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Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Fri Oct 30, 2015 8:15 pm
by simonz
I am trying to convert my triangular surface meshes into gid volumetric meshes;
Any idea? I've tried a lot programs, but still not find the correct way.
Thanks~

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Mon Nov 02, 2015 8:36 am
by abelcs
Hello,
I don't understand clearly your question. What do you mean with 'convert triangular surface meshes into gid volumetric meshes'? Are you trying to generate tetrahedra meshes of volumes, which contour surfaces are triangles? Or do you want to create prismatic elements from triangular ones?

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Mon Nov 02, 2015 10:48 am
by escolano
If do you want to create the tetrahedra enclosed by your triangular surfaces (the boundary faces of tetras exactly matching your triangles), you can do it writting this:

Code: Select all

Mescape Meshing MeshFromBoundary

and select the triangles that form a closed region to be filled with tetras.

This is not the normal flow of use of GiD, it is more natural to have a geometric volume, apply boundary conditions/materials and then generate the mesh.
As trick, you can create a gometrical surface for each triangle

Code: Select all

Mescape Geometry Create Reconstruct OneSurfForEachElement

and select the triangles to create surfaces from them
then you can create a geometric volume, assign boundary conditions to geometric entities and generate a mesh
(as trick to create a triangle by surface assign a structured number of divisions=1 to all lines. Menu:Mesh->Structured->Lines->Assign number of cells)


To create thin prisms from triangles you can do a similar think, and use the copy tool with an operation of 'offset', and extruding volumes.
You can do it in mesh or geometry (it is better to do it in geometry, to allo use more edition tool, allow re-mesing, and handle assign calculation conditions.

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Mon Nov 02, 2015 8:51 pm
by simonz
thank you so much escolano!!! It helps a lot~~~

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Mon Nov 02, 2015 8:57 pm
by simonz
In addition, escolano, after applying the first code, the GiD asking me about the size of elements to be generated, then how should i decide it?
Thank you so much~

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Tue Nov 03, 2015 10:12 am
by escolano
It is asking for the element size (edge size) to try to be reached by the tetrahedra

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Thu Nov 05, 2015 10:45 pm
by simonz
Hi escolano:
I really appreciate your help, and i just have a small concern here; for the command:
Mescape Geometry Create Reconstruct OneSurfForEachElement
was unknown to the GiD.
You have any idea about it?
Thank you a lot~

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Fri Nov 06, 2015 12:03 pm
by escolano
This command (Geometry Create Reconstruct OneSurfForEachElement) is recent and only exists in last GiD 12.1.xd developer versions.
Dowload the last available developer version.

With old GiD's without this command you can try to do a trick to create a surface by triangle:
1- Export your current triangles with: Files->Export->Using template .bas (only mesh)->DXFSAP2000
2- Import again the .dxf file with Files->Import->DXF...
If 'automatic collapse after import' was not set while importing the DXF do you need to do a model collapse with a small tolerance (else surfaces are unconnected)

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Sat Nov 14, 2015 9:11 pm
by simonz
Hi escolano:
i've tried your suggestions and i am still have some questions about the mesh generated by using the code:Mescape Meshing MeshFromBoundary.
is the mesh generated by applying this code will be a volume mesh?
if not, then should i use the code: Mescape Geometry Create Reconstruct OneSurfForEachElement?
the attached picture is for the one i generated by using the first code. after this the second one cannot be applied to it.
I would really appreciate if you take a look and provide me some help on how to generate it into a volumetric mesh by steps.

Thanks a lot!!

Re: Triangulate Surface Mesh to GiD volumetric Mesh

Posted: Mon Nov 16, 2015 11:14 am
by escolano
Mescape Meshing MeshFromBoundary
will generate the volume mesh (tetrahedra) from a closed surface boundary (of triangles).
Depending on other contextual words (click righ-mouse button to show the contextual menu) the original triangles will be deleted or not,
and different volume mesher algorithms and parameters could be selected: advancing front, delaunay (tetgen),...

You can check the kind and amount of elements of your current mesh for example with Utilities->Status...