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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Mesh Import Problem

Posted 24.04.2012, 09:03 GMT-4 Computational Fluid Dynamics (CFD), Geometry, Mesh Version 4.2a 4 Replies

StudentDK
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Hello everybody,

I have imported a nastran file (*.nas) but after the import i can't select any boundaries.
I have attached my project file that you can see my problem. For example i want to set up Boundary 3 as "Sliding Wall"!
Does anybody know a solution?

Thank you in advance!
4 Replies Last Post 27.08.2012, 08:16 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 24.04.2012, 15:19 GMT-4
Hi

your issue is tat COMSOL has not managed to translate your imported mesh into any geoemtry. COMSOL attaches physics to the geoemtry and then port this to the mesh by "inherance", while other programmes traditionally mesh the volume and then define the physics on the mesh elements and nodes.

When you import a mesh you need to get it reconstructed into a geoemtry with domains and boundaries, this does not always work. Did you import it as an explicit natran file ? Anyhow I'm not sure how well that was implemented in your v4.1, you might need a more up to date version. Anyhow the import mesh is rather difficult to do, I ave mostly given up that way ;)

--
Good luck
Ivar
Hi your issue is tat COMSOL has not managed to translate your imported mesh into any geoemtry. COMSOL attaches physics to the geoemtry and then port this to the mesh by "inherance", while other programmes traditionally mesh the volume and then define the physics on the mesh elements and nodes. When you import a mesh you need to get it reconstructed into a geoemtry with domains and boundaries, this does not always work. Did you import it as an explicit natran file ? Anyhow I'm not sure how well that was implemented in your v4.1, you might need a more up to date version. Anyhow the import mesh is rather difficult to do, I ave mostly given up that way ;) -- Good luck Ivar
StudentDK
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Posted: 1 decade ago 25.04.2012, 07:29 GMT-4
Hi,

yes it is an explicit nastran file.

I have an idea but i don't know if it's work:

I have the mesh statistics of the mesh i want to create. Can I make a new project with my own geometry and then set up the mesh options like in the mesh statistics?

I mean is it possible to generate a similiar mesh when I only have the data from the statistics?

If the answer is yes: How can I do this?

For example I want to have:

- 81484 Triangular Elements
- 547 Edge Elements
- 8 Vertex Elements

-81484 Number of Elements
-0.0975 Minimum Quality
-0.6851 Average Element Quality
-0.08705 Element area ratio
- 2.4 m^2 Mesh face area

Thank you in advance!
Hi, yes it is an explicit nastran file. I have an idea but i don't know if it's work: I have the mesh statistics of the mesh i want to create. Can I make a new project with my own geometry and then set up the mesh options like in the mesh statistics? I mean is it possible to generate a similiar mesh when I only have the data from the statistics? If the answer is yes: How can I do this? For example I want to have: - 81484 Triangular Elements - 547 Edge Elements - 8 Vertex Elements -81484 Number of Elements -0.0975 Minimum Quality -0.6851 Average Element Quality -0.08705 Element area ratio - 2.4 m^2 Mesh face area Thank you in advance!
Ying Peng
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Posted: 1 decade ago 25.04.2012, 19:29 GMT-4
you can not make any modification after importing mesh. Try another way. COMSOL cannot manage mesh. It is not ANSYS.
you can not make any modification after importing mesh. Try another way. COMSOL cannot manage mesh. It is not ANSYS.
Magnus Ringh COMSOL Employee

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Posted: 1 decade ago 27.08.2012, 08:16 GMT-4
Hi,

In COMSOL Multiphysics 4.3 it is possible to explicitly control the partitioning of the imported mesh into domains, faces, edges, and vertices. More information can be found here:
www.comsol.se/products/4.3/#meshandgeometry

Best regards,
Magnus Ringh, COMSOL
Hi, In COMSOL Multiphysics 4.3 it is possible to explicitly control the partitioning of the imported mesh into domains, faces, edges, and vertices. More information can be found here: http://www.comsol.se/products/4.3/#meshandgeometry Best regards, Magnus Ringh, COMSOL

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