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ga5aq July 12, 2010 10:54

optimal probe position for convergence
 
Hi all
following from my previous thread (drag calibration of cube) does anyone know if convergence can be reached while the probe is within a turbulence area behind a Cube (in my case)?

As it doesn't seem to converge after a day's iteration

any views will be greatly appreciated
G:cool:

Welshnathan April 12, 2011 18:29

Hi ga5aq,

What is your global convergence criterion set at?

I was not aware that the probe position would impact the speed of convergence? If this is the case, I would not recommend placing it in the turbulent region.

Have you tried feeding your variable values obtained in a given run, back into a new run?
This can be done at the initialisation section. The following has been taken from the PHOENICS help documentation (POLIS):
'If one knew the solutions to the equations at the start, and could insert the corresponding variable-field values as initial guesses, convergence would be immediate. Of course, the solutions never are known; however, if initial guesses can be made which are close to these solutions, convergence is likely to be rapid.'

This should save you some time instead of waiting for 12 hours to reach the same level of convergence every run.

Also, check out the Polis section on convergence:
http://www.cham.co.uk/phoenics/d_pol...nc/converg.htm

Hope this helps.


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