[Gmsh] Regular mesh only composed by tetrahedra

[Christophe Geuzaine]

> On 21 Nov 2019, at 19:01, Francisco Pena <fran.pena at gmail.com> wrote:
> 
> Hi, 
> 
> I would like to generate a regular mesh of a cube composed only by tetrahedra.
> 
> When I use Transfinite Volume (see attached file .geo) I end up with a tetrahedral mesh, but the physical entities that define the outer surfaces are applied in triangles that are incompatible with the tetrahedra (see attached file .png).

Indeed, this is a longstanding limitation of the (non-recombined) Transfinite Volume algorithm. We need to fix this... In the meantime, you can

- either use (non-recombined) Extrusion with Layers
- or manually set the interpolation corners in the Transfinite Surfaces (Transfinite Surface{x} = {a,b,c,d};) that do not match, to force the orientation.

Christophe


> 
> With Recombine, I can create a hexahedral mesh but, according to http://onelab.info/pipermail/gmsh/2011/006408.html, there is no easy way to convert it into a tetrahedral mesh .
> 
> Finally, the method TransQuadTri generates not only tetrahedra but also pyramids and prisms. 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine