[Gmsh] 3D meshing

[Cristóbal Bertoglio B.]

Hi

so I re-run the meshing in old testcases and the Delaunay (plus the
two types of optimization) gives always better meshes than in the
frontal case, and without tetras with the 4 vertices on the external
surface.

The price is that it creates much more nodes, but the real problem is
it creates also additional triangles on the surface (what it is not
convenient for me since I'm doing FSI).

Hence, it is possible to tell gmsh not to create additional triangles
on the surface ? (if yes this would be already great).

Thanks

Cristobal.

2011/9/1 Christophe Geuzaine <cgeuzaine at ulg.ac.be>:
>
> On 31 Aug 2011, at 14:13, Cristóbal Bertoglio B. wrote:
>
>> Hi
>>
>> I'm trying to construct a volumetric mesh from an already existing surface mesh.
>>
>> In past tests I was using the Frontal algorithm (+ netgen
>> optimization) since it gave me less nodes, no surface triangles and no
>> tetrahedra with the 4 nodes on the external surface. However, when
>> running it for this example gives several errors of type I indicate
>> bellow.
>>
>> In contrast,  Algorithm 1 works perfectly (however it produces more
>> nodes, create surface triangles and give me tetrahedra with the 4
>> nodes on the external surface, all things that I want to avoid).
>>
>> Does some know the reason why Delaunay works and Frontal doesn't ?
>>
>
> Hi Cristobal,
>
> The frontal algorithm is definitely less robust than the Delaunay. Do you still get bad tets if you optimize your mesh ("Optimize" and/or "Optimize Netgen") in the mesh menu?
>
>
>
>> The mesh is also attached.
>>
>> Thanks in advance,
>>
>> Cristobal.
>>
>> -------------
>>
>> Info    : Meshing volume 0 (Frontal)
>> Info    : Region 0 Face 1, 3 intersect
>> Info    : CalcLocalH: 13932 Points 0 Elements 27860 Surface Elements
>> Info    : Check subdomain 1 / 1
>> Info    : 27860 open elements
>> Error   : ERROR: Edge 20 - 33 multiple times in surface mesh
>> ......
>> Error   : ERROR: Surface mesh not consistent
>> Error   : ERROR: Stop meshing since surface mesh not consistent
>> Info    : Mesh 3D complete (1.84027 s)
>> Info    : 13932 vertices 27860 elements
>> Error   : ------------------------------
>> Error   : Mesh generation error summary
>> Error   :     0 warnings
>> Error   :   201 errors
>> Error   : Check the full log for details
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>
> --
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://www.montefiore.ulg.ac.be/~geuzaine
>
>
>
>