[Gmsh] hybrid prism/tetrahedrons mesh

Wed Sep 30 14:08:37 CEST 2009

Hoessler, Julien wrote:
> Good afternoon everybody,

Hi Julien,

> I am trying to build an unstructured tetrahedron mesh with a layer of=20
> prisms on one of the delimiting surfaces. I thus extrude and recombine=20
> all the surfacic zones of this wall to generate the layer. But when I=20
> then mesh the rest of the volume with tetrahedrons, I end up with a=20
> few groups of two triangles at the interface that seem to have been=20
> recombined into a quad and splitted along the wrong diagonal (all the=20
> nodes are matching). 

Could you send us a screen capture ?

I have tried to remove the smoothing/optimisation=20
> steps on the netgen/tetgen process, but it doesn't change much. Is=20
> there a way to make the extrusion only after the end of the volumic=20
> mesh of the tetrahedrons regions, 

No

or to avoid modifying the surfacic=20
> meshes? 

you should use the Frontal/Netgen 3D meshing algorithm.

Cheers,

Dave

-- 
David Colignon, Ph.D.
Collaborateur Logistique du F.R.S.-FNRS
CÉCI - Consortium des Équipements de Calcul Intensif
ACE - Applied & Computational Electromagnetics
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Université de Liège
4000 Liège - BELGIQUE
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> 
> Best regards
> Julien Hoessler
> 
> Below is the geo file:
> //*********** PARAMS *************//
> //Domain box
> lx =3D 25;
> ly =3D 25;
> lz =3D 50;
> //High resolution box
> bz1 =3D 15;
> bz2 =3D 30;
> bx1 =3D 5;
> bx2 =3D 0;
> bx3 =3D 10;
> bx4 =3D 2.5;
> bx5 =3D 10;
> by1 =3D 5;
> by2 =3D 7.5;
> by3 =3D 10;
> //buffer box
> dx =3D 2.5;
> dy =3D 2.5;
> dz =3D 2.5;
> ryI =3D 7;
> rb  =3D 1.00;
> rb2 =3D 1.5;
> rdI =3D 5;
> rdO =3D 7.5;
> //*********** POINTS *************//
> //Points domain
> Point(1) =3D {-lx,1,0,rdI};
> Point(2) =3D {lx,1,0,rdI};
> Point(3) =3D {lx,ly,0,rdI};
> Point(4) =3D {-lx,ly,0,rdI};
> Point(5) =3D {lx,1,lz,rdO};
> Point(6) =3D {-lx,1,lz,rdO};
> Point(7) =3D {-lx,ly,lz,rdO};
> Point(8) =3D {lx,ly,lz,rdO};
> //Points high resolution box
> Point(9) =3D {-bx1,1,0,rb};
> Point(10) =3D {bx1,1,0,rb};
> Point(11) =3D {bx2,1,bz1,rb};
> Point(12) =3D {bx3,1,bz1,rb};
> Point(13) =3D {bx4,1,bz2,rb};
> Point(14) =3D {bx5,1,bz2,rb};
> Point(15) =3D {-bx1,by1,0,rb};
> Point(16) =3D {bx1,by1,0,rb};
> Point(17) =3D {bx2,by2,bz1,rb};
> Point(18) =3D {bx3,by2,bz1,rb};
> Point(19) =3D {bx4,by3,bz2,rb};
> Point(20) =3D {bx5,by3,bz2,rb};
> //Points buffer zone
> Point(21) =3D {-bx1-dx,1,0,rb2};
> Point(22) =3D {bx1+dx,1,0,rb2};
> Point(23) =3D {bx2-dx,1,bz1,rb2};
> Point(24) =3D {bx3+dx,1,bz1,rb2};
> Point(25) =3D {bx4-dx,1,bz2+dz,rb2};
> Point(26) =3D {bx5+dx,1,bz2+dz,rb2};
> Point(27) =3D {-bx1-dx,by1+dy,0,rb2};
> Point(28) =3D {bx1+dx,by1+dy,0,rb2};
> Point(29) =3D {bx2-dx,by2+dy,bz1,rb2};
> Point(30) =3D {bx3+dx,by2+dy,bz1,rb2};
> Point(31) =3D {bx4-dx,by3+dy,bz2+dz,rb2};
> Point(32) =3D {bx5+dx,by3+dy,bz2+dz,rb2};
> //*********** LINES *************//
> Line(1) =3D {2,22};
> Line(2) =3D {22,10};
> Line(3) =3D {10,9};
> Line(4) =3D {9,21};
> Line(5) =3D {21,1};
> Line(6) =3D {1,4};
> Line(7) =3D {4,3};
> Line(8) =3D {3,2};
> Line(9) =3D {2,5};
> Line(10) =3D {5,8};
> Line(11) =3D {8,7};
> Line(12) =3D {5,6};
> Line(13) =3D {6,7};
