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[snappyHexMesh] SnappyHexMesh with .stl-geometry |
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November 16, 2018, 08:05 |
SnappyHexMesh with .stl-geometry
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#1 |
Member
Stefanie Wolf
Join Date: Nov 2018
Location: Aachen
Posts: 32
Rep Power: 7 |
Hello,
i would like to use snappyHexMesh with an stl-file from Solid Works. My BlockMesh is large enough for my geometry and should be fine enough to catch all lines of my geometry. Still snappyHexMesh gets stuck and does not continue with the process. I do not run the process parallel.
Why does it not work? Reading surfaceFeatureExtractDict Surface : "WandEinlauf.stl" Feature line extraction is only valid on closed manifold surfaces. #0 Foam::error:rintStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigSegv::sigHandler(int) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 ? in "/lib64/libc.so.6" #3 yyFlexLexer::yy_get_previous_state() in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #4 STLLexer::lex() in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #5 Foam::triSurface::readSTLASCII(Foam::fileName const&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #6 Foam::triSurface::readSTL(Foam::fileName const&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #7 Foam::triSurface::read(Foam::fileName const&, Foam::word const&, bool) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #8 Foam::triSurface::triSurface(Foam::fileName const&) in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/lib/libtriSurface.so" #9 ? in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/bin/surfaceFeatureExtract" #10 __libc_start_main in "/lib64/libc.so.6" #11 ? in "/opt/OpenFOAM/OpenFOAM-2.4.0/platforms/linux64GccDPOpt/bin/surfaceFeatureExtract" Segmentation fault (core dumped) Last edited by Stefanie.S.W.; November 16, 2018 at 08:11. Reason: 1st post, problems with editor |
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November 16, 2018, 08:45 |
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#2 |
Member
ssa
Join Date: Sep 2018
Posts: 93
Rep Power: 7 |
try saving the stl as ascii version and run surfacefeatureExtract.. then run snappy.
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November 19, 2018, 03:20 |
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#3 | |
Senior Member
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
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Quote:
Code:
snapControls { ... // Feature snapping ... //- Detect (geometric) features by sampling the surface implicitFeatureSnap true; //- Use castellatedMeshControls::features explicitFeatureSnap false; //- Detect features between multiple surfaces // (only for explicitFeatureSnap, default = false) multiRegionFeatureSnap true; }
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November 19, 2018, 04:18 |
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#4 |
Member
Stefanie Wolf
Join Date: Nov 2018
Location: Aachen
Posts: 32
Rep Power: 7 |
Thank you a lot for helping and explaining ssa_cfd and RobertHB!
I feel like understanding the dictionary a little bit more now. My first mistake was that my geometry was a lot larger than I thought, because OpenFoam writes every length in [m]. Unfortunately SHM does not return an error message in this case. Maybe it just kept on trying to snap the block mesh to a 1000 times larger object. I saved the geometry as .stl in ASCII and converted mm to m. Now it works :-) |
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November 19, 2018, 04:29 |
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#5 | |
Senior Member
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 11 |
Quote:
As for your .stl not matching your blockMesh, you can always open your blockMesh in paraview and load the .stl to see if the two overlap.
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November 21, 2018, 10:17 |
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#6 | |
Member
Stefanie Wolf
Join Date: Nov 2018
Location: Aachen
Posts: 32
Rep Power: 7 |
thanks to your help I could reduce the no of incorrectly orientated face pyramids to 10 and the no of highly skew faces to 2 - still I think those errors hinder the computation.
Additionally I could fix the incorrectly orientated face pyramids by using higher refinement in SnappyHexMesh and using "xxx.eMesh" for the features sub dictionary. Now a new error occurred (besides the two skew faces): the bottom wedge remained after increasing the refinement. Before SnappyHexMesh removed the wedge. I hope you can see it on the picture attached Is there a way to remove the wedge without changing the blockMesh to a sloped geometry? Also do you know which parameter can help with fixing the skew faces? Is it a parameter in the snappyHexMeshDict? I attached the dict below. Thank you for your help! Hopefully the quotation of the Mesh-Quality-Code works..... Quote:
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November 22, 2018, 03:36 |
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#7 | ||
Senior Member
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 11 |
Quote:
1) You are using multiple .stl files to construct one geometry. In this case sHM might struggle combining the parts into one and thus also includes the blockMesh. 2) You are using one geometry, which you are trying to mesh from the inside. sHM not discarding the outer blockMesh can be a sign of your geometry not being closed or "watertight". sHM uses all cells it can "see" from the pointInMesh. If you have a hole in your mesh, sHM can see the outer cells and thus includes the outside aswell. Quote:
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