# [Gmsh] Hexa mesh with extruded mesh

Umut Tabak u.tabak at tudelft.nl
Tue Nov 11 00:59:01 CET 2008

```Dear all,

In a hexahedral mesh generation, I can do the tetrahedral meshing
without problems with the below piece of code. But uncommenting the
commented lines results in this problem : My surface is extruded,
however the surfaces in the direction of the extrusion are meshed with
quadrangles and the others with triangles and (I guess) as a result, I
can not get a hexahedral mesh for a simple box geometry.  I am sure I am
missing sth simple from the manual and your help is appreciated.

P.S. I think I can define 8 corners of my box, define lines and surfaces
with transfinite to end up with the hexa mesh. But I wondered the
correct usage of extruded mesh option if I understood correctly from the
manual with the code below(lines uncommented).

Thanks for the replies in advance. Attached also the include file.

Umut

11 Include "truck3d_1r.geo";
12
13 // Transfinite Line{1} = 21 ;
14 // Transfinite Line{2,4} = 11;
15 // Transfinite Line{3} = 21;
16 // Transfinite Surface{10} = {1,2,3,4};
17 // Recombine Surface { 10 };
18 // Physical Surface(4) = {10};
19 // vol[]=Extrude {0.0,0.0,0.5}{
Surface{10};Layers{10};Recombine; };
20 // vol[]=Extrude {0.0,0.0,0.5}{ Surface{10};Layers{10}; };
21 vol[]=Extrude {0.0,0.0,0.5}{ Surface{10}; Layers{5}; };
22 //Transfinite Volume {11} = vol[1] ;
23 Physical Volume (11) = { vol[1] } ;
24 // binary format
25 // Mesh.MshBinary = 1 ;  // GMSH 2.2.4
26 // Mesh.Binary = 1 ;         // GMSH 2.2.5 changed to this
27 // color