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Under-relaxation of PISO

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Old   August 27, 2010, 10:07
Default Under-relaxation of PISO
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Gregor
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I'm interested in what actually does UEqn.relax() in pisoFoam ?
It stabilized (accelerated) my comptutation of the thermo flow in a channel and the phase change liquid-solid a lot, but I do not know if the solution is correct, I mean the transient solution, not the steady-state one.

Thanks for any help,

Gregor
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Old   September 3, 2013, 02:57
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Dongyue Li
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UEqn.relax() exists in pisoFoam. but there is no p.relax(), Im confused too. Did you find a solution?
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Old   September 3, 2013, 03:09
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Not yet, unfortunately.

With regards.

G.
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Old   June 9, 2017, 04:16
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It's an old thread but I also can't find an answer.

Do any one know why we have Ueqn,relax() in pisoFoam which is a transient solver ?

Also when we should use equation relaxation (Ueqn.relax()) and explicit relaxation (p.relax)?

Any contribution is highly appreciated
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Old   June 9, 2017, 04:55
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Dongyue Li
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No matter SIMPLE, PISO, SIMPLEC or others, you can UEqn.relax(). However, you can not p.relax() for PISO. But p.relax() works for SIMPLE and SIMPLEC.

See Peric page 177.
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