[Gmsh] Boundary layers in gmsh?

Eric Nutsch ericnutsch at gmail.com
Fri Feb 26 08:39:57 CET 2010


It appears that the surface loop method to the boundary layer will
work in most all cases, but I may have found a more efficient way.

The BL extrude command returns a volume number as well. If it were
possible to take the farfield and preform a boolean operation with the
BL volumes, it would make the process very simple even for complex

I attempted this for in your sphere example:
Volume(1001) = {1002, 1,2,3,4,5,6,7,8};
 ,but gmsh replied with "Unknown surface loop 1"

Is there any way to convert a volume (created via extrude for example)
to be converted into a surface loop?
Perhaps I am missing an important leap in the coding structure, but if
it was possible it would be an extremely handy function.

What are your thoughts?

Eric Nutsch

On Wed, Feb 24, 2010 at 4:03 AM, Christophe Geuzaine
<cgeuzaine at ulg.ac.be> wrote:
> On 24/02/10 11:26, julien hoessler wrote:
>> Hi Eric,
>> If it is a flat surface or if you know where the interface would be
>> located you can just move your domain line/surface to the interface and
>> extrude it towards the outside, but otherwise I can't seem to find a way
>> to link the interface with the rest of the mesh
> Hi Guys - boundary layers are still a bit experimental, but the basics are
> there to connect them with other geometrical entities. Attached are two
> examples:
> * sphere_boundary_layer.geo shows how to connect volumes to boundary layer
> faces ;
> * t1_boundary_layer_connection.geo shows how you can also connect things to
> the lines or vertices created during the boundary layer generation.
> Retrieving the id numbers of the extruded entities can be done in a script
> the usual way (list[] = Extrude...), but as usual this only gives access to
> the ids of the "top" surface, the new volume and the "lateral" surfaces.
> To retrieve the ids of the new lines and the new points, you have at the
> moment to resort to the GUI (in "Tools->Options->General->General" select
> "Enable mouse hover over meshes" to see the numbers displayed at the bottom
> of the graphical window).
> Hope this helps,
> Christophe
>> regards
>> Julien
>> On 24 Feb 2010, at 02:03, Eric Nutsch wrote:
>>> Hi,
>>> Has anyone successfully gotten an extruded boundary layer to interface
>>> with a mesh?
>>> Thanks,
>>> Eric Nutsch
>>> _______________________________________________
>>> gmsh mailing list
>>> gmsh at geuz.org
>>> http://www.geuz.org/mailman/listinfo/gmsh
>> Julien Hoessler
>> PhD Student
>> Department of Aeronautics
>> Imperial College London
>> Phone: +44 (0) 20759 45042
>> Email: julien.hoessler06 at imperial.ac.uk
>> _______________________________________________
>> gmsh mailing list
>> gmsh at geuz.org
>> http://www.geuz.org/mailman/listinfo/gmsh
> --
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://www.montefiore.ulg.ac.be/~geuzaine