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-   -   Under-relaxation factors (http://www.cfd-online.com/Forums/fluent/36320-under-relaxation-factors.html)

pUl| April 8, 2005 17:35

Under-relaxation factors
 
I know that a converged solution is independent of the value of URF's chosen. However, is it acceptable to change URF's in the middle of a solution and then continue iterating?

ap April 9, 2005 07:49

Re: Under-relaxation factors
 
Yes it is acceptable.

You're right when you say that a converged solution does not depend on the value of URF's, but the convergence of a solution is dependent on their values, and also by the combination of them.

Some authors like Peric, for example, suggests some rule of thumb like

a_velocity + a_pressure = 1

where a represents the URF.

Regards, ap

swarup April 9, 2005 10:22

Re: Under-relaxation factors
 
regarding URF's,can excessive under-relaxation introduce accuracies in unsteady flows. that is, although solution will be converged but not accurate?

Swarup.

pUl| April 9, 2005 13:55

Re: Under-relaxation factors
 
Thanks Swarup, You meant "introduce inaccuracies" right?

pUl| April 9, 2005 13:56

Re: Under-relaxation factors
 
Thanks for the information ap. Very well worded indeed!


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