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-   -   Fluent 6.3 first run (http://www.cfd-online.com/Forums/fluent/43015-fluent-6-3-first-run.html)

Michael B December 4, 2006 09:53

Fluent 6.3 first run
 
Hi. I did my first official 6.3 Fluent calculation today. I started out with the old segregated solver on my case and after som 100 iterations i switched to the promising coupled solver, but the result was not as good as expected.

<table style="width:auto;"><tr><td>http://lh5.google.com/image/michaelb...led_solver.jpg</td></tr><tr><td style="font-family:arial,sans-serif; font-size:66%; text-align:right">From fluent6.3</td></tr></table>


Ahmed December 5, 2006 00:06

Re: Fluent 6.3 first run
 
What is your question.

Convergence was flat before switching to the coupled solver and after

Jason December 5, 2006 06:31

Re: Fluent 6.3 first run
 
Try using the FMG initializer (TUI command: s i fmg y) and skip using the segregated solver, go straight to the coupled one.

Good luck, Jason

Riaan December 5, 2006 11:33

Re: Fluent 6.3 first run
 
Careful - the coupled solver does not do well with flow separation.

Jason December 7, 2006 09:32

Re: Fluent 6.3 first run
 
There's limitations to all of the solvers. The pressure based coupled solver still doesn't do as well at supersonic flows as the density based coupled solver, and either of the pressure based solvers do better in the low Mach number regimes compared to the density based solver. The density based coupled solver would choke on separated flows in any flow regime. I haven't gotten an opportunity to try the pressure based coupled solver with separated flows. I thought the main problem with separated flows for the old coupled solver was the small density gradients. Was the calculation of separated flows improved with the pressure based coupled solver, or is it inherent in all coupled solvers?

Thanks, Jason

zxaar December 7, 2006 19:50

Re: Fluent 6.3 first run
 
I tried pressure based coupled solver (CFX) for seperated flows and I must say I am not happy. (CFX users might be happy with it though).

Jason December 11, 2006 09:41

Re: Fluent 6.3 first run
 
Thanks for the input! Jason

zxaar December 11, 2006 18:29

Re: Fluent 6.3 first run
 
I have a feeling that anysys might abandon CFX (or it might be lost in oblivian), the reason for thinking so is. We have seen pressure based coupled solver in Fluent. Than CFX has transition models for turbulence. Fluent has introduced transition model in 6.3 as beta function. So slowly we are seeing shifting of features from CFX. In the end ANSYS might not have any reason to develop CFX any further if Fluent can do the job. Good thing now is Fluent provides a lot of choices in terms of solvers.



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