[Gmsh] Extruding surface meshed with unstructured quadrangles.

[Ruth V. Sabariego]

Have you tried this:

Extrude {0, 0, z} {
  Surface{8}; Layers{1} ; Recombine ;
}

Regards,
Ruth


mark starnes wrote:
> Hi everyone,
>
> I have a flat surface, meshed with quadrangles which is extruded normal
> to its plane.  I'd like the through thickness mesh to be ordered, and
> one element thick.  I attempted to generate the mesh by extruding the
> surface, but found I preferred to manually specify the nodes, lines etc.
>
> My question is, is it possible to generate the 3-D mesh?  When I try to
> do so, I get
>
> Error:  Cannot tetrahedralize volume with quadrangles on boundary.
>
> I thought I wanted to 'hexehedralize' the volume, but can't see how to do it.
> Can anyone help?
>
> Best regards,
>
> Mark.
>
> Version: 2.2.7-cvs-20081218
>
> Script follows:
>
> // Gmsh project created on Tue Aug  5 18:29:53 2008
> r0 = 0.025;     // device radius
> r1 = 0.025;     // damping radius
> h  = 0.01;      // duct height
> z = 0.001;      // 3-D thickness
>
> l = 0.01;       // interest wavelength
> // To get 2D quads, a recombine occurs.  This doubles the
> // mesh density, so start with it at half the target.
> cl = 2 * l/10;  // characteristic length:  Set to 10 elements / wavelength
>
>
> // layer 1
> Point(1) = {0,  h/2, 0, cl};
> Point(2) = {r0, h/2, 0, cl};
> Point(3) = {r0, h/2 + r1 - h/2, 0, cl};
> Point(4) = {r0, 0, 0, cl};
> Point(5) = {r0, -h/2 - r1 + h/2, 0, cl};
> Point(6) = {r0, -h/2, 0, cl};
> Point(7) = {0,  -h/2, 0, cl};
>
> // layer 2
> Point(11) = {0,  h/2, z, cl};
> Point(12) = {r0, h/2, z, cl};
> Point(13) = {r0, h/2 + r1 - h/2, z, cl};
> Point(14) = {r0, 0, z, cl};
> Point(15) = {r0, -h/2 - r1 + h/2, z, cl};
> Point(16) = {r0, -h/2, z, cl};
> Point(17) = {0,  -h/2, z, cl};
>
> // layer 1
> Line(1) = {1, 2};
> Line(2) = {2, 3};
> Circle(3) = { 5, 4, 3};
> Line(4) = {5, 6};
> Line(5) = {6, 7};
> Line(6) = {7, 1};
>
> // layer 2
> Line(11) = {11, 12};
> Line(12) = {12, 13};
> Circle(13) = { 15, 14, 13};
> Line(14) = {15, 16};
> Line(15) = {16, 17};
> Line(16) = {17, 11};
>
> // layer 1
> Line Loop(7) = {1,2,-3,4,5,6};
> Plane Surface(8) = {7};
> Recombine Surface {8};
>
> // layer 2
> Line Loop(17) = {11,12,-13,14,15,16};
> Plane Surface(18) = {17};
> Recombine Surface {18};
>
> // join layer 1 and layer 2
> Line(21) = {1, 11};
> Line(22) = {2, 12};
> Line(23) = {3, 13};
> // no need for point 4 as is central point for circle.
> Line(25) = {5, 15};
> Line(26) = {6, 16};
> Line(27) = {7, 17};
>
> Transfinite Line {21, 22, 23, 25, 26, 27} = 1 Using Progression 1;
>
> Line Loop(28) = {11, -22, -1, 21};
> Plane Surface(29) = {28};
> Line Loop(30) = {12, -23, -2, 22};
> Plane Surface(31) = {30};
> Line Loop(32) = {13, -23, -3, 25};
> Ruled Surface(33) = {32};
> Line Loop(34) = {15, -27, -5, 26};
> Plane Surface(35) = {34};
> Line Loop(36) = {16, -21, -6, 27};
> Plane Surface(37) = {36};
> Line Loop(38) = {14, -26, -4, 25};
> Plane Surface(39) = {38};
>
> Transfinite Surface {35} = {17, 16, 6, 7};
> Transfinite Surface {37} = {11, 17, 7, 1};
> Transfinite Surface {29} = {11, 12, 2, 1};
> Transfinite Surface {31} = {13, 12, 2, 3};
> Transfinite Surface {33} = {15, 13, 3, 5};
> Transfinite Surface {39} = {16, 15, 5, 6};
> Recombine Surface {35, 37, 29, 31, 33, 39};
> Surface Loop(40) = {35, 18, 29, 31, 33, 8, 39, 37};
> Volume(41) = {40};
>
> _______________________________________________
> gmsh mailing list
> gmsh at geuz.org
> http://www.geuz.org/mailman/listinfo/gmsh
>   


-- 
Dr. Ir. Ruth V. Sabariego
University of Liege, Institut Montefiore,
Dept. of Electrical Engineering & Computer Science, 
Applied & Computational Electromagnetics (ACE),
Sart Tilman Campus, Grande Traverse, 10 (B28), B-4000 LIEGE, Belgium
phone: +32-4-3663737 -- fax: +32-4-3662910 -- http://elap.montefiore.ulg.ac.be/