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-   -   NACA airfoil with LES (http://www.cfd-online.com/Forums/cfx/93033-naca-airfoil-les.html)

Roland R October 3, 2011 09:21

NACA airfoil with LES
 
Hello,

I would like to investigate an NACA airfoil with LES. My computer capacity is not too large and I have to calculate a lot of cases. Therefore I would like to study 2D cases only. I know that the 2D simulation is not too correct in case of LES but at the moment there is not other possibility. So if I apply the LES then my result is total bad or it will contain fewer information than in case of 3D ?

Thanks
Roland

ghorrocks October 3, 2011 17:42

You cannot do LES in 2D. It is an inherently 3D approach. If you do not have the computing resources to proceed then give up until you do. 2D LES will be a waste of your time.

cfd_newbie October 4, 2011 01:05

Quote:

Originally Posted by Roland R (Post 326494)
Hello,

I would like to investigate an NACA airfoil with LES. My computer capacity is not too large and I have to calculate a lot of cases. Therefore I would like to study 2D cases only. I know that the 2D simulation is not too correct in case of LES but at the moment there is not other possibility. So if I apply the LES then my result is total bad or it will contain fewer information than in case of 3D ?

Thanks
Roland

You may do a kind of pseudo 2D where you will extrude your 2D airfoil to some length, this way you would be able to compare your CFd results with that of 2D experimental data.

See the link where similar topic has been discussed earlier -
http://www.cfd-online.com/Forums/main/89070-des-2d.html

ghorrocks October 4, 2011 01:14

You can run a 2D LES but your results will be rubbish. You are constraining the third dimension and the turbulence energy cascade will be completely corrupted. LES is inherently 3D and you cannot do it in 2D and hope for results which are close to reality.


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