[Gmsh] Bug in gmsh

[Durufle marc]

I think it is minor, because i have this bug only by
specifying lc equal to 0.55 ! Here the geo file used.

lc = 0.55;
r = 2.0;
e = 0.8;
rb = r+e;
teta = 15.0*Pi/180.0;
d = 1.0;
L = r/Sin(teta);
L2 = (rb+d)/Sin(teta);
rc = rb+d;
// generatrice
Point(1) = {0, L, 0, lc};
Point(2) = {r*Cos(teta), r*Sin(teta), 0, lc};
Point(3) = {0, -r, 0, lc};
Point(4) = {0, 0, 0, lc};
Point(5) = {0, -rb, 0,lc};
Point(6) = {rb*Cos(teta), rb*Sin(teta), 0,lc};
Point(7) = {e*Cos(teta), L+e*Sin(teta), 0, lc};
Point(8) = {0, L+e, 0, lc};
Point(9) = {0, L2, 0, lc};
Point(10) = {rc*Cos(teta), rc*Sin(teta), 0, lc};
Point(11) = {0, -rc, 0, lc};

Line(1) = {6, 7};
Circle(2) = {7, 1, 8};
Line(3) = {8, 1};
Line(4) = {2, 1};
Circle(5) = {3, 4, 2};
Line(6) = {3, 5};
Circle(7) = {5, 4, 6};
Line(8) = {10,9};
Line(9) = {9,8};
Line(10) = {5,11};
Circle(11) = {11,4,10};

Line Loop(1) = {1, 2, 3, -4, -5, 6, 7};
Line Loop(2) = {8, 9, -2, -1, -7, 10, 11};
Plane Surface(1) = {1};
Plane Surface(2) = {2};
Extrude Surface {1, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};
Extrude Surface {38, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};
Extrude Surface {65, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};
Extrude Surface {2, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};
Extrude Surface {118, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};
Extrude Surface {145, {0.0,1.0,0.0}, {0.0,0.0,0.0},
2*Pi/3};

Physical Surface(4) = {23,50,77};
Physical Surface(5) = {26,53,80};
Physical Surface(1) = {30,57,84};
Physical Surface(2) = {33,60,87};
Physical Surface(6) = {37,64,91};
Physical Surface(3) = {102,129,156};
Physical Surface(7) = {117,144,171};

Physical Volume(2) = {1, 2, 3};
Physical Volume(1) = {4, 5, 6};

I have another problem, in truth. I find that the
coarse meshes (by example for this mesh, you choose lc
= 1.0) are not very sympathic :-( When i use straight
tetrahedra for a P1 computation, it is ok. But, in
fact, i prefer to use P4 finite element with curved
tetrahedra. By doing this, i have degenerated elements
(the jacobian is negative on some elements) if the
mesh is too coarse. The only thing I can do is to
refine the mesh. But refining mesh provides sometimes
lots of degrees of freedom :-(


This geo file is a cone sphere geometry coated by a
thin layer. If i take a thickness smaller (e = 0.2
instead of e = 0.8), it is difficult to avoid
degenerated elements, unless I put lots of
tetrahedra...






	

	
		
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