[Gmsh] hybrid prism/tetrahedrons mesh

Wed Sep 30 17:11:51 CEST 2009

Hi David,
With the updated version of gmsh and using the frontal3d algorithm,  
everything works fine.
Thanks for your help
regards
Julien
On 30 Sep 2009, at 14:57, David Colignon wrote:

>
> julien hoessler wrote:
>> Hi David,
>> Thanks for replying.
>> Here is a screenshot, clipping the tetrahedrons, and you can see a
>> single edge along the wrong diagonal at the bottom:
>>
>> ------------------------------------------------------------------------
>>
>>
>>
>> I was using the wrong algorithm I guess, as it does not happen with
>> netgen. It also happens with the frontal algo though. May it be due  
>> to
>> the smoothing steps (-smooth 10000) ?
>
> Which Gmsh version are you using ? The naming of the 2D and 3D  
> meshing algorithm in the GUI has changed
>  several times (...)
> I was using version 2.4.1 ( and it is the same in 2.4.2 ).
> In 3D, Delaunay=Tegen , Frontal = Netgen
>
> You can specify the algo in the .geo file:
> Mesh.Algorithm = 1; // 2D mesh algorithm (1=MeshAdapt, 5=Delaunay,  
> 6=Frontal)
> Mesh.Algorithm3D = 4; // 3D mesh algorithm (1=Delaunay, 4=Frontal)
>
>
> Dave
>
>
>> Best regards
>> Julien
>> On 30 Sep 2009, at 13:08, David Colignon wrote:
>>
>>>
>>> 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
>>> Sart-Tilman B28
>>> Université de Liège
>>> 4000 Liège - BELGIQUE
>>> Tél: +32 (0)4 366 37 32
>>> Fax: +32 (0)4 366 29 10
>>> WWW:    http://hpc.montefiore.ulg.ac.be/
>>> Agenda:
>>> http://www.google.com/calendar/embed?src=david.colignon%40gmail.com
>>>
>>>
>>>
>>>>
>>>> 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};
>>>> _______________________________________________
>>>> gmsh mailing list
>>>> gmsh at geuz.org
>>>> http://www.geuz.org/mailman/listinfo/gmsh
>>>
>>
>