[Gmsh] making an equilateral mesh.

[Christophe Geuzaine]

Dr Colin J. Cotter wrote:
> Dear Gmsh list,
>   I have been trying to make a mesh of equilateral triangles by
> extruding a horizontal line at a 60 degree angle (later I will use
> periodic boundary conditions so I have an equilateral mesh on the
> torus). I have noticed that if you do this then the extrusion divides
> the quadrilaterals in the wrong direction and you don't get a Delaunay
> mesh (the equilateral one):
> 
> Point(1) = {0,0,0,0.1};
> Extrude {1,0,0} {
>   Point{1}; Layers{5};
> }
> Extrude {0.5,0.866025403784,0} {
>   Line{1}; Layers{5};
> }
> 
> but it works if you extrude at a -60 degree angle instead:
> 
> Point(1) = {0,0,0,0.1};
> Extrude {1,0,0} {
>   Point{1}; Layers{5};
> }
> Extrude {-0.5,0.866025403784,0} {
>   Line{1}; Layers{5};
> }
> 
> Is there a way to force Gmsh to produce a Delaunay mesh in the first case?

there's no option to subdivide in the other direction... but you could 
use the following trick:

Point(1) = {1,0,0,0.1};
Extrude {-1,0,0} {
   Point{1}; Layers{5};
}
Extrude {0.5,0.866025403784,0} {
   Line{1}; Layers{5};
   }



> 
> all the best
> --cjc
> 
> _______________________________________________
> 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