|July 21, 2011, 04:39||
GAMG vs. PCG in fvSolution
Join Date: Oct 2010
Posts: 35Rep Power: 8
i'm working with two domains of exactly same geometry and case configurations. one domain has 150000 cells, the other about 6*10^6 cells.
in the coarse domain case the GAMG solver needs about 30 iterations for one timestep (nCellsInCoarsestLevel = 1000). on the other hand, if i choose PCG the calculation needs 230 iterations.
in the fine domain case it's the opposite: PCG needs about 1000 iterations but GAMG does need more (maxIter limitation at 1500, various nCellsInCoarsestLevel).
what's your experience with GAMG? any tips what i could try?
|November 13, 2015, 09:58||
Antony Ashley Raja B
Join Date: Jul 2015
Posts: 16Rep Power: 3
Did you find any answer?
I am solving a external flow simulation. When i increase the number of layers and decrease the min thickness close to 9.6e-06,in a GAMG solver the iterations reach close to 1000 and crashes but on the other hand PCG works very well.
Is there any reason behind.
|March 7, 2017, 08:38||
Join Date: Mar 2015
Posts: 237Rep Power: 5
Thanks for opening this topic. I have two suggestions:
1) Some people here on the forum say nCellsInCoarsestLevel shouldn't be above 50. On my cases I always make sure to make a "nCellsInCoarsestLevel-study".
2) I think your post would be even more meaningful if you would tell us the calculation time/iteration or per timestep. The number of iterations alone is not so meaningful from my point of view.
|Thread||Thread Starter||Forum||Replies||Last Post|
|Velocity blows up suddenly after 30,000+ iterations||lordvon||OpenFOAM Running, Solving & CFD||15||October 19, 2015 13:52|
|GAMG solver causes troubles||colinB||OpenFOAM Running, Solving & CFD||5||June 13, 2013 07:48|
|Floating point exception error||Alan||OpenFOAM Running, Solving & CFD||10||April 6, 2012 14:02|
|Problems with simulating TurbFOAM||barath.ezhilan||OpenFOAM||13||July 16, 2009 05:55|
|Differences between serial and parallel runs||carsten||OpenFOAM Bugs||11||September 12, 2008 11:16|