> Line(14) =3D {7,4};
> Line(15) =3D {1,6};
> Line(16) =3D {22,24};
> Line(17) =3D {26,24};
> Line(18) =3D {26,25};
> Line(19) =3D {25,23};
> Line(20) =3D {23,21};
> Line(21) =3D {21,27};
> Line(22) =3D {27,29};
> Line(23) =3D {29,31};
> Line(24) =3D {31,32};
> Line(25) =3D {32,26};
> Line(26) =3D {25,31};
> Line(27) =3D {23,29};
> Line(28) =3D {30,24};
> Line(29) =3D {22,28};
> Line(30) =3D {28,27};
> Line(31) =3D {28,30};
> Line(32) =3D {30,32};
> Line(33) =3D {30,29};
> Line(34) =3D {8,3};
> Line(35) =3D {10,16};
> Line(36) =3D {16,15};
> Line(37) =3D {15,9};
> Line(38) =3D {12,18};
> Line(39) =3D {17,11};
> Line(40) =3D {10,12};
> Line(41) =3D {9,11};
> Line(42) =3D {12,14};
> Line(43) =3D {14,13};
> Line(44) =3D {13,11};
> Line(45) =3D {17,19};
> Line(46) =3D {19,20};
> Line(47) =3D {20,18};
> Line(48) =3D {19,13};
> Line(49) =3D {14,20};
> Line(50) =3D {17,15};
> Line(51) =3D {16,18};
> //*********** SURFACES *************//
> Line Loop(52) =3D {1,16,-17,18,19,20,5,15,-12,-9};
> Plane Surface(53) =3D {52};
> Line Loop(54) =3D {2,40,42,43,44,-41,4,-20,-19,-18,17,-16};
> Plane Surface(55) =3D {54};
> Line Loop(56) =3D {40,42,43,44,-41,-3};
> Plane Surface(57) =3D {56};
> Line Loop(58) =3D {35,36,37,-3};
> Plane Surface(59) =3D {58};
> Line Loop(60) =3D {35,51,-38,-40};
> Plane Surface(61) =3D {60};
> Line Loop(62) =3D {47,-38,42,49};
> Plane Surface(63) =3D {62};
> Line Loop(64) =3D {46,-49,43,-48};
> Plane Surface(65) =3D {64};
> Line Loop(66) =3D {44,-39,45,48};
> Plane Surface(67) =3D {66};
> Line Loop(68) =3D {50,37,41,-39};
> Plane Surface(69) =3D {68};
> Line Loop(70) =3D {2,35,36,37,4,21,-30,-29};
> Plane Surface(71) =3D {70};
> Line Loop(72) =3D {50,-36,51,-47,-46,-45};
> Plane Surface(73) =3D {72};
> Line Loop(74) =3D {20,21,22,-27};
> Plane Surface(75) =3D {74};
> Line Loop(76) =3D {23,-26,19,27};
> Plane Surface(77) =3D {76};
> Line Loop(78) =3D {18,26,24,25};
> Plane Surface(79) =3D {78};
> Line Loop(80) =3D {32,25,17,-28};
> Plane Surface(81) =3D {80};
> Line Loop(82) =3D {31,28,-16,29};
> Plane Surface(83) =3D {82};
> Line Loop(84) =3D {30,22,-33,-31};
> Plane Surface(85) =3D {84};
> Line Loop(86) =3D {32,-24,-23,-33};
> Plane Surface(87) =3D {86};
> Line Loop(88) =3D {6,7,8,1,29,30,-21,5};
> Plane Surface(89) =3D {88};
> Line Loop(90) =3D {14,-6,15,13};
> Plane Surface(91) =3D {90};
> Line Loop(92) =3D {11,-13,-12,10};
> Plane Surface(93) =3D {92};
> Line Loop(94) =3D {10,34,8,9};
> Plane Surface(95) =3D {94};
> Line Loop(96) =3D {34,-7,-14,-11};
> Plane Surface(97) =3D {96};
> //*********** VOLUMES *************//
> Surface Loop(98) =3D {53,89,91,97,95,93,77,87,81,79,83,85,75};
> Volume(99) =3D {98};
> Surface Loop(100) =3D {79,77,87,81,83,85,75,55,71,63,73,69,67,65,61};
> Volume(101) =3D {100};
> Surface Loop(102) =3D {65,73,69,67,61,63,57,59};
> Volume(103) =3D {102};
> //*********** EXTRUSIONS *************//
> outv[]=3D Extrude {0,-1,0}{ Surface{53,55,57}; Layers{2};};
> //*********** B CONDITIONS *************//
> Physical Surface(101) =3D {155,249,217};
> Physical Surface(102) =3D {91,146,154,95,89,71,59,248,172,196,142,118};
> Physical Surface(100) =3D {97};
> Physical Surface(103) =3D {93,150};
> Physical Volume(150) =3D {105,104,103,106,101,99};
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