[Gmsh] R: R: Problems with 2D mesh

[Alessandro Vicini]

Never mind, just found out, it depends on the characteristic length of the points used to generate the surfaces...


-----Messaggio originale-----
Da: gmsh [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be] Per conto di Alessandro Vicini
Inviato: giovedì 22 novembre 2018 09:44
A: Christophe Geuzaine
Cc: gmsh at onelab.info
Oggetto: [Gmsh] R: Problems with 2D mesh


Ok, got it.

Another question then on the behavior of Mesh.CharacteristicLengthExtendFromBoundary: why does it also affects the mesh density on the outer surface (where no transfinite lines are set)? Thank you.

Alessandro


-----Messaggio originale-----
Da: Christophe Geuzaine [mailto:cgeuzaine at uliege.be] 
Inviato: mercoledì 21 novembre 2018 17:32
A: Alessandro Vicini
Cc: gmsh at onelab.info
Oggetto: Re: [Gmsh] Problems with 2D mesh



> 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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