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-   -   [ANSYS Meshing] Meshing around sharp trailing edge in CFX (https://www.cfd-online.com/Forums/ansys-meshing/126095-meshing-around-sharp-trailing-edge-cfx.html)

 ttu004 November 8, 2013 00:11

Meshing around sharp trailing edge in CFX

1 Attachment(s)
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

 siw November 8, 2013 03:21

You may want to increase the maximum angle to 180 (the default is 140). This is found in the global inflation details by setting the advanced option to ON.

What have you done to cause the inflation layer to only really build up on the leading half of the aerofoil? It looks like the stair stepping collison adoidance is being used. Perhaps fixing that will more likely help with the inflation layers around the trailing edge. Also you may want to increase the cell density at the trailing edge.

Are you using the Pre-Inflation or Post-Inflation method?

 ttu004 November 8, 2013 03:54

Hi Stuart

It was really helpful!! As I turn 140 to 180 the inflation resolve the entire edges!!

By the way, I am only using inflation with First layer thickness method and I did not use stair stepping collison adoidance for sure.

Also, I am using pre-inflation for this analysis.

Cheers
Tom

 marcel_jay May 30, 2016 08:16

Maximum Angle confusion

I have some highley skewed elements near sharp edges (about 120°) and I don't know how to improve the inflation layers. Chaging the maximum angle (anything between 90 and 180°) did not change the mesh. It had to be refreshed but it stays exactly the same.

Any idea? Or maybe it's because I don't even understand the definition of it...

Code:

`The Maximum Angle control determines prism layer growth around angles, and when prisms will adhere (project) to adjacent surfaces/walls. If the inflated mesh involves extruding from one surface and not its neighbor, and the angle between the two surfaces is less than the specified value, the prisms (sides) will adhere (project) to the adjacent wall.`
Cheers

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