[Gmsh] Problems Extruding a structured 2D mesh - transfinite OK on 2D, fails in 3D

[jan at kanoefabrik.com]

I have made a 2D mesh consisting of 24 transfinite surfaces (structured
grid). It meshes perfectly when I click on 2D on the gmsh GUI.

However, when I add the command to extrude (1 layer) the 2D mesh to a flat
3D mesh for use in OpenFOAM, the first nine surfaces and the last surface
are meshed in a structured way (extruded properly), but from surface 10-23,
the 3D transfinite extrusin fails and the structured transfinite grids are
replaced by unstructured meshes.

This is my extrusion command:

**********
Extrude {0,0,0.01} 
{
Surface{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24};
Layers{1}; 
Recombine; 
}
**********

All 24 surfaces are created the same way with identical n0menclature such as
for surface 23:

**********
// Upstream upper wake region - SURFACE 23
Line(80) = {17,33};
Line(81) = {33,34};
Line(82) = {34,18};
Circle(83) = {18, 201, 17};
Transfinite Line {80}  = N80 Using Progression B80;
Transfinite Line {81}  = N81 Using Progression B81;
Transfinite Line {-82} = N82 Using Progression B82;
Transfinite Line {83}  = N83 Using Progression B83;
Line Loop(23) = {80, 81, 82, 83};
Plane Surface(23) = {23};
Transfinite Surface {23} = {17,33,34,18};
Recombine Surface {23};
**********

One point I should make is that some lines share points with other lines and
some lines lie on top of other lines using the same points to define them.
I did this to ensure that the transfinite interpolation on the surfaces that
are separated by these lines is unique for each surface.

I cannot include the entire grid since it is of a confidential nature; can
anyone shed light onto this problem with this limited information?

Thank you!

Dr. Johannes N. Theron
Proprietor
KanoeFabrik
4 Le Roux St.
De Rust, 6650
South Africa
+27 (79) 166-0742
www.kanoefabrik.com
jan at kanoefabrik.com
http://www.facebook.com/people/Kanoe-Fabrik/100001483291810





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