rhoPimpleFoam algorithm
I am working in OF v1.7.1 and have a couple quick questions regarding the implementation of the compressible PISO-SIMPLE algorithm:
1) On line 00095 of the rhoPimpleFoam/pEqn.H code: Why is the if statement commented out? Should the relaxation of pressure really be allowed in the final outer iteration? Quote:
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Hi,
you are correct, there should be no relaxation in the last iteration because otherwise you get a continuity error (which is very large if you look at the tutorial case). I'm not sure about the energy equation but would be interested in your result. Regards, Christian |
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However this aspect might influence convergence rate, but it should not affect the results. Best, |
Alberto and Christian,
Thank you for entertaining my curiosities. I will let you know anything I find through experimentation, though it seems as if Alberto does not expect much difference on either point. For the interested foamer stumbling across this thread, I suggest reviewing the following thread for a more involved discussion of relaxation http://www.cfd-online.com/Forums/ope...ime-steps.html Regards, Perry |
Yes, I do not expect any difference on the solution.
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Best, |
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this commented-out IF statement has been removed from OF v.2.4, as can be seen here: https://github.com/OpenFOAM/OpenFOAM...oam/pEqn.H#L92 I am getting massive timestep continuity errors and no pressure convergence for what should be a very straightforward problem of orthogonal mesh and subsonic gas flow. After searching a lot in this forum (and it is quite hard to get the keywords right!) I think that if I don't relax the pressure in the last outer iteration my solution may converge. Has anyone tried to do this in newer versions of OF? Anyone know why the commented out section was removed? Can you please guide me to where OF explains changes from one version to the next? Thanks, Christa |
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