[求助]divergence detected in AMG solver:

freeairxue

计算时出现“divergence detected in AMG solver:spcies－0”或者“divergence detected in AMG solver:temperature”这是怎么回事呀
计算模型为层流模型，组分疏运
问题出在网格还是其它的呢？

梅花雪剑

或许网格，或许边界条件，[br][br][以下内容由 梅花雪剑 在 2008年02月01日 09:21am 时添加] [br]
转贴：
Divergence in AMG solver :k
Posted By: Guillaume <baudryg@hotmail.com>
Date: Thu, 6 Jan 2005, 2:19 a.m.
I try to study the turbulence inside a vertical cylinder. In a first time, I take the case of steady flow. The air is introduced axially from below, deflected by means of a small conical deflector and thanks to the geometry of the chamber the air goes up into the cylinder. I take the ideal gas law, k-epsilon model, inlet and outlet pressure for boundary conditions.
My problem is that I have directly the message "divergence detected in AMG solver : k" when I want to iterate.
I try a lot of solutions I have find in this forum without any result.
Could anyone help me?
Thanks in advance
Check your hardware, especially RAM sockets. I have experience, that this could be initiated by some bad memory address sectors.
I had a similar problem, but with pressure correction. I found that I had some highly skewed cells. Once I corrected the highly skewed cells by adapting the iso-values of cell skewness my case began to iterate. Perhaps this may be your problem. First initialize the solution and then go to contours grid and select equiangle skew and click compute to get you min and maxs. Having skewed cells of 0.9 or higher isn';t good, as in my case. Hope this helps
I have check the skewed cells but it appears that in my case, this number is lower than 0.4 Is it to high?
divergence in AMG solver
Posted By: Steffen <st.reising@gmx.de>
Date: Mon, 22 Nov 2004, 6:38 a.m.
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
Try to use more conservative Under-relaxation factor.
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
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
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
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 didn’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.
My mesh is quite fine, but I will try more finer mesh. Thanks
then it shall converge ..anyway have you tried using segregated solver, how the results with that
Error: Divergence detected in AMG solver?
Posted By: frank
Date: Sun, 16 Jan 2005, 3:58 p.m.
What does mean and how do i fix it? I am runing a rosseland radiation model and it wont run past 1 iteration.
Frank
you are using the segregated solver, so you must reduce the under relaxation factor as you can.
You could have a grid issue concerning high skewness. This can be checked by going to contours grid cell equiangle skew and select compute and check the min and max. You should be below .9. If over t5hen this could be your problem. It has happened to me a couple of times.
thanks a million i will try this...
frank
AMG solver: k divergence?
Posted By: Robert <r_carson22@yahoo.com>
Date: Sun, 9 Mar 2003, 11:23 a.m.
How do I remedy a divergence with this message. This is for scramjet combustion in 2D with injectors on both the top and bottom. Is there any way to look up error messages?
reduce underalaxtion factor.
I have tried reducing the underelaxation factors but the divergence persists. Any other suggestions? Perhaps in the AMG solver Menu?
It looks like a problem with your boundary conditions, be sure they';re compatible with each other and consistent with the physics of what you';re trying to simulate,
I think you';d better don';t touch anything in the AMG menu, unless you know exactly what you';re doing,
It is my opinion, if this could help.
Have a nice day,
Jkl.

braveman

好不容易看完啦，太累啦！不过还要谢谢。