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Marat Hoshim October 23, 2000 03:37

Momentum coefficient of airfoil flow
 
Hi all,

studying some papers about the calculation of airfoil flow I have got the impression that standard k-eps model with wall function is not suitable at all for that case. Especially when it comes near the stall angle. Even low-re versions of k-eps model do not give accurate results because separation on the suction side is surpressed often. Could someone tell if my impressions concerning that topic are rigth ? Improvement was shown by using k-w models because separation is better captured. Could one also expect improvement when using k-w model with wall functions ? In papers the improvement is mostly shown on the values of cd and ca. Does someone know if I can expect the same improvement for the momentum coeficient ?

Any comment on that are appreciated !

Marat

sylvain October 23, 2000 13:31

Re: Momentum coefficient of airfoil flow
 
Hi,

You're right, RANS models often fail to predict the stall angle.

The Wilkox's k-omega model seems to give better prediction in some case as other model like the Spalart-Almars's one equation model. I think there was an Ercoftac Workshop one or two days ago, organized by TUdelft, where one of the test case was an Aerospatial-A airofoil at 13.3 degre. At this angle a recirculating flow appears on the suction surface and most of the usual turbulent models don't predict it.

I'm not sure that the k-omega turbulence model was design to be used with wall function.

Sylvain


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