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Old   August 23, 2007, 07:26
Default ICEM - mesh near wing trailing edge
  #1
Joao Lourenco
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Hello everyone!

I am new using ICEM and I've run into a few problems.

I am trying to make a volume mesh around an airplane and I'm having problems with the trailing edge of the wing. The mesh in that area is very bad. Please see the following link:

http://img72.imageshack.us/img72/722...ingedgewt4.png

I've tried many things to solve this: lowering the max deviation of the elements on those surfaces, placing iso-curves near the trailing edge of the wing to make sure that elements will be placed on the nodes of the curves. Nothing I've tried seems to be working.

I think it might be of the smoothing operations on the triangles when the surface mesh is generated. I've tried turning it off in the volume mesh settings but it still does this.

I really don't know what else to try. Can anyone please help me?

Thank you very much for your attention and I'm sorry for the rather big post.

Regards, Joao
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Old   August 23, 2007, 10:36
Default Re: ICEM - mesh near wing trailing edge
  #2
myron
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If this is a blunt trailing edge - e.g. with rounds - then you probably need to specify a smaller mesh size on the rounded surface(s) to better resolve it.

If it is a sharp trailing edge - you need to use 'thin cuts'. You place the pressure and suction surfaces in different parts - and the curve between them (the sharp edge) in yet a third part. Then you define a thin cut between the pressure and suction surfaces. This helps to keep the two surfaces separated - while still having a 'larger' mesh size.
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Old   August 23, 2007, 11:59
Default Re: ICEM - mesh near wing trailing edge
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Joao Lourenco
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Thank you. It a sharp trailing edge. I'm going to give it a try.

Regards, Joao
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Old   August 27, 2007, 06:35
Default Re: ICEM - mesh near wing trailing edge
  #4
Joao Lourenco
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I have defined two new parts in the sharp edge zone, one for the suction and the other for the pressure surface. I have also defined smaller elements there and even tried to use a low max deviation value. Even though the results were better the same problem persists (the elements from bottom and top surfaces start collapsing into each other). Please see picture in link below:

http://img260.imageshack.us/img260/4...ngedge2tr2.png

Any suggestions?

Thank you for your attention.

Best regards,

Joao

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Old   August 29, 2007, 11:08
Default Re: ICEM - mesh near wing trailing edge
  #5
myron
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I'm assuming you also have the curve at the sharp edge - in a part different from the 2 surfaces. If the angle is very small - i.e. a knife edge - then about the only way to fix it is via manual editing. That requires building surface elements via selecting nodes - and filling the volume elements behind it. You can also try using the surface mesher first - then fill the volume using Delauney or Advancing Front.

Sometimes larger elements actually work better on these knife edges - then you can refine those elements after the fact.
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Old   August 30, 2007, 17:20
Default Re: ICEM - mesh near wing trailing edge
  #6
Joao Lourenco
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I've tried using surface mesher first but the problem remains the same. I believe it's because in the end of the meshing run ICEM starts smoothing the triangles.

Is there any way to stop this?

Thanks for your help so far.

Best regards, Joao
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