Residuals in PimpleFoam

Triggin · May 14, 2018, 06:37

Hi all

I have a very basic question:
What is a typical residuals behaviour for a converging pimpleFoam solver?

I think my simulation converges (see attachment), since the final residuals of the simple-iterations continuously decrease.
However, the initial residuals of the PISO-algorithm remain at a high level...

Is this a typical behaviour?

Any experience on this is very welcome
Best, Triggin

LuckyTran · May 21, 2018, 16:58

Is indeed typical behavior.

The residual goes haywire on the final iteration because this one has no under-relaxation urf = 1. In a converging PIMPLE solver, you never make it to the final PISO step and exit while still in SIMPLE mode.

Bazinga · June 7, 2018, 08:50

Just to add to the answer, here is a link which might also be helpful for you understanding the residuals

http://openfoamwiki.net/index.php/Op...hm_in_OpenFOAM

June 7, 2018, 08:50		#3
Bazinga Senior Member Join Date: Jun 2012 Location: Germany, Bochum Posts: 230 Rep Power: 16	Just to add to the answer, here is a link which might also be helpful for you understanding the residuals http://openfoamwiki.net/index.php/Op...hm_in_OpenFOAM Tj_m3, Roxana_Laspiur and pickfirst like this.

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May 21, 2018, 16:58		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	Is indeed typical behavior. The residual goes haywire on the final iteration because this one has no under-relaxation urf = 1. In a converging PIMPLE solver, you never make it to the final PISO step and exit while still in SIMPLE mode.