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note about convergence
Posted March 26, 2013 at 04:39 by skeptik
Quote:
Originally Posted by chegdan
Nick,
There are some strategies that I would try to get these residuals down to something you would like.
There are a lot of other strategies that you can try, but this one might be sufficient. Without knowing more details like divergence schemes; mesh structure and checkmesh results; y+ values; and boundary conditions there is not much to add on my part.
I would look at the thread http://www.cfd-online.com/Forums/ope...-problems.html and then move on to a search of the forum. There are many threads about simpleFoam convergence...but my list of threads is not in front of me right now. good luck.
There are some strategies that I would try to get these residuals down to something you would like.
- Lower your pressure relTol by an order of magnitude compared to U i.e. relTol = 0.001 for P and relTol = 0.01 for U.
- Without knowing the mesh you are using you may need to increase the nonorthogonal corrector by 1 or 2. if you are using a tet mesh...then there are many things you can do.
- Use first order schemes to start with (you will move to higher order ones later)
- Obtain an initital velocity field with potentialFoam
- Using simpleFoam, the intial condition from potentialFoam, and first order schemes...turn turbulence OFF and once convergence seems to bottom out, turn turbulence on while the simulation is running
- Once a steady-state is obtained, stop the simulation, switch to second order schemes and restart the simulation with turbulence on and see if that helps
There are a lot of other strategies that you can try, but this one might be sufficient. Without knowing more details like divergence schemes; mesh structure and checkmesh results; y+ values; and boundary conditions there is not much to add on my part.
I would look at the thread http://www.cfd-online.com/Forums/ope...-problems.html and then move on to a search of the forum. There are many threads about simpleFoam convergence...but my list of threads is not in front of me right now. good luck.
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