[Gmsh] How to output the master and slave node connection information when the periodic surfaces are generated by using the option of extrude + layers?

Junhui Liu jhliu at lcp.nrl.navy.mil
Fri Feb 24 01:27:12 CET 2017

I use Extrude command with layers to generate boundary-layer unstructured mesh. The recombine command is not used, so the mesh remains as unstructured.  It appears that if the periodic surfaces are generated by using extrude command with layers specified, the msh (tetral mesh) data will not have the information of the slave and master nodes. I need to export the mesh data to a existing CFD software, and need to know the node connection between the Master and Slave periodic surfaces. The existing CFD software does not care if the mesh appears to be structured or unstructured. It only cares if the mesh is tetrahedron mesh. The following attached lines generate a box with structured tetrahedron mesh. The mesh data does give the Slave and Master surface entity numbers, but it does not give the nodes associated with them. Is there a way I can output the slave and master node information when periodic surfaces are generated by using extrude command with layers specified?

Thanks a lot for your help.


>>>>>>>>>>>> box.geo >>>>>>>>>>>>>>>>

lc = 0.1;
Point(1) = {0.0, 0.0, 0.0, lc};
line_extrude[] = Extrude {1.0, 0.0, 0.0} {Point{1}; Layers{10};};

surface_extrude[] = Extrude {0.0, 1.0, 0.0} {Line{line_extrude[1]}; Layers{10};};

Volume_extrude[] = Extrude {0.0, 0.0, 1.0} {Surface{surface_extrude[1]}; Layers{10};};

surfMaster = surface_extrude[1];
surfSlave = Volume_extrude[0];

boundMaster[] = Boundary{Surface{surfMaster};};
boundSlave[] = Boundary{Surface{surfSlave};};
Periodic Surface surfSlave { boundSlave[] } = surfMaster { boundMaster[] };

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