[Gmsh] Problems with 2D mesh

[Christophe Geuzaine]

> On 20 Nov 2018, at 09:10, Alessandro Vicini <alessandro.vicini at sitael.com> wrote:
> 
> Hello Christophe,
>  
> the surface mesh is wrong if you set Mesh.CharacteristicLengthExtendFromBoundary = 0. I have just tried latest version 4.0.5, but the behavior is the same…

The surface mesh looks correct to me: you constrain the size of the line elements on the edges of the parallelepipeds with Transfinite constraints, but the mesh size field computed by attractor_TestCase.geo on these parallelepipeds is much larger than this constraint (see the picture I sent in my previous mail). You thus get refined edges, but the largest possible surface elements connected to them. Remove your Transfinite constraints and you will obtain the correct uniform (but very coarse) mesh on the parallelepipeds. Setting Mesh.CharacteristicLengthExtendFromBoundary = 1 will use the edge size constraint to set the size of the triangles - discarding your coarser mesh size specification done in attractor_TestCase.geo, leading to a denser, uniform mesh.

So everything seems to be working as expected...


>  
> A.
>  
>  
> Da: Christophe Geuzaine [mailto:cgeuzaine at uliege.be] 
> Inviato: lunedì 19 novembre 2018 19:41
> A: Alessandro Vicini
> Cc: gmsh at onelab.info
> Oggetto: Re: [Gmsh] Problems with 2D mesh
>  
> 
> 
> 
> On 19 Nov 2018, at 12:25, Alessandro Vicini <alessandro.vicini at sitael.com> wrote:
> 
> 
> With the attached geo file (TestCase) I have a problem in the 2D mesh of some of the internal faces (see attached picture) if I set Mesh.CharacteristicLengthExtendFromBoundary = 0 (which is what I would like to do), regardless of the meshing algorithm. The mesh is ok when 
> Mesh.CharacteristicLengthExtendFromBoundary = 1. I'm using v4.0.1. Is there a way to solve this? Thank you.
> 
>  
> The mesh size looks OK to me given your mesh size field (I've tested with Gmsh 4.0.5):
>  
>  
> <image001.png>
>  
> 
> 
> A.V.
> <TestCase.geo><attractor_TestCase.geo><TestCase.jpg>_______________________________________________
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> — 
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science 
> http://www.montefiore.ulg.ac.be/~geuzaine
> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine

Free software: http://gmsh.info | http://getdp.info | http://onelab.info