[Gmsh] Problem of non coherence.

[Christophe Geuzaine]

Olivier Allain wrote:
> Dear sir,
> 
>  I am a new user of gmsh. This tool is very smart and easy to use. I
> thank you for your effort. I have a question with a problem of
> coherence between two surfaces. It appears in 3D using a extruded zone
>  and an unstructured zone. If you look at the boundary between the
> center and the external circle it appears the mesh is not conform. It
> seems the mesh generate 2 volumes without taking into account there is
>  a common face. It runs with Netgen but it crashes with Tetgen, and
> Netgen seems to be not able to run for a big case. Is there an option
> for Tetgen in order to solve this problem ?

Unfortunately, no: a 3D Delaunay algorithm cannot be guaranteed to
recover the surface triangulation (it sometimes needs to swap edges or
insert new points on the boundary).

We could try to make the meshes match at the interface a posteriori, but
that would destroy the structure of the structured mesh... It's the main
reason why we keep Netgen around.

(PS: In your particular example you could extrude the whole mesh: cf.
attached file.)


> 
>  Best Regards,
>  O. Allain
> 
> 
> ------------------------------------------------------------------------
> 
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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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