[Gmsh] mesh a hemisphere using hexahedral

Wed Nov 2 14:25:45 CET 2011

Hi Margarita,

As all your surfaces have four sides and your volumes six sides, 
you can let Gmsh do most of the work for you:  no need of indicating the loop of corners/surfaces.

I guess you had given a bad loop or forgotten to Recombine one surfaces.
See the attached corrected file.

Regards,
Ruth  

--
Dr. Ir. Ruth V. Sabariego
University of Liege, Electrical Engineering & Computer Science, 
Applied & Computational Electromagnetics (ACE),
phone: +32-4-3663737 - fax: +32-4-3662910 - http://ace.montefiore.ulg.ac.be/

On 02 Nov 2011, at 13:35, Margarita Satraki wrote:

> Hi,
> 
> I'm trying to mesh a hemisphere using only hexahedral and I followed the logic behind the code given here:
> http://geuz.org/pipermail/gmsh/2005/001609.html
> 
> I'm probably doing something wrong with the Transfinite function and I get errors such as:
> "Cannot tetrahedralize volume with quadrangles on boundary"
> But what I want is the software to hexahedralize. Can you spot the problem with the code?
> 
> Many thanks!
> 
> Margarita
> 
> ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> 
> l = 1;
> r1 = 0.5;
> r2 = 1;
> n = 10;
> r3=1.224744871391589;
> 
> // interior cube
> Point(1) = {0,0,0,l};
> Point(2) = {r1,r1,-r1,l};
> Point(3) = {-r1,r1,-r1,l};
> Point(4) = {-r1,-r1,-r1,l};
> Point(5) = {r1,-r1,-r1,l};
> Line(1) = {2,3};
> Line(2) = {3,4};
> Line(3) = {4,5};
> Line(4) = {5,2};
> Transfinite Line{1:4} = n;
> Line Loop(5) = {4,1,2,3};
> Plane Surface(6) = {5};
> Transfinite Surface{6} = {2,3,4,5};
> Recombine Surface{6};
> Extrude Surface {6, {0.0,0.0,r1}};
> 
> // force transfinite grid in interior cube
> Transfinite Line {3,22,11,13,8,4,14,9,1,18,10,2} = n;
> Transfinite Surface {6} = {4,5,2,3};
> Transfinite Surface {15} = {5,6,7,2};
> Transfinite Surface {19} = {11,7,2,3};
> Transfinite Surface {23} = {4,15,11,3};
> Transfinite Surface {27} = {15,6,5,4};
> Transfinite Surface {28} = {15,6,7,11};
> Recombine Surface{6,15,19,23,27,28};
> Transfinite Volume{1} = {4,5,2,3,15,6,7,11};
> 
> // exterior shell
> Point(102) = {r2,-r2,-r2,l};
> Point(103) = {-r2,-r2,-r2,l};
> Point(104) = {-r3,-r3,-0,l};
> Point(105) = {r3,-r3,-0,l};
> Circle(29) = {103,1,102};
> Circle(30) = {102,1,105};
> Circle(31) = {105,1,104};
> Circle(32) = {104,1,103};
> Line Loop(33) = {29,30,31,32};
> Ruled Surface(45) = {33};
> Rotate { {0,0,1},{0,0,0}, Pi/2 } { Duplicata{ Surface{45}; } }
> Rotate { {0,0,1},{0,0,0}, Pi } { Duplicata{ Surface{45}; } }
> Rotate { {0,0,1},{0,0,0}, 3*Pi/2 } { Duplicata{ Surface{45}; } }
> 
> 
> 
> Line Loop(58) = {51, 55, 29, 47};
> Ruled Surface(59) = {58};
> Line(60) = {11, 121};
> Line(61) = {116, 3};
> Line(62) = {15, 104};
> Line(63) = {103, 4};
> Line(64) = {6, 105};
> Line(65) = {102, 5};
> Line(66) = {7, 113};
> Line(67) = {108, 2};
> Line Loop(68) = {61, 18, 60, -52};
> Plane Surface(69) = {68};
> Line Loop(70) = {67, 14, 66, -48};
> Plane Surface(71) = {70};
> Line Loop(72) = {65, 13, 64, -30};
