ElmerGrid generating wrong geometry

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envog
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Joined: 21 Dec 2022, 20:11
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ElmerGrid generating wrong geometry

Post by envog »

Hi All

I am trying to define a 2-dimensional geometry in ElmerGrid as described in detail here http://cfd.mace.manchester.ac.uk/ercoft ... es:case010 and generate a computational mesh for Elmer. The commands I am using can be found in the attached file. The issue I am facing is that the bottom boundary is not flat but curved and it actually follows the curvature of the top boundary surface. I have tried to define the bottom surface using a linear interpolation between two points but it did not work out.
Do you have any suggestion?

Thanks
Evangelos
Attachments
CouetteFlowFixedWavyWall.grd
ElmerGrid input file
(684 Bytes) Downloaded 40 times
Rich_B
Posts: 421
Joined: 24 Aug 2009, 20:18

Re: ElmerGrid generating wrong geometry

Post by Rich_B »

Hello,

The Elmergrid manual includes an example of a sinusoidal mapping. The attached file is taken from the manual, with a slight modification to have a flat lower boundary. I haven't tried to modify the upper boundary, that is something that will take some work.

Rich.
tube-sine.png
tube-sine.png (79.98 KiB) Viewed 436 times
Attachments
tube-sine.grd
(738 Bytes) Downloaded 36 times
kevinarden
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Re: ElmerGrid generating wrong geometry

Post by kevinarden »

ElmerGrid for mesh definition is very confusing for me. It is a great translator, but with powerful easy to use mesh generators, like gmsh and Salome. I would never go to ElmerGrid to generate a mesh. Attached is a gmsh file to generate the mesh.
wall.geo
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gmsh.png
gmsh.png (20.12 KiB) Viewed 428 times
Rich_B
Posts: 421
Joined: 24 Aug 2009, 20:18

Re: ElmerGrid generating wrong geometry

Post by Rich_B »

I agree with Kevin, you are much better off using gmsh for your case.

Rich.
raback
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Re: ElmerGrid generating wrong geometry

Post by raback »

Hi, I also agree. Do not use ElmerGrid native format except for simple rectangular forms. Many tests favor ElmerGrid format since the tests are very simple usually and also the code always comes with Elmer installation. There are a few mapping possibilities to go from rectangular to curved but I think you should avoid those because of their obscurity. -Peter
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