[Other] Problems with mesh processing

STutexas · November 14, 2015, 20:36

Hi

I am trying to convert a stacked CT images to Openfoam mesh. I use the matlab (Iso2mesh) to process the images and generate the mesh in the stacked images. Then I save it as a gmsh file. The problem that I have is that the mesh generated does not seem to have a separate boundary settings. So Openfoam (or any other software like gmsh) is not able to read my mesh file. Please let me know if there is a fix for this problem. I am open to other suggestions about mesh processing in CT images as well.

Thank you.

cutter · November 16, 2015, 07:40

Hi,

depending on the complexity of your geometry and the resulting iso surface either autoPatch (create Patches by splitting along feature edged) or a combination of topoSet/setSet (selection of a set of faces boxes etc.) together with createPatch (create a patch from the face set) might be a viable option.

Please have a look at the tutorial cases and the header files of the tools' source code for some sample dictionaries for these tools.

Cutter

STutexas · November 17, 2015, 18:34

Hi

Thank you for the help. I will peruse the createPatch command
This is the format of my .msh file that I upload into Openfoam.

$MeshFormat
2.2 0 8
$EndMeshFormat

$PhysicalNames
1
3 1 "region_1"
$EndPhysicalNames

$Nodes

226574

..List of nodes

$EndNodes

$Elements

433391

..List of Elements

$End of Elements

When I use gmshToFoam I get the following error. Please help me understand this error.

Create time
#0 Foam::error:

rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigSegv::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::PtrList<Foam:

olyPatch>:

perator[](int) const at ??:?
#4 ? at ??:?
#5 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#6 ? at ??:?
Segmentation fault (core dumped)
saurabh@saurabh-VirtualBox:~/OpenFOAM/saurabh-2.4.0/run/tutorials/basic/import_check$

STutexas · November 23, 2015, 00:56

I have sorted the problem of using gmsh by modifying the code that created teh gmsh file. But I am having trouble controlling the quality of the mesh that I generated. Are there any tools in OpenFOAM that can help me improve mesh quality or would I have to do that before I upload the mesh.

Thanks again for the help.

Saurabh

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November 14, 2015, 20:36	Problems with mesh processing	#1
STutexas Member Saurabh Tandon Join Date: Nov 2015 Location: Austin Posts: 43 Rep Power: 10	Hi I am trying to convert a stacked CT images to Openfoam mesh. I use the matlab (Iso2mesh) to process the images and generate the mesh in the stacked images. Then I save it as a gmsh file. The problem that I have is that the mesh generated does not seem to have a separate boundary settings. So Openfoam (or any other software like gmsh) is not able to read my mesh file. Please let me know if there is a fix for this problem. I am open to other suggestions about mesh processing in CT images as well. Thank you.

November 16, 2015, 07:40		#2
cutter Senior Member Join Date: Mar 2010 Location: Germany Posts: 154 Rep Power: 16	Hi, depending on the complexity of your geometry and the resulting iso surface either autoPatch (create Patches by splitting along feature edged) or a combination of topoSet/setSet (selection of a set of faces boxes etc.) together with createPatch (create a patch from the face set) might be a viable option. Please have a look at the tutorial cases and the header files of the tools' source code for some sample dictionaries for these tools. Cutter

November 17, 2015, 18:34		#3
STutexas Member Saurabh Tandon Join Date: Nov 2015 Location: Austin Posts: 43 Rep Power: 10	Hi Thank you for the help. I will peruse the createPatch command This is the format of my .msh file that I upload into Openfoam. $MeshFormat 2.2 0 8 $EndMeshFormat $PhysicalNames 1 3 1 "region_1" $EndPhysicalNames $Nodes 226574 ..List of nodes $EndNodes $Elements 433391 ..List of Elements $End of Elements When I use gmshToFoam I get the following error. Please help me understand this error. Create time #0 Foam::error:rintStack(Foam::Ostream&) at ??:? #1 Foam::sigSegv::sigHandler(int) at ??:? #2 ? in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::PtrList<Foam:olyPatch>:perator[](int) const at ??:? #4 ? at ??:? #5 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #6 ? at ??:? Segmentation fault (core dumped) saurabh@saurabh-VirtualBox:~/OpenFOAM/saurabh-2.4.0/run/tutorials/basic/import_check$

November 23, 2015, 00:56		#4
STutexas Member Saurabh Tandon Join Date: Nov 2015 Location: Austin Posts: 43 Rep Power: 10	I have sorted the problem of using gmsh by modifying the code that created teh gmsh file. But I am having trouble controlling the quality of the mesh that I generated. Are there any tools in OpenFOAM that can help me improve mesh quality or would I have to do that before I upload the mesh. Thanks again for the help. Saurabh