[Gmsh] Strange differences between Gmsh 2.2.3 and 2.2.4
Christophe Geuzaine
cgeuzaine at ulg.ac.be
Thu Sep 25 21:14:47 CEST 2008
Moritz Nadler wrote:
> I made a .geo file with gmsh 2.2.3 until it produced a mesh a
> approximately representing what I had in mind. But when I used the same
> geo file with gmsh 2.2.4 I got a totally different mesh ( well the
> geometry remains the same but the mesh density globally and locally
> different. See these gmsh terminal output for a first idea.
>
> Both versions were compiled from source with GCC.
>
>
> Gmsh version 2.2.3
>
> gmsh -rand 1.e-8 circle2.geo -2
> Info : 'gmsh -rand 1.e-8 circle2.geo -2' started on Thu Sep 25
> 19:02:26 2008
> Info : Reading 'circle2.geo'
> Info : Read 'circle2.geo'
> Info : Meshing 1D...
> Info : Meshing curve 1 (Line)
> Info : Meshing curve 2 (Line)
> Info : Meshing curve 3 (Line)
> Info : Meshing curve 4 (Line)
> Info : Meshing curve 5 (Line)
> Info : Meshing curve 6 (Line)
> Info : Meshing curve 7 (Line)
> Info : Meshing curve 8 (Line)
> Info : Meshing curve 9 (Line)
> Info : Meshing curve 10 (Line)
> Info : Meshing curve 11 (Line)
> Info : Meshing curve 12 (Line)
> Info : Meshing curve 13 (Line)
> Info : Meshing curve 14 (Line)
> Info : Meshing curve 15 (Line)
> Info : Meshing curve 16 (Line)
> Info : Meshing curve 100 (Circle)
> Info : Meshing curve 200 (Circle)
> Info : Mesh 1D complete (0.504031 s)
> Info : Mesh
> Info : Meshing 2D...
> Info : Meshing surface 106 (Plane, MeshAdapt+Delaunay)
> Info : Mesh 2D complete (65.8241 s)
> Info : Mesh
> Info : 107605 vertices 215214 elements
> Info : Writing 'circle2.msh'
> Info : Wrote 'circle2.msh'
>
>
> Gmsh version 2.2.4:
>
> gmsh -rand 1e-8 circle2.geo -2
> Info : Reading 'circle2.geo'
> Info : Read 'circle2.geo'
> Info : Meshing 1D...
> Info : Meshing curve 1 (Line)
> Info : Meshing curve 2 (Line)
> Info : Meshing curve 3 (Line)
> Info : Meshing curve 4 (Line)
> Info : Meshing curve 5 (Line)
> Info : Meshing curve 6 (Line)
> Info : Meshing curve 7 (Line)
> Info : Meshing curve 8 (Line)
> Info : Meshing curve 9 (Line)
> Info : Meshing curve 10 (Line)
> Info : Meshing curve 11 (Line)
> Info : Meshing curve 12 (Line)
> Info : Meshing curve 13 (Line)
> Info : Meshing curve 14 (Line)
> Info : Meshing curve 15 (Line)
> Info : Meshing curve 16 (Line)
> Info : Meshing curve 100 (Circle)
> Info : Meshing curve 200 (Circle)
> Info : Mesh 1D complete (0.43 s)
> Info : Mesh
> Info : Meshing 2D...
> Info : Meshing surface 106 (Plane, MeshAdapt+Delaunay)
> Info : Mesh 2D complete (365.69 s)
> Info : Mesh
> Info : 750256 vertices 1500535 elements
> Info : Writing 'circle2.msh'
> Info : Wrote 'circle2.msh'
>
>
> My questions are:
> Can somebody tell me the reason for this?
> Did the syntax change so that what I was using is not longer valid in
> 2.2.4?
> Is there a Bug responsible for this. And if in which version?
>
> Can somebody reproduce my findings ( I attached the .geo file )?
> Or must be something wrong with my installation. ( although I could
> reproduce this already on 2 machines).
Hi Moritz - In 2.2.3 we assumed that when you used Fields, you never
wanted to extend the element sizes from the boundary into the interior.
This was OK if you only had Fields, but prevented a mixture of Fields +
mesh sizes prescribed at geometry vertices and/or according to curvature.
2.2.4 removes this assumption and lets you control everything. In your
case if you do not want to extend the sizes from the boundary, just set
Mesh.CharacteristicLengthExtendFromBoundary = 0;
in your .geo file. This should get the "old" mesh back.
>
>
> kind regards
>
>
> Moritz
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> gmsh mailing list
> gmsh at geuz.org
> http://www.geuz.org/mailman/listinfo/gmsh
--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine