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under-relaxation factors -> level of residuals

Posted August 27, 2012 at 10:27 by kira

more helpful info on under-relaxation factors:

Quote:
Originally Posted by LuckyTran View Post
No magic here, that's what's supposed to happen. Unless your solution is diverging, do not bother with the under-relaxation factors. If it is diverging, do as you did, lower the factors until you can a stable solution, and then raise them again if possible. If not, then it is a hint that there is an inherent stability issues in the problem you are trying to solve or perhaps one of your modeling parameters is incorrect.

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Old

what is under relaxation factor?

Posted August 27, 2012 at 10:23 by kira

something to keep in mind:
Quote:
Originally Posted by Phil
;140717
Each of the variables(mass,mom,density) represents an equation the solver is trying to solve. Each iteration the values obtained for the variables should get closer and closer together - converge. FOR SIMPLE PROBLEMS ESPECIALLY COLD FLOWS WITHOUT COMBUSTION YOU SHOULD SIMPLY KEEP THE RELAXATION FACTORS AT DEFAULT.

Sometimes for many many reasons the solution can become unstable so a relaxation factor is used - takes part of value from previous iteration
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