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April 22, 2013, 04:21 |
reduce 3D to 2D mesh
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#1 |
Member
Join Date: Feb 2013
Posts: 30
Rep Power: 13 |
Hi everybody,
I have a rather strange problem, namely, I have a 3D geometry but I want to perform a 2D simulation based on it. It would be a start if I could use the setSet or a similar utility to extract only my boundary faces (at one side) and use that as my 2D mesh, but I really don't know how to start - has anyone done this before? Or is there another way to get a 2D geometry? Thanks a lot, Natalie |
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April 22, 2013, 05:48 |
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#2 |
Member
Andreas Wendy
Join Date: Aug 2012
Posts: 73
Rep Power: 13 |
how do you create your mesh before. in snappyhexmesh you can for example also create a 2d mesh when the front and back faces are empty and nly 1 cell in the depth.
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April 22, 2013, 06:27 |
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#3 |
Member
Join Date: Feb 2013
Posts: 30
Rep Power: 13 |
Hi!
I export my mesh from Altair Hypermesh. It provides the possibility to export geometry in an OF format, but, as far as I know, for this option I need a tetrahedral volume mesh. SnappyHexMesh exports also a 2D geometry to every 3D geometry it creates? Maybe I should write to the Hypermesh support and ask whether this option is also available in Hypermesh. Kind regards, Natalie |
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April 22, 2013, 07:06 |
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#4 |
Member
Andreas Wendy
Join Date: Aug 2012
Posts: 73
Rep Power: 13 |
if you want to run a 2d simulation and want you use snappyhexmesh for meshing. you only have to be sure that your patches are defined the right way. so you can run snappy hexmesh and get no refinement in the third dimensiobns. what does your mesh in your third dimension looks like? if you only have 1 element you should run a 2d simulation by setting the front and back face to "empty"
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April 22, 2013, 15:01 |
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#5 |
Senior Member
Niels Gjoel Jacobsen
Join Date: Mar 2009
Location: Copenhagen, Denmark
Posts: 1,900
Rep Power: 37 |
Hi Natalie,
Potentially, you could use the utility "extrudeMesh", which are located in Code:
<OpenFOAM>/applications/utilities/mesh/generation/extrudeMesh Code:
Extrude mesh from existing patch (by default outwards facing normals; optional flips faces) or from patch read from file. Note: Merges close points so be careful. Type of extrusion prescribed by run-time selectable model. Niels |
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April 23, 2013, 04:16 |
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#6 |
Member
Join Date: Feb 2013
Posts: 30
Rep Power: 13 |
Actually, I have only 1 element in the third direction and I've tried just setting the front and back face to empty.. seems I got it wrong somehow, I will have a look at the tutorials.
@A Wendy: Can I import my 3D geometry into snappyHexMesh and get somehow a 2D mesh by extracting patches? Or what do you mean? Thanks a lot, Natalie |
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April 23, 2013, 06:08 |
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#7 | |
Member
Andreas Wendy
Join Date: Aug 2012
Posts: 73
Rep Power: 13 |
Quote:
you can have a look a at this example I created http://ubuntuone.com/722FQ4i7HA8A6KVDsVbYs4 best wishes Andy |
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May 2, 2013, 02:37 |
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#8 |
Member
Join Date: Feb 2013
Posts: 30
Rep Power: 13 |
Hi!
I'm afraid my browser does not find the homepage you posted a link to .. could you copy the example somehow into this forum? Thanks, Natalie |
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May 2, 2013, 03:37 |
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#9 | |
Member
Andreas Wendy
Join Date: Aug 2012
Posts: 73
Rep Power: 13 |
Quote:
i cleaned up my webspace. here is the new link http://ubuntuone.com/3kPBj7ob4yfD8bcHMzZyFK Andy |
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October 20, 2020, 09:53 |
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#10 | |
New Member
aglios 900
Join Date: Oct 2020
Posts: 1
Rep Power: 0 |
Quote:
my browser does not find the link you posted .. could you repost it please? aglios |
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December 11, 2020, 12:25 |
Mesh quality issues after using extrudeMesh
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#11 |
New Member
Benjamin Norris
Join Date: Oct 2020
Location: California
Posts: 17
Rep Power: 5 |
Hi everyone,
I am having some difficulties with the extrudeMesh utility and was wondering if anyone could give me some assistance. I have generated a 3D mesh around an STL file with snappyHexMesh. After meshing completes, I run checkMesh and the utility reports "Mesh OK". I then run extrudeMesh and createPatch to generate a 2D mesh from one of the 3D mesh walls. When I run checkMesh on this result, I get several skewFace errors. I gather from reading other forum posts that extrudeMesh might combine nearby points, thereby creating very thin cells (particularly near the STL surface). I have tried using the mergeTol = 0 setting in the extrudeMeshDict, to no avail. I have also tried setting the writeFormat in controlDict to "binary" as recommended in other forum posts, but this has not helped my specific case either. I have attached the relevant dict files here, including the checkMesh logs for the 3D and 2D cases. Any help resolving this issue would be greatly appreciated. Thanks, Ben |
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December 15, 2020, 12:15 |
Solved: Mesh quality issues after using extrudeMesh
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#12 |
New Member
Benjamin Norris
Join Date: Oct 2020
Location: California
Posts: 17
Rep Power: 5 |
Hi everyone,
I thought I would post an update to my last post about extrudeMesh creating mesh quality issues. I have been playing around with some different blockMesh and snappyHexMesh settings, and seem to have stumbled on something that works. I had set up my blockMeshDict to have 0.25 m^3 cells initially. The mesh was 68 m x 0.25 m x 4 m, e.g., Code:
scale 1; vertices ( ( 19 23 -3 ) // 0 ( 87 23 -3 ) // 1 ( 87 23.25 -3 ) // 2 ( 19 23.25 -3 ) // 3 ( 19 23 1 ) // 4 ( 87 23 1 ) // 5 ( 87 23.25 1 ) // 6 ( 19 23.25 1 ) // 7 ); blocks ( hex (0 1 2 3 4 5 6 7) (272 1 16) simpleGrading (1 1 1) ); The solution for me was to simply increase the number of cells in x-coordinate of the blockMeshDict by a small amount, e.g., Code:
hex (0 1 2 3 4 5 6 7) (280 1 16) simpleGrading (1 1 1) Hopefully this will help anyone who is having similar issues. I did not find that increasing the writePrecision or changing the writeFormat from ascii to binary, helped at all in my case. |
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