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ttu004 November 6, 2013 19:27

Meshing around sharp trailing edge in CFX
 
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Hi Guys

Could anyone tell me how to make the inflation around the sharp trailing edge of an airfoil without letting them skewed? (as shown in the figure below).

As my intention is to capture turbulent flow inside the near wall regions of an S814 airfoil, I have set the first cell height to 0.000014 m (y+ = 1) and the turbulent boundary layer thickness to 0.0116 m (using flat plate theory) by using the First layer thickness method. (maximum layers: 28, first layer height: 0.000014, growth rate: 1.2)

However, with this defined inflation control cells around the trailing edge (sharp tip) become highly skewed. And I believe that this is the reason that the computational results (lift/drag coefficients) are diverging from the experimental validation.

Thanks for any suggestions or advice
Tom

tcarrigan December 6, 2013 18:46

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Hello,

It's extremely challenging to create a boundary layer resolved mesh via inflation that nicely wraps around the highly convex trailing edge corner. However, some tools offer the ability to wrap around convex corners by splaying off multiple normals as the inflation wraps around the corner (see image, normals highlighted in blue).

For airfoils with sharp trailing edges, traditionally you'll see people use c-grids. The other photo is a zoomed-in image of the trailing edge of an airfoil with a c-grid style extrusion.

- Travis


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