[Gmsh] Strange problem with very simple geometry

[Michal Hajek]

Hello, 

I experience a problem with gmsh 2.0. 

If I try to mesh a simple 2D object, gmsh works well up to some
characteristic length factor. With smaller length factor, meshing fails. 

E.g. the following command succeed:
gmsh  -m -2 -o "ctverce.msh" ctverce.geo > 02.log 2>&1
with characteristic length m=0.2;

but the same command (except .log file name)
gmsh  -m -2 -o "ctverce.msh" ctverce.geo > 01.log 2>&1

fails if I replace characteristic length in .geo file for m=0.1;

Please see the attached .geo and .log files...


Can anyone please explain this bahaviour? Is that because something is
wrong with my geometry? Or is it because the meshing algorithm is not
perfect yet?  

Best regards
Michal
-------------- next part --------------
Info    : 'gmsh -m -2 -o ctverce01.msh ctverce.geo ' started on Fri Feb  9 08:21:54 2007
Info    : Reading 'ctverce.geo'
Info    : Read 'ctverce.geo'
Info    : Meshing 1D...
Info    : Meshing curve 1
Info    : Meshing curve 2
Info    : Meshing curve 3
Info    : Meshing curve 4
Info    : Meshing curve 5
Info    : Meshing curve 6
Info    : Meshing curve 7
Info    : Meshing curve 8
Info    : Meshing curve 9
Info    : Meshing curve 10
Info    : Meshing curve 11
Info    : Meshing curve 12
Info    : Meshing curve 13
Info    : Meshing curve 14
Info    : Meshing curve 15
Info    : Meshing curve 16
Info    : Meshing curve 17
Info    : Meshing curve 18
Info    : Meshing curve 19
Info    : Meshing curve 20
Info    : Mesh 1D complete (0.004001 s)
Info    : Mesh
Info    : Meshing 2D...
Info    : Meshing surface 1 (Plane)
Error   : 3 identical points in Qtest
Error   : 3 identical points in Qtest
Error   : 3 identical points in Qtest
Info    :  edge 1482 1483 has to be recovered
Error   : Unable to recover an edge 146.398 0 && 146.498 0 (1463/*d)
Error   : Face not meshed
Info    : Meshing surface 2 (Plane)
Info    : Meshing surface 3 (Plane)
Info    : Meshing surface 4 (Plane)
Info    : Meshing surface 5 (Plane)
Info    : Mesh 2D complete (0.512032 s)
Info    : Mesh
Info    : 5560 vertices 7715 elements
Info    : Writing 'ctverce01.msh'
Info    : Wrote 'ctverce01.msh'
-------------- next part --------------
Info    : 'gmsh -m -2 -o ctverce01.msh ctverce.geo ' started on Fri Feb  9 08:22:25 2007
Info    : Reading 'ctverce.geo'
Info    : Read 'ctverce.geo'
Info    : Meshing 1D...
Info    : Meshing curve 1
Info    : Meshing curve 2
Info    : Meshing curve 3
Info    : Meshing curve 4
Info    : Meshing curve 5
Info    : Meshing curve 6
Info    : Meshing curve 7
Info    : Meshing curve 8
Info    : Meshing curve 9
Info    : Meshing curve 10
Info    : Meshing curve 11
Info    : Meshing curve 12
Info    : Meshing curve 13
Info    : Meshing curve 14
Info    : Meshing curve 15
Info    : Meshing curve 16
Info    : Meshing curve 17
Info    : Meshing curve 18
Info    : Meshing curve 19
Info    : Meshing curve 20
Info    : Mesh 1D complete (0 s)
Info    : Mesh
Info    : Meshing 2D...
Info    : Meshing surface 1 (Plane)
Info    : Meshing surface 2 (Plane)
Info    : Meshing surface 3 (Plane)
Info    : Meshing surface 4 (Plane)
Info    : Meshing surface 5 (Plane)
Info    : Mesh 2D complete (47.683 s)
Info    : Mesh
Info    : 98891 vertices 197928 elements
Info    : Writing 'ctverce01.msh'
Info    : Wrote 'ctverce01.msh'
-------------- next part --------------
// Obdelnikovy vzorek, ctvercove kontakty 
// jednoduchy model

m=0.2;

delka=150;
sirka=20;

sirkak=2;

rohx1=1;
rohy1=1;

rohx2=delka-sirkak-1;
rohy2=1;

rohx3=delka-sirkak-1;
rohy3=sirka-sirkak-1;

rohx4=1;
rohy4=sirka-sirkak-1;


// Vzorek
Point(1)= {0,0,0,m};
Point(2)= {delka,0,0,m};
Point(3)= {delka,sirka,0,m};
Point(4)= {0,sirka,0,m};

Line(1)= {1,2};
Line(2)= {2,3};
Line(3)= {3,4};
Line(4)= {4,1};

Line Loop(1)={1,2,3,4};

//////////////////////////////////
// Kontakt 1

Point(5)= {rohx1,rohy1,0,m};
Point(6)= {rohx1+sirkak,rohy1,0,m};
Point(7)= {rohx1+sirkak,rohy1+sirkak,0,m};
Point(8)= {rohx1,rohy1+sirkak,0,m};

Line(5)= {5,6};
Line(6)= {6,7};
Line(7)= {7,8};
Line(8)= {8,5};

Line Loop(2)={5,6,7,8};
Plane Surface(2)={2};

////////////////////////////////////
//// Kontakt 2

Point(9)= {rohx2,rohy2,0,m};
Point(10)= {rohx2+sirkak,rohy2,0,m};
Point(11)= {rohx2+sirkak,rohy2+sirkak,0,m};
Point(12)= {rohx2,rohy2+sirkak,0,m};

Line(9)= {9,10};
Line(10)= {10,11};
Line(11)= {11,12};
Line(12)= {12,9};

Line Loop(3)={9,10,11,12};
Plane Surface(3)={3};

////////////////////////////////////
// Kontakt 3

Point(13)= {rohx3,rohy3,0,m};
Point(14)= {rohx3+sirkak,rohy3,0,m};
Point(15)= {rohx3+sirkak,rohy3+sirkak,0,m};
Point(16)= {rohx3,rohy3+sirkak,0,m};

Line(13)= {13,14};
Line(14)= {14,15};
Line(15)= {15,16};
Line(16)= {16,13};

Line Loop(4)={13,14,15,16};
Plane Surface(4)={4};

////////////////////////////////////
//// Kontakt 4

Point(17)= {rohx4,rohy4,0,m};
Point(18)= {rohx4+sirkak,rohy4,0,m};
Point(19)= {rohx4+sirkak,rohy4+sirkak,0,m};
Point(20)= {rohx4,rohy4+sirkak,0,m};

Line(17)= {17,18};
Line(18)= {18,19};
Line(19)= {19,20};
Line(20)= {20,17};

Line Loop(5)={17,18,19,20};
Plane Surface(5)={5};
Plane Surface(1)={1,2,3,4,5};
Coherence;

Physical Surface (1001) = {2};
Physical Surface (1002) = {3};
Physical Surface (1003) = {4};
Physical Surface (1004) = {5};

Physical Surface (1000) = {1};