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February 26, 2013, 14:46 |
problem with convergence
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#1 |
Member
Join Date: Sep 2012
Posts: 40
Rep Power: 13 |
I am having trouble getting my residuals to converge to the specified criteria. At first I set it to 1e-06 and did over 10000 iterations and it didn't converge. Then I tried 1e-04 and it didn't converge. Now I am trying 0.01 just to see if my solution will converge and still it hasn't. It seems like anything I try with any example or problem I have done in Fluent my solution never converges.
The x,y,z velocity fluctuate around 1e-2 and currently I am over 2600 iterations. Does anyone know why my solution may not be converging? |
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February 27, 2013, 11:34 |
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#3 |
Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,399
Rep Power: 46 |
Without ANY information about your setup, how are we supposed to guess what causes your problem.
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February 27, 2013, 13:09 |
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#4 |
Senior Member
A-A Azarafza
Join Date: Jan 2013
Posts: 226
Rep Power: 14 |
As Alex said, you can't definitely speak about convergence without have any information regarding to problem setup, but as I've experienced many times, most of the problem in starting a simulation is due to mesh quality, except that you apply proper physical properties and boundary conditions. So, my first advice is that you check the mesh quality and existence of any probable undesired wall especially in your flow path.
Hope it could be helpful |
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February 27, 2013, 15:29 |
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#5 |
Member
Join Date: Sep 2012
Posts: 40
Rep Power: 13 |
Ha. Sorry I didn't provide much information. I was just looking for some general answers as why problems usually don't converge.
My mesh is 0.1m. I know this is really big but I was just starting out big and goingto work my way down. So I guess my question is, if my mesh is too big will my solution never converge? Thanks for everyones replies! |
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April 11, 2013, 04:46 |
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#6 |
Senior Member
A-A Azarafza
Join Date: Jan 2013
Posts: 226
Rep Power: 14 |
Maybe you'd better use a finer mesh, but, as far as I know you wouldn't face a dead problem as long as your simulation involves only hydrodynamic, though the accuracy simulation is low. However, mesh independency analysis reveals enough number of cells for your case but for species transport or reaction you need to use a very finer mesh.
__________________
Regard yours |
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April 11, 2013, 08:56 |
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#7 |
Member
James Willie
Join Date: Mar 2009
Posts: 81
Rep Power: 17 |
What type of problem are u looking at? The physics of the problem is important in addition to the mesh resolution you are using. Throwing more light might help us help you. Thanks! Jimmy
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