Danny Holstein wrote:
All;
Let me try again. How difficult would it be to modify GMSH to create a "Periodic Plane"?
Either a boolean switch could be set while doing a translate/rotate or the 2 planes could be
grouped as a physical entity, which would be 2-D meshed once with the mesh elements copied to it's
"periodic" brother.
Certainly, many problems have 180 degree rotational symmetry, and many RF
devices (such as helix and coupled cavity TWTs and klystrons) have axial
symmetry, magnetrons/CFAs have rotational symmetry to the vanes. Mechanical
structures with spokes would be greatly simplified with this symmetry.
It seems the switch used with a new "Periodic Plane" would be best, the
translation matrix could be stored on generation and used immediately after mesh
generation.
Hi Danny - Here's a little example on how you could do this using
extruded meshes.
Thoughts?
...Dan
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Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
Point(1) = {0.2, 0.8, 0,0.005};
Point(2) = {0.6, 0.8, 0, 0.05};
Point(3) = {0.6, 0.6, 0, 0.05};
Point(4) = {0.5, 0.6, 0, 0.05};
Point(5) = {0.5, 0.5, 0, 0.05};
Point(6) = {0.6, 0.5, 0, 0.05};
Point(7) = {0.6, 0.3, 0, 0.2};
Point(8) = {0.2, 0.3, 0, 0.2};
Line(1) = {2, 1};
Line(2) = {1, 8};
Line(3) = {8, 7};
Line(4) = {7, 6};
Line(5) = {6, 5};
Line(6) = {5, 4};
Line(7) = {4, 3};
Line(8) = {3, 2};
Line Loop(9) = {8, 1, 2, 3, 4, 5, 6, 7};
Plane Surface(10) = {9};
// Nice little hack to generate periodic surface meshes on
// non-extrudable geometries: first extrude the surface, then delete
// all the "middle" entities :-)
Extrude {{0, 1, 0}, {0, 0, 0}, Pi/3} {
Surface{10}; Layers{1};
}
Delete {
Volume{1};
Surface{27, 51, 23, 47, 43, 31, 35, 39};
Line{26, 22, 46, 21, 42, 38, 30, 34};
}
// Add a funky looking volume in between
Point(100) = {0.25, 0.3, -0.2, 0.2};
Point(101) = {0.25, 0.5, -0.2, 0.2};
Point(102) = {0.25, 0.6, -0.2, 0.2};
Point(103) = {0.25, 0.8, -0.2, 0.2};
Line(53) = {22, 100};
Line(54) = {100, 7};
Line(55) = {30, 101};
Line(56) = {101, 26};
Line(57) = {34, 102};
Line(58) = {102, 9};
Line(59) = {10, 103};
Line(60) = {6, 101};
Line(61) = {101, 5};
Line(62) = {102, 4};
Line(63) = {3, 102};
Line(64) = {2, 103};
Line(65) = {1, 14};
Line(66) = {8, 18};
Line(67) = {103, 102};
Line(68) = {102, 101};
Line(69) = {101, 100};
Line Loop(70) = {54, 4, 60, 69};
Plane Surface(71) = {70};
Line Loop(72) = {5, -61, -60};
Plane Surface(73) = {72};
Line Loop(74) = {6, -62, 68, 61};
Plane Surface(75) = {74};
Line Loop(76) = {62, 7, 63};
Plane Surface(77) = {76};
Line Loop(78) = {8, 64, 67, -63};
Plane Surface(79) = {78};
Line Loop(80) = {59, 67, 58, 12};
Plane Surface(81) = {80};
Line Loop(82) = {58, -19, 57};
Plane Surface(83) = {82};
Line Loop(84) = {18, 57, 68, -55};
Plane Surface(85) = {84};
Line Loop(86) = {55, 56, 17};
Plane Surface(87) = {86};
Line Loop(88) = {16, -56, 69, -53};
Plane Surface(89) = {88};
Line Loop(90) = {65, -13, 59, -64, 1};
Plane Surface(91) = {90};
Line Loop(92) = {3, -54, -53, -15, -66};
Plane Surface(93) = {92};
Line Loop(94) = {14, -66, -2, 65};
Plane Surface(95) = {94};
Surface Loop(96) = {91, 95, 52, 81, 79, 10, 93, 71, 73, 75, 77, 85, 83, 87, 89};
Volume(97) = {96};
Physical Surface("Periodic faces") = {10, 52};
Physical Volume("Volume in between") = {97};
// Use the frontal algo to make sure that the periodic surface mesh is
// not modified when meshing the volume
Mesh.Algorithm3D = 4;
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