[Gmsh] tetrahedron mesh size

[David Colignon]

On 16/02/16 12:17, François Nader wrote:
> Thank you for the quick response.
> Actually I have tried the clscale command, but I keep getting the same mesh (attached you can find the geo file).
> Thanks

Your volume is not properly defined:

gmsh polyedre.geo -clscale 0.005 -3
...
...
...
Warning:  Point 31 is replaced by point 14.
   Avoid creating a very short edge (len = 0) (< 5.32173e-10).
   You may try a smaller tolerance (-T) (current is 1e-08)
   or use the option -M0/1 to avoid such replacement.
Delaunay seconds:  0.017112
   Point sorting seconds:  2.8e-05
Creating surface mesh ...
   356 (1068) subfaces (segments).
Surface mesh seconds:  0.000429
Detecting self-intersecting facets...
   Facet #25 intersects facet #30 at triangles:
     (  64,   65,  228) and (  80,   64,  220)
   Facet #25 intersects facet #30 at triangles:
     (  65,   66,  176) and (  66,   80,  220)
   Facet #25 intersects facet #30 at triangles:
     (  65,   66,  176) and (  80,   64,  220)
   Facet #25 intersects facet #30 at triangles:
     (  65,  176,  228) and (  80,   64,  220)
   Facet #25 intersects facet #30 at triangles:
     (  65,   66,  176) and (  66,   80,  220)

!! Found 5 pairs of faces are intersecting.

Self-intersection seconds:  0.071005
Writing nodes.
Writing faces.
Info    : 5 intersecting faces have been saved into 'intersect.pos'
Info    : Done meshing 3D (0.107947 s)
Info    : 254 vertices 548 elements
Error   : ------------------------------
Error   : Mesh generation error summary
Error   :     0 warnings
Error   :     1 error
Error   : Check the full log for details
Error   : ------------------------------
Info    : Writing 'Desktop/polyedre.msh'...
Info    : Done writing 'Desktop/polyedre.msh'
Info    : Stopped on Tue Feb 16 16:53:25 2016


Add the line

Coherence;

at the end of your .geo file.

Regards,

Dave



>
>
>
> ----- Mail original -----
> De: "David Colignon" <david.colignon at ulg.ac.be>
> À: "francois nader" <francois.nader at insa-lyon.fr>, gmsh at geuz.org
> Envoyé: Mardi 16 Février 2016 11:17:04
> Objet: Re: [Gmsh] tetrahedron mesh size
>
> On 16/02/16 11:01, François Nader wrote:
>
>
>
> Hello
> I am using gmsh to mesh a polyhedron .geo file using command line (non-interactive mode). I would like to know how to control the mesh element (tetrahedron) size. For my study, I want to find the effect of mesh size, so I would like to know if it's possible to have meshes between the original mesh and the refined mesh, and how.
>
>
>
>
>
> ace35:~ > gmsh --help
>
> Gmsh, a 3D mesh generator with pre- and post-processing facilities
> Copyright (C) 1997-2016 Christophe Geuzaine and Jean-Francois Remacle
> Usage: /Applications/Gmsh.app/Contents/MacOS/gmsh [options] [files]
> Geometry options:
> -0 Output model, then exit
> -tol float Set geometrical tolerance
> -match Match geometries and meshes
> Mesh options:
> -1, -2, -3 Perform 1D, 2D or 3D mesh generation, then exit
> -o file Specify output file name
> -format string Select output mesh format (auto (default), msh, msh1, msh2, unv, vrml, ply2, stl, mesh, bdf, cgns, p3d, diff, med, ...)
> -bin Use binary format when available
> -refine Perform uniform mesh refinement, then exit
> -part int Partition after batch mesh generation
> -partWeight tri|quad|tet|prism|hex int Weight of a triangle/quad/etc. during partitioning
> -saveall Save all elements (discard physical group definitions)
> -parametric Save vertices with their parametric coordinates
> -algo string Select mesh algorithm (meshadapt, del2d, front2d, delquad, del3d, front3d, mmg3d, pack)
> -smooth int Set number of mesh smoothing steps
> -order int Set mesh order (1, ..., 5)
> -optimize[_netgen] Optimize quality of tetrahedral elements
> -optimize_ho Optimize high order meshes
> -ho_[min,max,nlayers] High-order optimization parameters
> -optimize_lloyd Optimize 2D meshes using Lloyd algorithm
> -clscale float Set global mesh element size scaling factor
>
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>
>
> Regards,
>
> Dave
>