[Gmsh] Bug with periodic entities in extruded meshes with layers?

[Marco Tiberga]

Dear Gmsh developers,

I have recently moved from Gmsh 3.0.6 to the most recent 4.3.0, and I have noticed that the .msh files for extruded meshes with layers are slightly different than before, because they contain periodicity relations.
To me this is puzzling, because I do not have any periodic mesh. Why are the periodicity relations written even on non-periodic meshes? is there a way to turn this off?

Second, I have noticed that Gmsh is returning an error when reading these .msh files. I have attached two meshes (2D and 3D) that prove this: the .msh files have been generated from the attached .geo ones. For example, when I open square.msh, I get "Error: Cannot find periodic counterpart of vertex 3 on edge 2 nor on 2".
Since these are two extremely simple meshes, I was wondering whether there is a bug in the definition of the periodicity relations, or whether some commands I am using need to be changed with the new Gmsh version.

For your information, I have to use the MSH 2.2 format for compatibility with my CFD code.

Thanks.

Best regards,
Marco Tiberga
PhD candidate
Delft University of Technology
Faculty of Applied Sciences
Radiation Science & Technology Department
Mekelweg 15, 2629 JB Delft, The Netherlands
E-Mail: m.tiberga at tudelft.nl<mailto:m.tiberga at tudelft.nl>
Website: http://www.nera.rst.tudelft.nl/


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