On 03 Feb 2016, at 18:06, Josefin Ahlkrona <[email protected]> wrote:
Hi,
Thank you for the answer. Is there a way to make structured meshes periodic?
Since it's structured of course the nodes match, but I would like the edges to
match eachother too!
It's possible, albeit tedious: you need to use the "Transfinite" algorithm for
that, and specify the orientions by hand (the automatic mode will not ensure edge
matching). Here's an example:
lc = 0.3;
// example of a purely hexahedral mesh using only transfinite
// mesh constraints
Point(1) = {-2,0,0,lc};
Point(2) = {-1,0,0,lc};
Point(3) = {-1,1,0,lc};
Point(4) = {-2,1,0,lc};
Point(5) = {-2,0,1,lc};
Point(6) = {-1,0,1,lc};
Point(7) = {-1,1,1,lc};
Point(8) = {-2,1,1,lc};
Line(1) = {4,3};
Line(2) = {3,2};
Line(3) = {2,1};
Line(4) = {1,4};
Line(6) = {5,6};
Line(7) = {6,7};
Line(8) = {7,8};
Line(9) = {8,5};
Line(10) = {1,5};
Line(11) = {4,8};
Line(12) = {2,6};
Line(13) = {3,7};
Line Loop(14) = {3,4,1,2};
Plane Surface(15) = {14};
Line Loop(16) = {6,7,8,9};
Plane Surface(17) = {16};
Line Loop(18) = {10,-9,-11,-4};
Plane Surface(19) = {18};
Line Loop(20) = {8,-11,1,13};
Plane Surface(21) = {20};
Line Loop(22) = {12,7,-13,2};
Plane Surface(23) = {22};
Line Loop(24) = {6,-12,3,10};
Plane Surface(25) = {24};
Surface Loop(1) = {17,-25,-23,-21,19,15};
Volume(1) = {1};
Transfinite Line{1:4,6:13} = 5;
// need to specify orientation (through vertex list) by hand to have correctly
// matching volume/surface edges
Transfinite Surface {15} = {1,2,3,4};
Transfinite Surface {17} = {5,6,7,8};
Transfinite Surface {19} = {1,5,8,4};
Transfinite Surface {21} = {4,8,7,3};
Transfinite Surface {23} = {2,6,7,3};
Transfinite Surface {25} = {1,5,6,2};
Transfinite Volume{1} = {1,2,3,4,5,6,7,8};
Best Regards,
Josefin
On 02/03/2016 06:02 PM, Christophe Geuzaine wrote:
On 02 Feb 2016, at 20:59, Josefin Ahlkrona <[email protected]> wrote:
Hi,
I have a cuboid (x,y,z) domain for which i have created tetrahedral, structured
mesh. Now, I want to apply periodic boundary conditions in x, and y direction
and in order to do that I need the mesh to be identical for the x=0 and x=xmax
surfaces, as well as for the y=0 and y=ymax surfaces. It is not sufficient for
only the nodes to match but I also want the edges to match!
I have tried to use the "Periodic Surface" command without success. I have seen several
posts on using the "Periodic Surface" commands without finding a solution for my problem.
The Periodic meshing command only apply to unstructured grids. In your case the grid is
set structured (meshed by extrusion with the "Layers" option).
Could anyone help me?
My geofile looks like this:
cl=1.0;
//cuboid which is 8000,8000,1000 big
Point(1) = {0,0,0,cl};
Extrude {8000,0,0} {
Point{1}; Layers{10};
}
Extrude {0,8000,0} {
Line{1}; Layers{10};
}
Extrude {0,0,1000} {
Surface{5}; Layers{5};
}
boundMaster[] = Boundary{26};
boundSlave[] = Boundary{-8}; //tried plus and minus sign here..
boundMaster2[] = Boundary{22};
boundSlave2[] = Boundary{-14}; //tried plus and minus sign here..
Periodic Surface 18 {boundSlave[]} = 26 {boundMaster[]};
Periodic Surface 14 {boundSlave2[]} = 22 {boundMaster2[]};
Physical Surface(28) = {14}; //y=y0
Physical Surface(29) = {18}; //x=xmax
Physical Surface(30) = {22}; //y=ymax
Physical Surface(31) = {26}; //x=x0
Physical Surface(32) = {5}; //top
Physical Surface(33) = {27}; //bottom
Physical Volume(34) = {1};
Best,
Josefin
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Josefin Ahlkrona
PhD Student
Division of Scientific Computing
Department of Information Technology
Uppsala University
Box 337
SE-751 05 Uppsala
Sweden
Email: [email protected]
Webpage: http://www.it.uu.se/katalog/josah992
Ph: +46-18-4712980
Fax: +46 18 523049, +46 18 511925
