[Gmsh] Compound lines in STL

Vincent Libertiaux vincent.libertiaux at gmail.com
Tue Sep 9 17:27:52 CEST 2014


Hi Bart,

Could you please check what happens if you remove the CreateTopology
command ?

V.

2014-09-03 5:17 GMT-05:00 Bart Vermeulen <bart.vermeulen at wur.nl>:

> Dear all,
>
> I am trying to create a mesh starting with a STL model. This model
> consists of 6 different surfaces. I use the file included below (quite
> similar to one of the tutorials). When I load this into gmsh I can see the
> geometry with the different surfaces. At the corners of each of the
> surfaces there is a point (4 points for each surface). The Compound lines
> connect these points directly instead of following the geometry (see
> attached screenshot). Obviously the meshing fails.
>
> Any idea how to properly define the compound lines? (The surfaces ar OK)
>
> Thanks in advance,
> Bart Vermeulen
>
>
>
> Merge "mmbendo.stl";
> CreateTopology;
>
> // We can now define a compound line (resp. surface) for each discrete
> // line (resp. surface) in the model
> ll[] = Line "*";
> For j In {0 : #ll[]-1}
>   Compound Line(newl) = ll[j];
> EndFor
> ss[] = Surface "*";
> s = news;
> For i In {0 : #ss[]-1}
>   Compound Surface(s+i) = ss[i];
> EndFor
>
> // And we can create the volume based on the new compound entities
> Surface Loop(1) = {s : s + #ss[]-1};
> Volume(1) = {1};
>
> Physical Surface(1) = {s : s + #ss[]-1};
> Physical Volume(1) = 1;
>
> uniform = 1;
> If(uniform)
>   // uniform mesh size...
>   Mesh.CharacteristicLengthMin = 15;
>   Mesh.CharacteristicLengthMax = 15;
> EndIf
> If(!uniform)
>   // ... or apply a funny mesh size field, just because we can :-)
>   Field[1] = MathEval;
>   Field[1].F = "2*Sin((x+y)/5) + 3";
>   Background Field = 1;
> EndIf
>
> Mesh.RemeshAlgorithm = 0; // (0) no split (1) automatic (2) automatic only
> with metis
> Mesh.RemeshParametrization = 7; // (0) harmonic (1) conformal spectral (7)
> conformal finite element
> Geometry.HideCompounds = 0; // don't hide the compound entities
> Mesh.Algorithm = 6; // Frontal
>
> --
> Bart Vermeulen
> Wageningen University, Department of Environmental Sciences
> Hydrology and Quantitative Water Management Group
> Postal address: Postbus 47, 6700AA Wageningen,The Netherlands
> Visiting address: Room 0.C027, Droevendaalsesteeg 3,6708PB Wageningen, The
> Netherlands
> Tel. +31-317-482765 Fax +31-317-419000
> email: bart.vermeulen at wur.nl
>
>
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>
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