# [Gmsh] gmesh // char. lenth, unv format

Alper Corlu corlua at dept.physics.upenn.edu
Fri Jul 27 18:49:25 CEST 2001

```Hi ,

thanks for the answer. But to tell the truth I am a beginner on finite
element method and mesh generation, so the only thing I know about mesh
size in a mesh is the max of the diameters of the elements (diameter of an
element defined as the largest edge of the element) in the volume.
1)So what do you mean by mesh sizes at each point? (you may just show me
a reference on meshing or finite element)
2) What is the unv format? Is it some standard file output for
meshes? Can you supply info or reference on this format?
thanks a lot
alper

On Thu, 26 Jul 2001, Christophe Geuzaine wrote:

> Alper Corlu wrote:
> >
> > Hi
> >
> > I am Alper Corlu. I am a physics Phd student at university of
> > Pennsylvania. I am currently working on finite element method and the code
> > I have is using your Gmesh program. We are trying to understand the
> > program and asking you if there is a manual for the program? The tutorial
> > is fine but we cant find answers to all the questions in tutorial like
> > characteristic length, how to set it, how to use it ..etc.
>
> Unfortunately, there is no complete manual for Gmsh at the moment. But
> don't hesitate to send specific questions to the mailing list
> (mailto:gmsh at geuz.org). As for the characteristic lengths, there are
> three main possibilities:
>
> 1) Specify a target mesh size as the fourth coordinate of the geometry
> points. These mesh sizes will be linearly interpolated in the structure
> to produce the actual mesh sizes at each point in the volume.
>
> 2) Use attractors with the anisotropic mesh generator (see
> tutorial/t7.geo).
>
> 3) Define a real background mesh, from which the actual mesh sizes will
> be interpolated. Try for example 'gmsh tutorial/t1 -bgm
> tutorial/bgmesh.pos -2'.
>
> Christophe
>
> --
> 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
>

```