[Gmsh] Defining Physical Surface

[Tom Peachey]

Thanks for that Christophe. Yes I have seen that already, but it does not
tell me which lines are labelled 2, 3 etc. My current solution is to take
the Ingram gmsh, where the extrusion of the airfoil  has been identified,
presumably using the GUI, and replace the airfoil coordinates by my new
values. I just hope that changing the number of nodes in the airfoil curve
will not change the index. Short of reading the source code this is not
documented?

Tom

On Fri, 8 Feb 2019 at 17:59, Christophe Geuzaine <cgeuzaine at uliege.be>
wrote:

>
>
> > On 1 Dec 2018, at 12:46, Tom Peachey <tcp.free at gmail.com> wrote:
> >
> >
> > I am planning to run OpenFoam batch jobs, airfoil simulations, using
> gmsh for the meshing. For this I need to automate the creation of .geo
> files. It’s straightforward, following the Ingram tutorial
> > https://community.dur.ac.uk/g.l.ingram/download/gmshtutorial2012.pdf
> >  until the final stage where one defines the “Physical Surfaces”
> > Physical Surface("back") = {1027};
> > presumably  a surface created by the previous “Extrude” command. As
> Ingram says: “Finding the number associated with a particular surface is a
> bit of a pain.” It seems he uses the gmsh GUI which is not available in my
> automated scenario.
> >
> > The Octave code by César A. Vecchio Toloy gives some more detail:
> > fprintf (fid, 'j5[] = Extrude {0,0,%.10g}
> {Surface{5};Layers{1};Recombine;};\n', cuerda/10);
> > fprintf (fid, 'j6[] = Extrude {0,0,%.10g}
> {Surface{6};Layers{1};Recombine;};\n', cuerda/10);
> > followed by
> > fprintf (fid, 'Physical Surface("inlet") = {j5[5],j6[5]};\n');
> > But again it is not clear how to choose the correct components of j5 and
> j6.
>
> Extrude returns the list of generated entities: the “top” of the extruded
> entity at index 0 and the extruded entity at index 1, followed by the
> “sides” of the extruded entity at indices 2, 3, etc.
>
> http://gmsh.info/dev/doc/texinfo/gmsh.html#Extrusions
>
> Christophe
>
>
> >
> > Any help greatly appreciated.
> > _______________________________________________
> > gmsh mailing list
> > gmsh at onelab.info
> > http://onelab.info/mailman/listinfo/gmsh
>
> —
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://www.montefiore.ulg.ac.be/~geuzaine
>
>
>
>
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