[Gmsh] Is it a Bug in Gmsh? HELP!!!

[Christophe Geuzaine]

zhoujun wrote:
> Dear professor,
>  
> Sorry for posting another problem again. 
> When running Gmsh meshing facility, an eception was thrown out and 
> forced the program to abort.
>  
> It was a very simple geometry only consisting of 12 nodes, 7 surfaces 
> and 1 volume.
> The meshing was runing Gmsh v1.58.0 on WinXP SP2 . Below are info. about 
> the files of cube.geo and .gmsh-errors and stack trace. Please help me 
> to diagnose.

The characteristic length you use would result in a surface mesh of
about 200 million elements... Also, the geometry is wrong: you have
overlapping surfaces. And you should probably use an extruded mesh for
such a thin geometry.

Here is how I would deal with it:

lc = 50;
e = 40; // change to 6 when generating the mesh
nume = 2; // number of elements along the thickness
Point(1) = {-467.5,-467.5,-e/2,lc};
Point(2) = {-467.5,467.5,-e/2,lc};
Point(3) = {467.5,467.5,-e/2,lc};
Point(4) = {467.5,-467.5,-e/2,lc};
Point(5) = {-20,20,-e/2,lc};
Point(6) = {-20,-20,-e/2,lc};
Point(7) = {20,20,-e/2,lc};
Point(8) = {20,-20,-e/2,lc};
Line(1) = {1,4};
Line(2) = {4,3};
Line(3) = {3,2};
Line(4) = {2,1};
Line(5) = {6,8};
Line(6) = {8,7};
Line(7) = {7,5};
Line(8) = {5,6};
Line Loop(9) = {7,8,5,6};
Plane Surface(10) = {9};
Line Loop(11) = {3,4,1,2};
Plane Surface(12) = {11,9};
Extrude Surface {10, {0.0,0.0,e}}{Layers{nume,1};};
Extrude Surface {12, {0.0,0.0,e}}{Layers{nume,1};};

Take care,

Christophe

-- 
Christophe Geuzaine
Applied and Computational Mathematics, Caltech
geuzaine at acm.caltech.edu - http://geuz.org