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Mesh Data Format

Posted 19 sept. 2012, 16:59 UTC−4 Mesh Version 4.3 4 Replies

John R Puentes
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Hi,

I have a 3D object that I'm trying to mesh. I exported the mesh data file and tried to understand its contents and ran into some issues.

How are the geometric entity indices related to the mesh point coordinates? I also don't understand what the number of parameter values per element are.

Also, there are 2 listings for geometric indices, I'm assuming this is so because there are 2 types of elements in my mesh: tetrahedral and prisms. Is this assumption correct?

When the number of nodes per element is mentioned, does it refer to the the specific nodes that are interconnected?
I guess I'm having overall problems interpreting the mesh information. I'm attaching the file in case it might be useful .

Any help would be appreciated.
Thank you,

Attachments:

4 Replies Last Post 20 sept. 2012, 16:33 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 20 sept. 2012, 01:37 UTC−4
Hi

I cannot tell, as the nice thing about COMSOL is that you do not really need to bother about the mesh, from the moment your mesh is dense enough to resolve correctly the dependent variables and their gradients. With COMSOL you consider only the mesh as a "discretisation" parameter of your physics equations. All physics is defined in the geometry Entities: Domains and Boundaries not on the mesh & Nodes (in contrary to older FEM tools)

The only time I had to look into the mesh was when I tried to import export to other FEM tools, as this is sometimes demanded by my clients. This I had to give up, and now I pay external services to redo the models in the appropriate tools for these clients, not my favourite approach, but that is not really a COMSOL issue, its rather that there are NO common exchange platform defined for FEM tools


--
Good luck
Ivar
Hi I cannot tell, as the nice thing about COMSOL is that you do not really need to bother about the mesh, from the moment your mesh is dense enough to resolve correctly the dependent variables and their gradients. With COMSOL you consider only the mesh as a "discretisation" parameter of your physics equations. All physics is defined in the geometry Entities: Domains and Boundaries not on the mesh & Nodes (in contrary to older FEM tools) The only time I had to look into the mesh was when I tried to import export to other FEM tools, as this is sometimes demanded by my clients. This I had to give up, and now I pay external services to redo the models in the appropriate tools for these clients, not my favourite approach, but that is not really a COMSOL issue, its rather that there are NO common exchange platform defined for FEM tools -- Good luck Ivar
John R Puentes
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Posted: 1 decade ago 20 sept. 2012, 10:33 UTC−4
Hi Ivan,

The issue was that I actually need to know how the mesh works because I need to arrange the mesh in file that a code of mine in Fortran can use. I need to accurately input the geometry of the mesh so I can run this Fortran code.
So basically what you're telling me is that the only solution would be to hire external services for this purpose?

Thanks,
Hi Ivan, The issue was that I actually need to know how the mesh works because I need to arrange the mesh in file that a code of mine in Fortran can use. I need to accurately input the geometry of the mesh so I can run this Fortran code. So basically what you're telling me is that the only solution would be to hire external services for this purpose? Thanks,
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 20 sept. 2012, 10:51 UTC−4
Hi

No, probably not for your case, for me it's because I need FEM delivered in other formats as formal delivery for some of my projects.

In your case, either you can get some support from "support" of COMSOL who are the only ones really knowing how it's formatted, or you manage to analyse the cases yourself as you are doing,. Do not forget to dive into the Java I/F there might be other info in there ;)

--
Good luck
Ivar
Hi No, probably not for your case, for me it's because I need FEM delivered in other formats as formal delivery for some of my projects. In your case, either you can get some support from "support" of COMSOL who are the only ones really knowing how it's formatted, or you manage to analyse the cases yourself as you are doing,. Do not forget to dive into the Java I/F there might be other info in there ;) -- Good luck Ivar
Alexander Kuznetsov
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Posted: 1 decade ago 20 sept. 2012, 16:33 UTC−4
I think you can export mesh coordinates in data format. In Results-Export, choose data. For Output options, choose "Points to evaluate in: take from data set". Under "Expression", put three coordinates (x, y, z). It should work.
I think you can export mesh coordinates in data format. In Results-Export, choose data. For Output options, choose "Points to evaluate in: take from data set". Under "Expression", put three coordinates (x, y, z). It should work.

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