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-   -   Statistic averaging and Periodic BC Fluent/Gambit (http://www.cfd-online.com/Forums/ansys/90264-statistic-averaging-periodic-bc-fluent-gambit.html)

truffaldino July 5, 2011 18:55

LES Statistic averaging and Periodic BC Fluent/Gambit
 
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Hello,

I am running LES with FLUENT for a wing: basically this is 2D x-y-airfoil translated by 0.2 of its chord in z-direction with periodic BC imposed in z-direction.

After gathering statistics I got this strange averaged plot of Cp(x): there are some strange spikes at the sucion side closer to the trailing edge
(as you could see on the image attached).

It seems to me that it is not physics at the origin of tese spikes, but some software problems.

I had troubles to make periodic mesh with GAMBIT using automatic boundary layer generation, but then repared periodic conditions with help of FLUENT:

http://www.cfd-online.com/Forums/flu...dow-faces.html

http://www.cfd-online.com/Forums/ans...riodic-bc.html

Might it happen that this "reparation" was not complete? It is seen on the plot that spikes occur once at each cell/or perhaps between cells on cell faces.

On the other hand, I have these spikes only on a part of airfoil where separation/transition and big fluctuations occur,
so it might be also problem of statistic averaging.

I will be grateful for your help.

Truffaldino


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