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orthogonality in gambit

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Old   June 10, 2006, 03:33
Default orthogonality in gambit
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kohi
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Hi all,

How to generate orthogonal mesh in boundaries using the gambit software.

thank all.
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Old   May 13, 2009, 14:03
Default I also want to know
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Ivan
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I am trying to generate orthogonal mesh around an airfoil using GAMBIT. After a lot of attempts and search online, I am almost convinced that Gambit cannot do it.

I will be glad if anyone can confirm this or show how to do it.
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Old   May 13, 2009, 14:20
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Martin Gariepy
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I think youre right, Gambit can't do it. You will have to use ICEM CFD. You can try my little trick to mesh at 90 degrees, I'm using the boundary layer as a guide for the meshing, and the BL is always perpendicular to your wall. Hope it's help
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Old   May 14, 2009, 04:26
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Ralf Schmidt
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Hi!

Gambit ca create an orthogonal mesh... but it might be very tricky...

A BL mesh is NOT ALWAYS orthogonal to the surface!! If you have walls that are non orthogonal, and the BL is attached to these walls, the BL might align to these walls.

You can create an orthogonal mesh via premeshing the edges that are opposite to each other. In the mesh edges option, select both edges and mesh them together.

I grant, if you have an irregular shape inside your domain, a purely orthogonal mesh is impossible in gambit. BUT... how should this look like? I cannot imagine a purely orthogonal mesh on a curved surface.....

Best wishes
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Old   May 15, 2009, 18:40
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Thanks to Martin and Ralf, but I am a little confused.

To Martin, BL can not guarantee orthogonal mesh in the boundary layer. Unfortunately I do not have a license for ICEM CFD.

To Ralf, do you mean to LINK the two edges by "In the mesh edges option, select both edges and mesh them together.”

Some one told me GridGen by Pointwise Inc will do it, but I am not sure and I don't have a license.
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Old   May 16, 2009, 04:59
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Ralf Schmidt
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Hi!

yes, thats what i am talking about - select both parallel lines and select "soft link -> form" (this is standard setting).

Take care, that both lines are aligned in the same direction (the little red arrow shown)

You can post a picture of your geometry here. We can give you advice if and how to create an orthogonal mesh...

Best wishes
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Old   May 18, 2009, 17:03
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Thanks, Ralf,

I am not sure if linking the two edges (the upper edge and the lower edge of the airfoil) will help to generate orthogonal mesh around the airfoil. These two edges are not parallel, they are connected.

The geometry of the airfoil NACA4412 and the mesh I have right now is here

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Old   May 26, 2009, 00:17
Default Orthognality
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I think you make two contours.
1. Aerofoil
2. Offset aerofoil by a distance in which grid should remail orthognal.
make sure the offset distance is not very large.
the mesh inside this two curves will be nearly orthognal.
rest of the mesh between the outer boundary and offseted contour wont be orthognal
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