[Gmsh] CreateGeometry for multiple Surfaces / Volumes

[Christophe Geuzaine]

> On 29 Apr 2019, at 09:22, Sebastian Blauth <blauths at itwm.fraunhofer.de> wrote:
> 
> Hi,
> 
> 
> I've got a question regarding the CreateGeometry command in conjunction with multiple Surfaces.
> 
> I would like to use gmsh for remeshing a transformed mesh (which was orignally created with gmsh) and I think that the CreateGeometry command would do exactly what I want: Take a discrete mesh and extract the underlying geometry (ideally with the same indices) so that I can perform a remeshing.


CreateGeometry will create a parametrization of the underlying mesh, so that it can be remeshed. Here however since you only save the triangles (not the line elements on the curves, due to your physical definitions), the 1D mesh is empty - leading to an empty surface mesh. Note that I cannot reproduce the seg fault with the latest Gmsh version - which version do you use?

To make it work with Gmsh 4.3, just remove the "Physical" definitions on test.geo. You should also remove "Coherence Mesh" from remesh.geo, as the mesh is already conformal.

Note that we are (again...) reworking the remeshing pipeline to make it more robust: the parametrizations will now be persistant (saved in the mesh file), and the internal workflow will make it possible to use with discrete entities all of the features currently reserved for CAD entities: mesh size depending on curvature, parallel meshing, high-order meshes, etc. We plan to release this in Gmsh 4.4. or 4.5.

Christophe





> 
> 
> However, this does not work if I have multiple (adjacent?) surfaces in my mesh. There, I just get a segmentation fault.
> 
> 
> I've included a minimal working example, where test.geo defines my "deformed" mesh (unfortunately I cannot send the mesh file directly, but I generated it just using "gmsh test.geo -2", and I want to remesh this using remesh.geo
> 
> 
> I really appreciate any help on this.
> 
> Best regards,
> 
> Sebastian
> 
> -- 
> Sebastian Blauth
> Fraunhofer-Institut für
> Techno- und Wirtschaftsmathematik ITWM
> Fraunhofer-Platz 1, 67663 Kaiserslautern
> Telefon: +49 631 31600-4968
> sebastian.blauth at itwm.fraunhofer.de
> www.itwm.fraunhofer.de
> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine