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-   -   Is it possible to have a mesh to represent a domain with a hole (http://www.cfd-online.com/Forums/openfoam-meshing-blockmesh/61853-possible-have-mesh-represent-domain-hole.html)

kmurphy May 3, 2006 05:09

Hi, (I had originaly posted
 
Hi,

(I had originaly posted this message in Meshing / Mesh conversion: gmsh sub group in error, sorry)

I am trying to construct a mesh to represent a rectangular region with a single circular hole. I started with the mesh used in tutorials/potentalFoam/cylinder (which matches half of my required mesh) and tried to extend this. When I do not split the blocks, i.e., using

hex (# # # # # # # #) (1 1 1) simpleGrading(1 1 1)

for each block, everything seems OK. Program checkBlock does not generate any warnings and the resulting mesh looks like http://www.cfd-online.com/OpenFOAM_D...ges/1/2287.png.

The output from checkMesh is in http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif checkMesh_2.log and the blockMeshDict file is http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict_1 .

Adding grading to most of the blocks works as I would have expected, to produce the following mesh http://www.cfd-online.com/OpenFOAM_D...ges/1/2290.png.

The output from checkMesh is in http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif checkMesh_2.log and
the blockMeshDict file is http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict_2 and everything appears OK.

However, when I try to add grading to any of the other blocks I do not obtain the expected (to me) mesh. In the following diagram and files I have only
added grading to two of the problem blocks to keep the mesh as simple as possible and the problem seem to be independent of the grading used in the other blocks.

http://www.cfd-online.com/OpenFOAM_D...ges/1/2293.png.

The output from checkMesh is http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif checkMesh_3.log and the blockMeshDict file is http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict_3 .

In the log of checkMesh there were reports of

High aspect ratio for cell 10: 4.44057e+199
High aspect ratio for cell 11: 4.44058e+199

and

Severe non-orthogonality detected for face ...

which doesn't appear to be too healthy.

I have tried to switch the order of the vertices without success. Any advice would be great,

Thanks, Kieran

hjasak May 3, 2006 05:24

Looks like you've messed up th
 
Looks like you've messed up the mesh definition - this kind of mesh should be pretty easy to do. As an encouragement, have one of mine :-) This is a mesh for vertex shedding behind a cylinder.

From the pictures it seems to me that the grading is giving you trouble: remember, the grading coefficients are defined in the coordinate system of the block and not the global one.

Good luck,

Hrv

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict

kmurphy May 3, 2006 17:10

Hi Hrvoje, Thanks for your bl
 
Hi Hrvoje,
Thanks for your blockMeshDict. I should able to use it to reconstruct mine (without the error this time). Regards, Kieran.

cesarjets October 13, 2014 17:23

Quote:

Originally Posted by hjasak (Post 186611)
Looks like you've messed up the mesh definition - this kind of mesh should be pretty easy to do. As an encouragement, have one of mine :-) This is a mesh for vertex shedding behind a cylinder.

From the pictures it seems to me that the grading is giving you trouble: remember, the grading coefficients are defined in the coordinate system of the block and not the global one.

Good luck,

Hrv

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict


could you share the whole file of this case? I mean I would like to check how you set up the U/P files?
thanks


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