[Gmsh] GMSH is not extruding a surface which has been defined as an extrusion of a line

[Christophe Geuzaine]

Hi Paolo,

Indeed, Gmsh can currently not extrude "boundary layer" surfaces.

Your best bet for now is to directly create a "boundary layer" volume (cf. the example on the wiki).

Christophe

On 29 Jan 2013, at 14:49, Paolo Tricerri <paolotricerri at gmail.com> wrote:

> Dear all,
> 
> I have this simple problem which I cannot fix. I am trying to define a volume as the extrusion of a surface which was defined as the extrusion of a line. Gmsh is not able to mesh the 3D volume.
> 
> The code which does not work is the following:
> 
> lc = 0.1;
> h = 0.1;
> R= 0.50;
> L = 10.0;
> 
> // ############# POINTS ##############
> //Base
> Point(0) = {0, 0, 0, lc};
> Point(1) = {R, 0, 0, lc};
> Point(2) = {0, R, 0, lc};
> Point(3) = {-R, 0, 0, lc};
> Point(4) = {0, -R, 0, lc};
> 
> Circle(1) = {1,0,2};
> Circle(2) = {2,0,3};
> Circle(3) = {3,0,4};
> Circle(4) = {4,0,1};
> 
> Transfinite Line{1,2,3,4}=27;
> Line Loop(100)={1,2,3,4};
> 
> nb_layers = 5;
> nE = 20;
>  
> out[] = Extrude{Line{1};Layers{nb_layers,-0.1};Using Index[1];};
> 
> // //Extruding the surfaces
> extV[] = Extrude{0,0,L}{Surface{out[1]}; Layers{nE}; }; 
> 
> Physical Volume(1)={extV[1]};
> 
> It looks ok to me and I do not see the problem. What is weird is that I have used a similar code (in another script) and it works fine. Here there is the second find:
> 
> lc = 0.1;
> h = 0.1;
> R= 0.50;
> L = 20.0;
> 
> // ############# POINTS ##############
> //Base
> Point(0) = {0, 0, 0, lc};
> Point(1) = {R, 0, 0, lc};
> Point(2) = {0, R, 0, lc};
> 
> //############### LINES ##############
> //Base`
> Circle(1) = {1,0,2};
> Transfinite Line{1}=45;
> 
> nb_layers = 120;
> out[] = Extrude{0, 0, L}{Line{1};Layers{nb_layers};};
> 
> Physical Surface(200)={out[1]};
> 
> out2[] = Extrude{Surface{out[1]};Layers{10,0.1};};
> 
> Physical Volume(1) = {out2[1]}
> 
> In the second script I am doing the meshing process in the other way around but it should not change because the Extrude commands are the same.
> 
> What could be the problem?
> 
> Many thanks,
> 
> Paolo Tricerri
> _______________________________________________
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> gmsh at geuz.org
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine