Re: [Libmesh-users] Face ids in gmesh and libMesh

[John P. <jwp...@gm...>]

On Mon, Apr 29, 2019 at 6:02 PM Nikrouz <nik...@gm...> wrote:

> Dear all libMesh users,
>
> I have produced a 3D msh file by Gmesh but I do not define any group
> surface in Gmesh.
>
> In order to identify different faces, is there any class or method in
> libMesh or it is neccsary to define id for msh file in gmesh?
>
> The mentioned faces will be used for boundary conditions.
>

Boundary conditions are specified by "Physical" groups in the gmsh input
file. libMesh reads sections like the following:

$PhysicalNames
5
1 2 "left"
1 3 "right"
1 4 "top"
1 5 "bottom"
$EndPhysicalNames

and converts them into named sidesets with the ids specified.

You might also find this tutorial helpful:
https://albertsk.files.wordpress.com/2012/12/gmsh_tutorial.pdf

-- 
John