[Gmsh] 2D isotropic mesh algorithm : bug in node ordering ?

[Bioul Francois]

Mr Geuzaine, 

I use the 2D isotropic mesh algorithm (#1), and I have noted a bug (?)
in the triangle node ordering : nodes describing triangles are numbered
clockwise instead of counter-clockwise (conventionally).

In the attached file "bug.msh", the triangle #27 for example is defined
by the nodes "5 1 22" instead of "5 22 1".

Remark : with the anisotropic algorithms, there are no problems.

Is it possible to correct this node ordering in the 2D isotropic
algorithm?

Thank you very much.

-- 
François Bioul - F.N.R.S. Research Fellow
________________________________________________
Université Catholique de Louvain (UCL)
Center for Systems Eng. and Appl. Mech. (CESAME)
Bâtiment Euler, 4 Avenue G. Lemaitre
B-1348 Louvain-La-Neuve
BELGIUM

Phone : +32 10 47.23.55
Fax.  : +32 10 47.21.80
-------------- next part --------------
Point(1) = {0, 0, 0, 0.25};
Point(2) = {1, 0, 0, 0.25};
Point(3) = {1, 1, 0, 0.25};
Point(4) = {0, 1, 0, 0.25};

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

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

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

Physical Surface (1) = {1};

Mesh.Algorithm=1;
-------------- next part --------------
$NOD
25
1 0 0 0
2 1 0 0
3 1 1 0
4 0 1 0
5 0.3333333333333288 0 0
6 0.6666666666666575 0 0
7 1 0.3333333333333288 0
8 1 0.6666666666666575 0
9 0.6666666666666713 1 0
10 0.3333333333333426 1 0
11 0 0.6666666666666713 0
12 0 0.3333333333333426 0
13 0.5000964525661936 0.5000744489493554 0
14 0.2917652505157438 0.7084463787829387 0
15 0.2917181374310389 0.2917853867778565 0
16 0.708443708717593 0.2917683032273291 0
17 0.7084254545903867 0.708397878340266 0
18 0.5000760433471493 0.1727437969258475 0
19 0.5001092053080949 0.8274291194170477 0
20 0.827453880915579 0.5000883054722366 0
21 0.1727608929451485 0.5001293362897605 0
22 0.1250995048098724 0.1667072975175566 0
23 0.8750996278065628 0.8333907034200734 0
24 0.1250491074292246 0.8333824500351802 0
25 0.8750762533113811 0.1667851039561283 0
$ENDNOD
$ELM
48
1 1 1 1 2 1 5
2 1 1 1 2 5 6
3 1 1 1 2 6 2
4 1 2 2 2 2 7
5 1 2 2 2 7 8
6 1 2 2 2 8 3
7 1 3 3 2 3 9
8 1 3 3 2 9 10
9 1 3 3 2 10 4
10 1 4 4 2 4 11
11 1 4 4 2 11 12
12 1 4 4 2 12 1
13 2 1 1 3 13 14 19
14 2 1 1 3 16 13 20
15 2 1 1 3 13 17 20
16 2 1 1 3 17 13 19
17 2 1 1 3 15 13 18
18 2 1 1 3 14 13 21
19 2 1 1 3 13 16 18
20 2 1 1 3 13 15 21
21 2 1 1 3 6 5 18
22 2 1 1 3 12 11 21
23 2 1 1 3 8 7 20
24 2 1 1 3 4 10 24
25 2 1 1 3 9 3 23
26 2 1 1 3 10 9 19
27 2 1 1 3 5 1 22
28 2 1 1 3 2 6 25
29 2 1 1 3 10 14 24
30 2 1 1 3 17 9 23
31 2 1 1 3 6 16 25
32 2 1 1 3 15 5 22
33 2 1 1 3 15 12 21
34 2 1 1 3 14 10 19
35 2 1 1 3 5 15 18
36 2 1 1 3 16 6 18
37 2 1 1 3 7 16 20
38 2 1 1 3 11 14 21
39 2 1 1 3 9 17 19
40 2 1 1 3 17 8 20
41 2 1 1 3 14 11 24
42 2 1 1 3 12 15 22
43 2 1 1 3 16 7 25
44 2 1 1 3 8 17 23
45 2 1 1 3 11 4 24
46 2 1 1 3 3 8 23
47 2 1 1 3 1 12 22
48 2 1 1 3 7 2 25
$ENDELM