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September 15, 2008, 00:30 |
Hrv,
Something came to mind
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#41 |
Senior Member
Chris Sideroff
Join Date: Mar 2009
Location: Ottawa, ON, CAN
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Hrv,
Something came to mind after I posted. If the triangular surface meshing is done independently from the tetrahedral volume meshing, the tet mesh may not be able to modify to surface mesh to allow the tets near the surfaces to be Delaunay - I believe this is called 'constrained Delaunay' meshing. Constrained Delaunay meshes may not be strictly Delaunay. This a common approach for most mesh generators as the user typically 'tunes' the surface mesh manually - through local refinement and boundary point adjustment - and the volume mesh is generated based off the surface mesh. This may be where the loosening of the Delaunay criteria may be appearing. Chris |
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July 9, 2009, 06:31 |
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#42 |
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Björn Fabritius
Join Date: Mar 2009
Location: Freiberg, Germany
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It seems like polyDualMesh still suffers from some restrictions. Unfortunately in the current state it's of not much use to me.
Do you know of any papers on the matter? I would like to know more about what the polyDualMesh tool actually does. I tried to understand all of it by browsing the code, but that is at least tedious work. The common search engines did not yield any useful links when searching for something like "convert tetrahedral to polyhedral grids". (80% of the links point to this forum...) Bjoern |
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July 10, 2009, 03:41 |
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#43 | |
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Mark Olesen
Join Date: Mar 2009
Location: https://olesenm.github.io/
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Quote:
http://www.anova.com.tr/dosyalar/destek/polyhedral.pdf You might also try searching for < voronoi delaunay > - this is a somewhat similar concept. |
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November 10, 2010, 10:10 |
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#45 |
Senior Member
Markus Rehm
Join Date: Mar 2009
Location: Erlangen (Germany)
Posts: 184
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Hello,
I converted a hybrid mesh with polyDualMesh and got nice poly cells in the former tet region but in the hexa region the cells are split leading to a huge final mesh. I suppose that polyDualMesh splits one hexa cell into 8 new hexas. Is there a way to supress this behaviour or to apply the utility only in a certain region? Regards Markus. |
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November 10, 2010, 10:40 |
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#46 | |
Senior Member
Mark Olesen
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Quote:
If I check with the mesh from angledDuctImplicit, then checkMesh reports Before: hexahedra: 22000 After: hexahedra: 23232 prisms: 4 polyhedra: 1460 The non-hexas arise from the corners of the domain. At least for this type of mesh I wouldn't say that the increase in the cell count is excessive. |
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November 11, 2010, 05:06 |
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#47 |
Senior Member
Markus Rehm
Join Date: Mar 2009
Location: Erlangen (Germany)
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Hello Mark,
thank you for your reply. I can confirm your observation for the angledDuct geometry. I ran another test with the cavity case and the cell number goes up from 400 to 882. In our geometry which has quite a few edges I start with 0.4 mill. cells and end up with 2.7 mill. ! I post some pictures of the two examples. Do you see a chance to ignore the hexas in the polyDualMesh algorithm? As it works now it is not very benefitial for complex hybrid geometries. Regards, Markus |
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November 11, 2010, 05:40 |
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#48 | ||
Senior Member
Mark Olesen
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Quote:
Quote:
1. Identify the hex-dominant region that you don't want dualized and assign it to a cellset. This region should be contiguous. 2. Use splitMeshRegions to split things apart. 3. You'll need a modified polyDualMesh that handles the '-region' option so that you only dualize a particular region. You might need support help for that. 4. Rejoin the mesh regions. I don't find a command for that immediately, but it must be there (I hope). |
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November 11, 2010, 06:01 |
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#49 |
Senior Member
Markus Rehm
Join Date: Mar 2009
Location: Erlangen (Germany)
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Thanks a lot. I will check it out.
Markus |
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July 17, 2012, 03:59 |
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#50 |
Super Moderator
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
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Hello,
Did you solved your problem? I tried yesterday to convert a 4 millions cells with polyDualMesh and it generated 21 millions cells. My mesh comes from Gambit, and it is an hybrid one : Hexa Volumes in combination with Volumes which are meshed with tetra-hexcore schema. With this schema a core of hexa is generated within the volume, and surrounding it there are some tetra layers. I would like to convert only tetra in polyhedra any idea?
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In memory of my friend Hervé: CFD engineer & freerider |
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