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-   -   [cfMesh] CfMesh Stop Layer growth at symmetryPlane (https://www.cfd-online.com/Forums/openfoam-community-contributions/153305-cfmesh-stop-layer-growth-symmetryplane.html)

jojosaxo May 22, 2015 06:48

CfMesh Stop Layer growth at symmetryPlane
 
1 Attachment(s)
Dear All,
I'm trying to mesh a ship hull with cfMesh. I tried to use snappyHexMesh but cfMesh seems to gives much better result when it comes to layer addition. My main issue was to get continious layers around corners. cfMesh seems to do that very well!
However, I'm only modeling a half-hull, but I don't want to have layers on the symmetry-plane. How can i have no layer on the symmetry plane without having some kind of triangular cells at the corner (see attached pictures)!

Many Thanks for your help!

franjo_j May 26, 2015 06:59

Hello,

cartesianMesh generates at least on layer everywhere at the boundary, see generateBoundaryLayers function in cartesianMeshGenerator.C.
I suggest that you try tetMesh first and find out whether you get the topology you want. It only creates layers at specified locations. If that works for you, then you can copy the content of generateBoundaryLayers function in tetMeshGenerator.C and use it in cartesianMeshGenerator.C. However, this may come with a price of reduced mesh quality.
I hope this helps!

jojosaxo May 26, 2015 07:56

Thank you for your answer!
Unfortunately I can't use tetMesh since I absolutely need a high aspect ratio cells close to the free surface. By the way thanks to the anisotropic refinement tool you've set up I can create such kind of refinement.
About BL, I think I'll have to deal with that.

However about free surface refinement, I would like to have a continious layer at the free surface with high aspect ratio. Ideally the thickness (z size) of any cell at the far field should be the same as the thickness close to the hull (where x and y size are much smaller). Does anyone have any clue about that???

massimiliano.tarrini November 6, 2020 03:16

Quote:

Originally Posted by franjo_j (Post 547681)
Hello,

cartesianMesh generates at least on layer everywhere at the boundary, see generateBoundaryLayers function in cartesianMeshGenerator.C.
I suggest that you try tetMesh first and find out whether you get the topology you want. It only creates layers at specified locations. If that works for you, then you can copy the content of generateBoundaryLayers function in tetMeshGenerator.C and use it in cartesianMeshGenerator.C. However, this may come with a price of reduced mesh quality.
I hope this helps!

is it then necessary to recompile?

massimiliano.tarrini November 6, 2020 04:27

Quote:

Originally Posted by jojosaxo (Post 547305)
Dear All,
I'm trying to mesh a ship hull with cfMesh. I tried to use snappyHexMesh but cfMesh seems to gives much better result when it comes to layer addition. My main issue was to get continious layers around corners. cfMesh seems to do that very well!
However, I'm only modeling a half-hull, but I don't want to have layers on the symmetry-plane. How can i have no layer on the symmetry plane without having some kind of triangular cells at the corner (see attached pictures)!

Many Thanks for your help!

Hi! I am facing the same problem. BL spreads out to the mirror plane.
I tried to use by comparison ASMOctree adding layers and you know what is funny?
the BL is nicely mapped on thebody and it ends normal to the mirror plane... did you manage to solve?
regs
max


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