[Gmsh] Question

[Christophe Geuzaine]

Bayram Yenikaya wrote:

> Hi,
> This is Bayram Yenikaya from University of Minnesota.
> I am working on a project with prof. Bernardo Cockburn.
> Gmsh is great. I would like to ask a question.
> Can Gmsh do the following.
> I will provide mesh points on the boundary of the domain, and also a
> background mesh with appropriate mesh size values.
> I would like it to generate a mesh according to this background mesh,
> but do not add(remove) any points to the boundary.
> I would put boundary points more or less according to backgraound mesh.
> Any response will be greatly appreciated.

Dear Bayram:

Short answer: Gmsh cannot do that at the moment :-(

Long answer:

1) In theory:

* in 2D: it's possible, if the meshes are reasonably "close". Try this
for example: add "Transfinite Line{1:4} = 100;" at the end of
"t1.geo" and use the background mesh "bgmesh.pos". Even if the resulting
mesh is pretty bad, you can see that the boundary constraint is actually
fulfilled.

* in 3D: there is no way to guarantee that the surface mesh will be
respected. It will be *most* of the time, but sometimes it has to be
subdivided.

2) In practice:

Gmsh does not currently allow to read a file containing a boundary mesh
and use it as the basis for subsequent meshing steps. It wouldn't be
extremely hard to implement, but would still require some programming...

Best,

Christophe

-- 
Christophe Geuzaine
Applied and Computational Mathematics, Caltech
geuzaine at acm.caltech.edu - http://geuz.org