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-   -   CFX Solver Control, Max iteration (https://www.cfd-online.com/Forums/cfx/101844-cfx-solver-control-max-iteration.html)

adilsyyed May 15, 2012 11:43

CFX Solver Control, Max iteration
 
I am doing a steady state analysis.
I have given maximum iterations in solution control to be 10000 with physical timescale of 5 sec.
The solver gives me result in 55 iterations, and does not go for the whole 10000 iterations.
Why?
And before this, in the very same analysis, I just specified maximum iterations to be 1000 with 2 sec physical timescale, and the solver go up to complete 1000 iterations.

evcelica May 15, 2012 12:10

Did you reach your convergence criteria? That would also stop the run.

k.vafiadis May 15, 2012 13:06

Check what's the convergence criteria: RMS or MAX Residual Target. Also, check the way you define your Timescale.

adilsyyed May 15, 2012 13:32

Quote:

Originally Posted by k.vafiadis (Post 361251)
Check what's the convergence criteria: RMS or MAX Residual Target. Also, check the way you define your Timescale.

RMS, RMS target 0.0001

And what do you mean by he way I define your Timescale?

k.vafiadis May 16, 2012 04:32

A reasonable physical time scale value selection is important for good and faster convergence.
So for time scale 2sec and RMS target 10^-4 the solver needed 10000 (or more?) iterations to converge.
But with time scale 5sec and RMS 10^-4 the solver converged (converged to your RMS target) with only 55 iterations.
According to CFX Solver Modeling Guide (Chapter 14), physical time scales that are too large are characterized by bouncy convergence or results that do not converge. Time scales that are too small are characterized by very slow, steady convergence.


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