Doubt in OpenFOAM

Tushar@cfd · June 2, 2014, 07:23

Dear Foamers,

I have a doubt in OpenFOAM:

Q) What is the advantage of using relaxation factor for both fields & equations? How accurate will be the solution?

Q) How these relaxation factors are determined (for example: p="0.3" & U="0.7")? Will it affect the solution accuracy?

mechy · June 4, 2014, 02:34

these relaxation factors stand for better convergency and do not affect the acuracy

Tushar@cfd · June 4, 2014, 02:57

Thanks for the reply,

As per algorithm, it appears only equations needs under-relaxation. I was actually confused between field & equation. Anyways, these are important for convergence.

mechy · June 4, 2014, 03:06

please take a look at UEqn and pEqn of simpleFoam solver.
for U the equation is relaxed ( UEqn().relax())
but p is relaxed explicitly ( p.relax())

June 2, 2014, 07:23	Doubt in OpenFOAM	#1
Tushar@cfd Senior Member T. Chourushi Join Date: Jul 2009 Posts: 321 Blog Entries: 1 Rep Power: 18	Dear Foamers, I have a doubt in OpenFOAM: Q) What is the advantage of using relaxation factor for both fields & equations? How accurate will be the solution? Q) How these relaxation factors are determined (for example: p="0.3" & U="0.7")? Will it affect the solution accuracy?

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June 4, 2014, 02:34		#2
mechy Senior Member Join Date: Jun 2011 Posts: 163 Rep Power: 15	these relaxation factors stand for better convergency and do not affect the acuracy

June 4, 2014, 02:57		#3
Tushar@cfd Senior Member T. Chourushi Join Date: Jul 2009 Posts: 321 Blog Entries: 1 Rep Power: 18	Thanks for the reply, As per algorithm, it appears only equations needs under-relaxation. I was actually confused between field & equation. Anyways, these are important for convergence.

June 4, 2014, 03:06		#4
mechy Senior Member Join Date: Jun 2011 Posts: 163 Rep Power: 15	please take a look at UEqn and pEqn of simpleFoam solver. for U the equation is relaxed ( UEqn().relax()) but p is relaxed explicitly ( p.relax())