mesh more finer, and viola it gave results in one run, without any problem. so moral of the story check your mesh.

Aftab December 1, 2004 09:54

Re: divergence in AMG solver
 
My mesh is quite fine, but I will try more finer mesh. Thanks

parth December 1, 2004 18:32

Re: divergence in AMG solver
 
then it shall converge ..anyway have you tried using segregated solver, how the results with that


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