[Gmsh] Problem extruding 2D mesh

Christophe Geuzaine cgeuzaine at ulg.ac.be
Wed Feb 11 16:34:19 CET 2015


> On 11 Feb 2015, at 12:28, Philipp Hein <philipp.hein at ufz.de> wrote:
> 
> Hello,
> 
> i have a problem in creating my desired mesh for a cube. This is what i want to do:
> 1. Creating a plane surface
> 2. Inserting some points on this surface
> 3. Creating a surface mesh where the points from step 2 are considered
> 4. Extruding the surface mesh to a 3d-prism-mesh with several layers
> 
> For me it is important that the surface mesh is extruded as a structured mesh, because i need nodes vertical under the points inserted in step 2 for line elements later on.
> This is the script for my test example:
> 
>    sl = 100.0; // Geometry parameters
>    a = sl/2.0;
>    Point (0) = {0, 0, 0, 1}; // Point to be included
>    Point (1) = {-a, -a, 0, 10}; // Corner points
>    Point (2) = {a, -a, 0, 10};
>    Point (3) = {a, a, 0, 10};
>    Point (4) = {-a, a, 0, 10};
>    Line (1) = {1,2}; // Lines forming the rectangle
>    Line (2) = {2,3};
>    Line (3) = {3,4};
>    Line (4) = {4,1};
>    Line Loop (5) = {1, 2, 3, 4};
>    Plane Surface (0) = {5}; // Creating the plane surface
>    Point {0} In Surface {0}; // Forcing my important point to be on the surface mesh
>    Extrude {0, 0, 10} { Surface {0}; Layers {1}; Recombine; } // Extruding
>    Mesh 3; // Meshing
> 
> This script creates a mesh and extrudes the surface mesh except the elements that are connected to point 0. GMSH says
>    Error   : Could not find extruded vertex (0, 0, 10) in surface 27
> and then repeatedly
>    Info    : Linear search for (0, 0, 0)
>    Error   : Could not find extruded vertex (0, 0, 0)
> 
> I am not sure if this is a bug or if the extrude-feature doesn't work like i expect or if there is another way to achieve my desired mesh.

We do not yet support extrusion of embedded ("Point ... In Surface ...") points. You will have to subdivide the surface to extrude so that the point is the end-point of a curve on its boundary.



> 
> Thanks a lot and many greetings,
> 
> Philipp
> 
> 
> -- 
> Philipp Hein, M.Sc.Eng.
> 
> Department Umweltinformatik
> Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
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> Tel.: +49 341 235 - 1804
> Fax: +49 341 235 - 1939
> Email: philipp.hein at ufz.de
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> 
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> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine







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