[Gmsh] Gmsh and postprocessing

Martin Vymazal martin.vymazal at vki.ac.be
Thu Dec 6 12:09:25 CET 2007

Hi all,

 I'm currently a student at the von Karman Institute for Fluid Dynamics in
Belgium and I'm supposed to incorporate a gmsh writer into COOLFluid, a
numerical software package being developed here at the institute (if
you're interested, visit http://coolfluidsrv.vki.ac.be/coolfluid). For
the start, I would like to have an output of a simulation on second order
triangles that I could postprocess using gmsh. I have a couple of
questions concerning the file formats used by gmsh.
  First, it seems like the description of mesh geometry (nodal
coordinates, elements, etc.) and the output data (i.e. the result of my
simulation) have to be kept in separate files. Is there a way to have
these data in a single file ? Since the datasets may be possibly quite
large, I'm interested in the version 2.0 ascii or binary formats, not
the old format.
  Second, if I understand it correctly, there can be stored 1,3 or 9
values per node in a *.pos  file (if I use scalar, vector or tensor
triangles). However, if you consider 2D compressible Euler simulation,
for example, you will have 5 values per node (density,2 velocity
components, pressure, energy). Is it possible to store other number of
solution values per node that 1/3/9 ? Maybe there's a way to use
user-defined datastructures ? I was also looking for some example files
at gmsh wiki, but most of them are the 'mesh' files, not postprocessing
ones. Maybe it would be useful to upload some, if anybody is willing to
share them.
  I tried to find the answers to my questions in the documentation and in
the forum, but I'm new to gmsh. I apologize for bothering you if the
answer can be found easily, maybe I overlooked something.
  I also know that the priority of gmsh is meshing, not visualization. If
you know about any other (free) alternatives that allow the user to
display curvilinear (2nd or possibly higher order) elements, I'd be
happy to hear about them. Thank you for your reply.

                          Martin Vymazal