# [Gmsh] Problem extruding 2D mesh

Philipp Hein philipp.hein at ufz.de
Wed Feb 11 12:28:44 CET 2015

```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
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