Discussion:
[Gmsh] Problem extruding 2D mesh
Philipp Hein
2015-02-11 11:28:44 UTC
Permalink
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.

Thanks a lot and many greetings,

Philipp
--
Philipp Hein, M.Sc.Eng.

Department Umweltinformatik
Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
Permoserstraße 15 I 04318 Leipzig
Tel.: +49 341 235 - 1804
Fax: +49 341 235 - 1939
Email: ***@ufz.de
WWW: http://www.ufz.de

Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
Sitz der Gesellschaft: Leipzig
Registergericht: Amtsgericht Leipzig
Handelsregister Nr. B 4703
Vorsitzender des Aufsichtsrats: MinR Wilfried Kraus
Wissenschaftlicher Geschäftsführer: Prof. Dr. Georg Teutsch
Administrativer Geschäftsführerin: Dr. Heike Graßmann
Christophe Geuzaine
2015-02-11 15:34:19 UTC
Permalink
Post by Philipp Hein
Hello,
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.
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.
Post by Philipp Hein
Thanks a lot and many greetings,
Philipp
--
Philipp Hein, M.Sc.Eng.
Department Umweltinformatik
Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
Permoserstraße 15 I 04318 Leipzig
Tel.: +49 341 235 - 1804
Fax: +49 341 235 - 1939
WWW: http://www.ufz.de
Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
Sitz der Gesellschaft: Leipzig
Registergericht: Amtsgericht Leipzig
Handelsregister Nr. B 4703
Vorsitzender des Aufsichtsrats: MinR Wilfried Kraus
Wissenschaftlicher Geschäftsführer: Prof. Dr. Georg Teutsch
Administrativer Geschäftsführerin: Dr. Heike Graßmann
_______________________________________________
gmsh mailing list
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
Mikhail Artemyev
2015-02-11 15:48:03 UTC
Permalink
Hi Philipp,

This problem has been discussed just recently
http://www.geuz.org/pipermail/gmsh/2015/009492.html

Best regards,
Mikhail
Post by Philipp Hein
Hello,
i have a problem in creating my desired mesh for a cube. This is what i
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.
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.
Thanks a lot and many greetings,
Philipp
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