[Gmsh] Periodic Surface Error: Different number of points for periodic correspondance between surfaces.

[Christophe Geuzaine]

> On 22 Jul 2020, at 12:26, lucia.cobian <lucia.cobian at imdea.org> wrote:
> 
> Dear all,
> 
> I am trying to build a periodic mesh for a complex geometry, made by cylinders, which is bounded by a cube (Boolean intersection). To do the periodic mesh I have used Periodic Surface {} = {} Translate {} command to make it periodic in the three opposite surfaces (xy,xz,yz) of the intersected cube, as indicated in the attached .geo file.
> 
> However, I receive the following errors:
> 
> “No  corresponding point x for periodic connection of surface xx to yy” or “Different number of points (a vs b) for periodic correspondence between surfaces aa and bb”.
> 
> I have tried to fix the error without any success. I would like to know why is this happening and how can the .geo file be modified to fix the problem.
> 
> I would appreciate if someone could help me with this issue.

Nothing guarantees that the surfaces you get by querying by bounding box (e.g. topx() and bottomx()) will be returned in the same order.

See the solution proposed in tutorial 18 (https://gitlab.onelab.info/gmsh/gmsh/-/blob/master/tutorial/t18.geo).

Christophe


> 
> Thank you very much,
> 
> Lucia<periodic_mesh.geo>_______________________________________________
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine