[Gmsh] Gmsh-4.0.4 Volume mesh issue

[Simone GREMMO]

Dear Christophe,

thank you very much for your reply. I downloaded the latest snapshot and now I can get the mesh as expected. I will continue my testing.


One more question: I have seen that with Gmsh 4 you have introduced many modifications to the mesh generation algorithms. Could you tell me the section where the pyramids are added and "inflated" inside the domain?


In a previous version (I think 2.x) it was in "MeshDelaunayVolumeTetgen" in meshGRegion.cpp, but now, I cannot find the relevant section in the new implementation.

In the old code I introduced a modification (after a discussion with prof. Remacle) to this part and would like to try to replicate it also in the latest version of Gmsh.


Thanks in advance,

Simone G.

________________________________
From: Christophe Geuzaine <cgeuzaine at uliege.be>
Sent: Monday, November 12, 2018 3:33:25 PM
To: Simone GREMMO
Cc: gmsh at onelab.info
Subject: Re: [Gmsh] Gmsh-4.0.4 Volume mesh issue


Dear Simone,

Indeed, Gmsh 4.0.0 -> 4.0.4 do not have the ability to automatically create hybrid tetrahedral+pyramidal meshes (your surface contains quadrangles).

The latest snapshot (future Gmsh 4.0.5 or Gmsh 4.1) has a new algorithm to generate such meshes, similar but more general to what we did in Gmsh 3. Give it a try and let us know how it works out for you?

Christophe


> On 12 Nov 2018, at 14:38, Simone GREMMO <Simone.GREMMO at umons.ac.be> wrote:
>
> Dear all,
> I have just downloaded the last version of Gmsh (4.0.4), but I am facing a problem with the generation of a "simple" volume mesh.
>
> I would like to mesh a volume delimited by a surface mesh in .msh format, but it looks like Gmsh cannot create the volume mesh.
> Error Message is :
> .....
> Info    : Boundary Recovery...
> Info    : Writing to GRegion...
> Info    : Reconstruct time : 0.116395 sec
> Error   : No tetrahedra in region 5
> Info    : 3D point insertion terminated (3195 points created):
> Info    :  - 0 Delaunay cavities modified for star shapeness
> Info    :  - 0 points could not be inserted
> Info    :  - 0 tetrahedra created in 1.6e-05 sec. (0 tets/sec.)
> Error   : No tetrahedra in region 5
> Info    : Done meshing 3D (0.133228 s)
> Info    : 4857 vertices 6617 elements
> Error   : ------------------------------
> Error   : Mesh generation error summary
> Error   :     0 warnings
> Error   :     2 errors
> Error   : Check the full log for details
> Error   : ------------------------------
>
> I am attaching the .geo file I have created as well as the surface mesh I used. To launch the mesh generation I run the command:
> gmsh-4.0.4 createGeom.geo -3 -o volumeMesh.msh
>
> Note that the same test case is successfully meshed using Gmsh version 3.0.6.
>
> Do you have any suggestion on how to solve the problem?
> Is it possible that the surface mesh, containing both triangles and quadrangles is at the origin of the problem?
>
> Thanks in advance for your suggestions.
> Regards,
> Simone G.
>
> <createGeom.geo><surfaceMesh.msh>_______________________________________________
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—
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine

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