[Gmsh] gmsh extrusion jump some number

Christophe Geuzaine Christophe.Geuzaine at ulg.ac.be
Fri Sep 7 09:39:46 CEST 2001

"antric at inwind.it" wrote:
> When I made extrusion gmsh jump some number, and I should renumber manually!
> Are there any way?

Unless you apply a predefined numbering scheme (cf. below) to the new
geometrical entities that are created during the extrusion process, it
is very difficult to reference them automatically (think of degenerated
cases, arbitrary shapes to extrude, etc.). At the moment, the only
possibility is thus to select the entities to extrude interactively (or
to guess the numbers if you extrude things repetitively, e.g. using the
newreg variable).

Though, if your extrusion is a simple extrusion along the z-axis (only),
you may want to use our simplified extrusion generator, which keeps the
information about the original geometrical entity in the numbering of
all derived ones. Try e.g. 'gmsh -extrude -recombine -saveall -3' on a
2D geometry defined in the xy plane (you will be prompted to give some
information about the number of layers, the number of elements per
layer, etc.). As you will notice, all the elements generated with this
simplified algorithm get region numbers affected in a deterministic way,

volumes elements: 300e6 + layer_num * 1e6 + origin_surface_num

surface elements in the xy plane: 200e6 + layer_num * 1e6 +

perpendicular surfaces: 100e6 + layer_num * 1e6 + origin_curve_num

perpendicular lines: 400e6 + layer_num * 1e6 + origin_point_num


> thank you
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Christophe Geuzaine

Tel: 32 (0) 4 366 37 10    http://geuz.org
Fax: 32 (0) 4 366 29 10    mailto:Christophe.Geuzaine at ulg.ac.be