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[snappyHexMesh] Base mesh is not removed completely |
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June 16, 2017, 09:11 |
Base mesh is not removed completely
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#1 |
New Member
DANG
Join Date: Apr 2016
Location: Lyon 1, France
Posts: 26
Rep Power: 10 |
Hi Guys,
I am trying to use snappyhexmesh utility to generate mesh for a CSTR. I found a kind of annoying thing: When I set base meshing below in the blockMeshdict, the snappyhexmesh utility works well: blocks ( hex (0 1 2 3 4 5 6 7) ( 64 75 65) simpleGrading (1 1 1) ); But when I wanted to increase the base mesh density like below, the snappy fails to remove the base mesh completely (see the pic in the attached case file). blocks ( hex (0 1 2 3 4 5 6 7) (84 95 88) simpleGrading (1 1 1) ); I have uploaded the case file to the link: https://www.dropbox.com/s/dxn5lhlug8go0mt/help.zip?dl=0 Hope you guys could take a look, and see if you have some tips!! Many thanks! Best regards, |
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June 16, 2017, 15:12 |
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#2 |
Senior Member
Lasse Brams Vinther
Join Date: Oct 2015
Posts: 112
Rep Power: 10 |
Hello Dang,
I briefly tested your case with both blockMesh specifications and I was wondering what patch the issuing cells are stored in for for the paraview figure? I initially assumed that they were stored in allBoundary patch, however, this patch exist for both blockMesh specifications when I run the Allrun.pre script, being inconsistent with your initial issue. I'll look further into it in the next week as I'm quite busy the next three days. |
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June 16, 2017, 16:09 |
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#3 | |
New Member
DANG
Join Date: Apr 2016
Location: Lyon 1, France
Posts: 26
Rep Power: 10 |
Hi Swagga5aur,
Thanks for your response. I re-run it again, the problem could be reproduced. You just need to run the Allrun.pre script, after it is done you will find the allBoundary patch still exists in the final mesh. Normally the allBoundary patch should be gone after the final mesh is obtained. Hope I have made my problem clear to you. Best regards, Quote:
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June 20, 2017, 08:02 |
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#4 |
Senior Member
Lasse Brams Vinther
Join Date: Oct 2015
Posts: 112
Rep Power: 10 |
Hello again DANG,
I just ran the two blockMeshes resulting in the following two figures with a remaining background mesh in both so I am wondering what openFOAM version you are using, I am using 4.1. I'll try lower background mesh densities to try and pinpoint when the issue occurs. Left figure is the blockMesh of (64 75 65) and the right is the (84 95 88). |
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June 20, 2017, 08:15 |
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#5 | |
New Member
DANG
Join Date: Apr 2016
Location: Lyon 1, France
Posts: 26
Rep Power: 10 |
Hi Swagga5aur,
I use version 4.0, it is interesting problem, I still get no answer to this. Let's see if you can get more information... Best regards, Quote:
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June 20, 2017, 10:12 |
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#6 |
Senior Member
Lasse Brams Vinther
Join Date: Oct 2015
Posts: 112
Rep Power: 10 |
Hello again,
I believe the issue lies in the stl files that you use as misalignment is observed of the surface triangulations as well as unenclosed surfaces. This is probably the cause to this unremoved backgroundmesh as the cells aren't part of the domain and can't be snapped to a nonexisting connecting surface. This is shown in the below figure where a gap is noticed as well as misaligned vertices. This has already been discussed how to solve in posts such as https://www.cfd-online.com/Forums/op...pyhexmesh.html and https://www.cfd-online.com/Forums/op...sh-salome.html Hope its of some help, let me know if you have any questions. |
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June 21, 2017, 11:14 |
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#7 | |
New Member
DANG
Join Date: Apr 2016
Location: Lyon 1, France
Posts: 26
Rep Power: 10 |
Hello Swagga5aur,
After increasing the quality of the stl file, the problem is solved. Thank you very much for your information. Best regards, Quote:
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