[ICEM] Problem with a C-Grid meshing technique for a wing

GodotMisogi · May 20, 2017, 03:12

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:

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.

May 20, 2017, 03:12	Problem with a C-Grid meshing technique for a wing	#1
GodotMisogi New Member Arjit Seth Join Date: Oct 2016 Posts: 1 Rep Power: 0	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: 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?

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May 22, 2017, 03:50		#2
Kirill_Makarov New Member Kirill Makarov Join Date: Feb 2017 Posts: 11 Rep Power: 9	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.