[mesh manipulation] Generating a single cell mesh using a patch of a 3d mesh

kebsiali · May 26, 2016, 11:47

Hello dear foamers

I'm trying to generate a single cell mesh(one cell in the 3rd dimension) using a patch of a 3d mesh.

The idea is that i need to run a pre-curser simulation on the 2d mesh by applying a periodic boundary mesh, and then use the result to generate my inlet fields given as nonuniform list of values.

my mesh is generated using HEXPRESS, exported in openfoam format
so i have all the files (points, cells, owner, neighbor, boundary)

Is there a utility that extracts one the patches and generate a 2d mesh (with one cell in 3rd dimension) out of it.

Otherwise what do you think i should do?
my idea is to:
1. sample the patch
2. make a fortran function that reads the coordinates
3. write out a list of couples of points having same 2 coords and uncoupled in the 3rd (to make the two sides of my one cell)
4. the problem will now be to write out all other crazy lists (cells, owner, neighbor,boundary)

any ideas are wellcom

Antimony · May 26, 2016, 22:18

Hi,

Would extrudeMesh work for you? https://github.com/OpenFOAM/OpenFOAM...xtrudeMeshDict

You can set the nLayers to 1 and choose the direction you want to extrude in and get your mesh, I would think. No?

Cheers,
Antimony

kebsiali · May 30, 2016, 06:38

Hi,

Thanks for your quick reply. It took me a bit of time to try. but i dont see how extrudeMesh would remove a full 3dmesh and generate a seperate mesh by extruding a patch.

Is there a tool that eliminates a part of the geometry such that i can keep a small part close to my patch.
Is there a way to force extrudeMesh to remove 3d mesh and keep only the extrusion from a 2d patch.

thanks,
Ali

Antimony · May 30, 2016, 07:36

Hi,

You don't need to remove the full 3d mesh. Instead you can create a dummy case, and specify in the extrudeMeshDict that it has to source from the full 3d mesh case.

For eliminating parts of the mesh, you might want to look at subsetMesh or splitMesh/splitMeshRegions depending on your requirement.

Hope this helps.

Cheers,
Antimony

May 26, 2016, 11:47	Generating a single cell mesh using a patch of a 3d mesh	#1
kebsiali Member ali alkebsi Join Date: Jan 2012 Location: Strasbourg, France Posts: 82 Rep Power: 14	Hello dear foamers I'm trying to generate a single cell mesh(one cell in the 3rd dimension) using a patch of a 3d mesh. The idea is that i need to run a pre-curser simulation on the 2d mesh by applying a periodic boundary mesh, and then use the result to generate my inlet fields given as nonuniform list of values. my mesh is generated using HEXPRESS, exported in openfoam format so i have all the files (points, cells, owner, neighbor, boundary) Is there a utility that extracts one the patches and generate a 2d mesh (with one cell in 3rd dimension) out of it. Otherwise what do you think i should do? my idea is to: 1. sample the patch 2. make a fortran function that reads the coordinates 3. write out a list of couples of points having same 2 coords and uncoupled in the 3rd (to make the two sides of my one cell) 4. the problem will now be to write out all other crazy lists (cells, owner, neighbor,boundary) any ideas are wellcom

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May 26, 2016, 22:18		#2
Antimony Senior Member Join Date: Aug 2013 Posts: 407 Rep Power: 16	Hi, Would extrudeMesh work for you? https://github.com/OpenFOAM/OpenFOAM...xtrudeMeshDict You can set the nLayers to 1 and choose the direction you want to extrude in and get your mesh, I would think. No? Cheers, Antimony

May 30, 2016, 06:38		#3
kebsiali Member ali alkebsi Join Date: Jan 2012 Location: Strasbourg, France Posts: 82 Rep Power: 14	Hi, Thanks for your quick reply. It took me a bit of time to try. but i dont see how extrudeMesh would remove a full 3dmesh and generate a seperate mesh by extruding a patch. Is there a tool that eliminates a part of the geometry such that i can keep a small part close to my patch. Is there a way to force extrudeMesh to remove 3d mesh and keep only the extrusion from a 2d patch. thanks, Ali

May 30, 2016, 07:36		#4
Antimony Senior Member Join Date: Aug 2013 Posts: 407 Rep Power: 16	Hi, You don't need to remove the full 3d mesh. Instead you can create a dummy case, and specify in the extrudeMeshDict that it has to source from the full 3d mesh case. For eliminating parts of the mesh, you might want to look at subsetMesh or splitMesh/splitMeshRegions depending on your requirement. Hope this helps. Cheers, Antimony