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-   -   [ICEM] Problem with a C-Grid meshing technique for a wing (https://www.cfd-online.com/Forums/ansys-meshing/188005-problem-c-grid-meshing-technique-wing.html)

 GodotMisogi May 20, 2017 03:12

Problem with a C-Grid meshing technique for a wing

Hello, this is my first post on these forums. I'm a newbie to CFD analysis, so please guide me by pointing out any mistakes you observe in my posts.

I've been playing around with 2D ICEM CFD meshes around airfoils with some success, but haven't been able to implement a 3D mesh around a wing with successful results.

The following analysis investigates the performance of a rectangular wing with an SG6042 at a low Reynolds number of 300,000 using ANSYS Fluent. The meshing strategy I came up with was based on a C-grid technique I learnt in 2D analyses, whose logic I extrapolated into 3D. The video I used to learn the C-grid implementation in 2D is:

http://i.imgur.com/SUi6H1d.jpg
http://i.imgur.com/Xu9Gez2.jpg
http://i.imgur.com/vvyEUJ4.jpg
http://i.imgur.com/YcHzIZc.jpg

The problem, I believe, lies somewhere in the meshing setup. The CFD results show the coefficient of lift values oscillating in the thousands (sometimes peaking in the millions). Pausing the solution and checking the velocities in CFD-Post shows that the front of the exposed wingtip has air which reaches velocities of Mach 2, which is obviously impossible.

Any ideas on what the issues could be?

 Kirill_Makarov May 22, 2017 03:50

Unfortunately you did not describe what was exactly the problem with your mesh. At first sight you can improve your mesh in two ways. First of all, it seem like you use default amount of aspect ratio of 2. Try to reduse it up to 1.2 or 1.1. Second issue is that you have huge difference in cell lenght on trailing edge. Try to smooth it.

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