[Gmsh] Q-Morph algorithm on parametric space: questions related to the c++ code.

[Jean_Baptiste Faes]

Dear gmsh developper's team,

I am Jean-Baptiste FAES, quantum physicist. Since some months, I am interested in computational fluid dynamics. I thus learned about it and tried to do some test cases in fluid-flow modeling. In most of my applications I make use of your software "gmsh", because it is very convenient to use.

I discovered during my studies that hexahedral mesh offers the best support for CFD calculations using finite volume method. Unfortunately, gmsh doesn't offer yet an unstructured hexaedral mesh generator. I thus decided to do my own one, based on the H-Morph algorithm. My aim is to incorporate it in gmsh, but I faced some problems to understand your C++ code. I thus was wondering if you could help me on one or two points.

I am currently working on Q-Morph algorithm. My computer code uses as input an stl file that is output from a triangulated surface meshed with gmsh. You can see in attached file some examples of 2D surfaces meshed with gmsh, and then converted to quad with my program (and visualized with gmsh in geo format). It works quite well for plane surfaces, or surfaces with small curvature. Now I would like to take advantage of the parametric coordinates used in gmsh. Indeed, if I could apply the Q-Morph algorithm directly on the parametric 2D space used in gmsh, I suppose that I would be able to mesh every type of surface.

My first question is thus the following: Where in your code can I extract the parametric mesh ? I found that some 'writeMSH' routines have an argument 'saveParametric',  but I'm not sure the variables '_u' and '_v' correspond to the 2D-parametric coordinates.

My second question is: once I have transformed the triangular mesh into a quad mesh, how can I put this mesh in gmsh in such a way it is recognized as a 3D surface mesh that will be further used for volume meshing ?

I thank you very much for your attention.

Best regards,
JB FAES


      
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