> Plane Surface(73) = {72};
> Line Loop(74) = {22, 62, 32, 63};
> Plane Surface(75) = {74};
> Line Loop(76) = {10, 62, 57, -60};
> Plane Surface(77) = {76};
> Line Loop(78) = {9, 60, 53, -66};
> Plane Surface(79) = {78};
> Line Loop(80) = {8, 66, 49, -64};
> Plane Surface(81) = {80};
> Line Loop(82) = {4, -67, -47, 65};
> Plane Surface(83) = {82};
> Line Loop(84) = {29, 65, -3, -63};
> Plane Surface(85) = {84};
> Line Loop(86) = {2, -63, -55, 61};
> Plane Surface(87) = {86};
> Line Loop(88) = {51, 61, -1, -67};
> Plane Surface(89) = {88};
> Line Loop(91) = {11, 64, 31, -62};
> Plane Surface(92) = {91};
> 
> Transfinite Line {49,31,32,53,8,9,10,11,47,51,57,29,55,30,48,52,32,65,64,63,62,60,61,66,67} = n;
> Transfinite Surface {77} = {15,11,121,104};
> Transfinite Surface {75} = {103,4,15,104};
> Transfinite Surface {69} = {3,11,121,116};
> //Transfinite Surface {23} = {};
> Transfinite Surface {87} = {103,116,4,3};
> Transfinite Surface {54} = {103,116,121,104};
> Recombine Surface{77,75,69,23,87,54};
> Surface Loop(99) = {77, 54, 75, 69, 23, 87};
> Volume(100) = {99};
> 
> Transfinite Surface {79} = {11,7,113,121};
> //Transfinite Surface {69} = {3,11,121,116};
> Transfinite Surface {71} = {2,108,113,7};
> Transfinite Surface {50} = {116,108,113,121};
> //Transfinite Surface {19} = {11,7,2,3};
> Transfinite Surface {89} = {2,3,116,108};
> Recombine Surface{79,69,71,50,19,89};
> Surface Loop(93) = {50, 79, 89, 19, 71, 69};
> Volume(94) = {93};
> 
> Transfinite Surface {81} = {7,6,105,113};
> //Transfinite Surface {71} = {2,108,113,7};
> Transfinite Surface {73} = {5,6,105,102};
> Transfinite Surface {83} = {2,5,102,108};
> Transfinite Surface {46} = {102,105,113,108};
> //Transfinite Surface {15} = {};
> Recombine Surface{81,71,73,83,46,15};
> Surface Loop(95) = {81, 46, 71, 73, 15, 83};
> Volume(96) = {95};
> 
> Transfinite Surface {92} = {6,15,105,104};
> //Transfinite Surface {27} = {};
> Transfinite Surface {45} = {105,104,103,102};
> //Transfinite Surface {73} = {};
> //Transfinite Surface {75} = {};
> Transfinite Surface {85} = {4,5,102,103};
> Recombine Surface{92,27,45,73,75,85};
> Surface Loop(97) = {92, 45, 73, 75, 85, 27};
> Volume(98) = {97};
> 
> //Transfinite Surface {89} = {};
> //Transfinite Surface {87} = {};
> //Transfinite Surface {83} = {};
> //Transfinite Surface {6} = {};
> Transfinite Surface {59} = {102,108,116,103};
> //Transfinite Surface {85} = {};
> Recombine Surface{89,87,83,6,59,85};
> Surface Loop(101) = {59, 85, 83, 89, 87, 6};
> Volume(102) = {101};
> 
> Transfinite Volume{100} = {15,11,3,4,121,104,103,116};
> Transfinite Volume{94} = {2,3,11,7,113,121,116,108};
> Transfinite Volume{96} = {2,5,6,7,102,105,108,113};
> Transfinite Volume{98} = {4,5,6,15,102,103,104,105};
> Transfinite Volume{102} = {2,3,4,5,102,108,103,116};
> Physical Volume(1) = {1, 94:102:2};
> Mesh 3;
> _______________________________________________
> gmsh mailing list
> gmsh at geuz.org
> http://www.geuz.org/mailman/listinfo/gmsh

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