[Gmsh] refine by splitting command line options

[Jakub Sistek]

Hello GMSH users,

I am quite new to GMSH and I am now using it for creating block 
structured grids using transfinite meshes. I would like to achieve the 
following behaviour:
1. generate a mesh of second order hexahedra from my geo file
2. refine the mesh by splitting each hexahedra into 8 elements and 
creating new second order hexahedra out of it.

While I can achieve this behaviour in the GUI (refine by splitting + set 
order 2),
I cannot figure out the proper command line options for doing this.

By

gmsh -3 -order 2 mesh.geo

I get the correct second order mesh. But I do not know how to refine it 
now. Simply adding "-refine" option to the above, i.e.

gmsh -3 -order 2 -refine mesh.geo

does not work. If I try to refine the output of the previous command, i.e.

gmsh -refine mesh.msh

I get increased number of elements but with order reduced to 1, leading 
to the same number of nodes.

Combining options to something like

gmsh -order 2 -refine mesh.msh

does not change this.

If I understand it well, my answer in fact boils down to the need of 
"changing an existing mesh in MSH file from linear to quadratic elements 
from the command line".

I am using GMSH v 2.5.1 .

I would appreciate any suggestions. Thanks in advance.

Best regards,

Jakub

-- 
Jakub Sistek, Ph.D.
postdoctoral researcher
Institute of Mathematics of the AS CR
http://www.math.cas.cz/~sistek/
tel: (+420) 222 090 710