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gregor.vidmar153 August 27, 2010 10:07

Under-relaxation of PISO
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,


sharonyue September 3, 2013 02:57

UEqn.relax() exists in pisoFoam. but there is no p.relax(), Im confused too. Did you find a solution?

gregor.vidmar153 September 3, 2013 03:09

Not yet, unfortunately.

With regards.


Houthuys June 9, 2017 04:16

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

sharonyue June 9, 2017 04:55

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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