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-   -   How to determine the separation point on an airfoil??? (http://www.cfd-online.com/Forums/main/101343-how-determine-separation-point-airfoil.html)

mohammad May 1, 2012 23:39

How to determine the separation point on an airfoil???
 
Hi everybody.
I have solved a 3D blade. I want to extract the location of separation point from the results.

Which parameter best shows the Separation Point ? I remember it was one of stress component but i don't remember it clearly.

Regards,

truffaldino May 2, 2012 04:39

Quote:

Originally Posted by mohammad (Post 358733)
Hi everybody.
I have solved a 3D blade. I want to extract the location of separation point from the results.

Which parameter best shows the Separation Point ? I remember it was one of stress component but i don't remember it clearly.

Regards,

This is a point where tangential (shear stress) force vanishes. This is the point where dv_t/dn=0, where v_t is tangential velocity and n is coordinate normal to the surface

mohammad May 2, 2012 04:47

Quote:

Originally Posted by truffaldino (Post 358776)
This is a point where tangential (shear stress) force vanishes.

Hi truffaldino,
I know that it must be shear stress...and in CFD we have the "shear-wall- stress" for that. My question is that which of the "sheat-wall- stresses"( X,y,z) or the resultant ??

truffaldino May 2, 2012 05:27

For flows which are not quasi 2D: the 3D boundary layer flow the point of separation is not necessarily a point of zero surface stress

For more details see this forum

http://www.cfd-online.com/Forums/mai...w-problem.html

If your flow is quasi 2D, then the separation/reattachment lines will be approximately at the minimum of absolute value of the shear stress


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