[Gmsh] Problem defining a compound geometry

[David Colignon]

On 09/12/11 11:45, Harish Narayanan wrote:

> Hello all,
>
> I am having difficulty defining compound geometries. The problem I
> originally experienced was for a more complicated union of volumes, but
> the same issue shows up for the simple following case involving trying
> to merge two unit squares.
>
> lc = 0.25;
>
> Point(1) = {0, 0, 0, lc};
> Point(2) = {1, 0, 0, lc};
> Point(3) = {1, 1, 0, lc};
> Point(4) = {0, 1, 0, lc};
>
> Line(1) = {1, 2};
> Line(2) = {2, 3};
> Line(3) = {3, 4};
> Line(4) = {4, 1};
> Line Loop(5) = {1, 2, 3, 4};
>
> Plane Surface(6) = {5};
> Translate {-0.5, -0.5, 0.0} {
>      Duplicata{Surface{6};}
> } // Surface(7)
> Compound Surface (8) = {6, 7};
>
> //Mesh.RemeshAlgorithm=1;
>
> 1. If I try the code above without Mesh.RemeshAlgorithm set to 1, Gmsh
> crashes with:
>
> Info    : Meshing surface 8 (Compound surface, MeshAdapt)
> Warning : Wrong topology: Genus=-1, Nb boundaries=2, AR=1.5
> Error   : For remeshing your geometry, you should enable the automatic
> remeshing algorithm.
> Error   : Add 'Mesh.RemeshAlgorithm=1;' in your geo file or through the
> Fltk window (Options>  Mesh>  General)
>
> 2. If I try it Mesh.RemeshAlgorithm set to 1, Gmsh seemingly hangs while
> attempting to complete the meshing process.
>
> Could someone please help me understand what is going on? I am assuming
> that Compound Surface (and Volume) are meant to take unions of
> geometries. Have I misunderstood what they are for?


Hi Harish,

yes, Gmsh is not a solid modeler and cannot take union of surfaces/volumes.

For the meaning of "Compound" , see

https://geuz.org/trac/gmsh/wiki/STLRemeshing  (username: gmsh, password: gmsh)

Regards,

Dave


-- 
David Colignon, Ph.D.
Collaborateur Logistique du F.R.S.-FNRS
CÉCI - Consortium des Équipements de Calcul Intensif
ACE - Applied & Computational Electromagnetics
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Université de Liège
4000 Liège - BELGIQUE
Tél: +32 (0)4 366 37 32
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>
> Thanks,
> Harish
>
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