# How to determine the separation point on an airfoil???

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 May 1, 2012, 23:39 How to determine the separation point on an airfoil??? #1 Senior Member   mohammad Join Date: Dec 2010 Location: UK Posts: 245 Rep Power: 16 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,

May 2, 2012, 04:39
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 Originally Posted by mohammad 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

May 2, 2012, 04:47
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 Originally Posted by truffaldino 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 ??

 May 2, 2012, 05:27 #4 Senior Member     Join Date: Jan 2011 Posts: 249 Blog Entries: 5 Rep Power: 17 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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