[Gmsh] Re: Some quesions

[Christophe Geuzaine]

Henry Liu wrote:
>   Hello, Gmsh teams
> 
> I am using Gmsh1.55 version to create volume mesh used
> for finite element analysis. I have several questions
> regarding its usage.
> 
> 1. How the 'Merge' option works? 

It simply appends the file to the currently loaded file(s).

> What is the detailed
> requirement on the file format of two models (supposed
> I have surface mesh or volume mesh) especially on
> those entiries at the merging interface definition?

Gmsh will complain if there are duplicate elements (nothing is 
implemented at the moment to handle the merge of mesh files that share 
interfaces). Merge is mostly useful to merge multiple post-processing 
views or scripts atop a geometry and/or a mesh.

> 
> 2. Can Gmsh output the boundary node coordinates of a
> volume mesh in a single file or include this
> information in the output .msh file? 

Gmsh always saves all the nodes. Just define a Physical Surface if you 
want to tag the boundary elements: you can then easily retrieve the 
boundary nodes by checking which nodes belong to these boundary elements.

> 
> 3. Flat tetrahedron is generated after optimization
> steps (three or more) sometimes, but it did not
> happens at the first 3D mesh. 

That should not happen. Can you send the .geo file?

Take care,

Christophe

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