My guess is that you have selected "Save all elements" (or have "Mesh.SaveAll = 1" in your option file). In the MSH2 format, this option discards the physical group definitions. (The MSH4 format's behaviour is more intuitive - it keeps the physical groups.)
Christophe > On 27 Dec 2018, at 20:21, Robbie Jaeger <[email protected]> wrote: > > Hi, > > I'm having difficulty exporting a .msh ASCII file (format version 2) that > includes the physical entity tags for elements. I've created a box volume and > have assigned the 6 surfaces and volume to separate physical groups. I'd like > to export the mesh as a .msh ASCII file (format version 2) as an input for a > finite element program. As such, I am using the physical groups to identify > regions where boundary conditions apply and where material types are > assigned. I'm using gmsh version 4.0.7 Win64 on Windows 10. > > The .geo commands for the box are as follows: > > SetFactory("OpenCASCADE"); > Box(1) = {0, 0, 0, 10, 10, 5}; > Physical Surface("DS") = {2}; > Physical Surface("US") = {1}; > Physical Volume("Solid") = {1}; > Physical Surface("Other Surface") = {3, 5, 6, 4}; > > I created 1d, 2d, and 3d meshes using the GUI. When I export this to a .msh > file (format version 2), the elements are exported with their elementary tags > rather than their physical tags. For example, here is the line from the .msh > file for element 500 which falls on elementary surface 6 and physical surface > 4: > 500 2 2 0 6 15 247 237 > > Three-dimensional elements are similarly exported using their elementary > surface tags. Here is a 4-node tetrahedron within elementary volume 1 and > physical volume 5: > 924 4 2 0 1 169 306 196 293 > > Based on the documentation, I expected the first tag after the number of tags > to be the physical entity tag: > > number-of-tags > gives the number of integer tags that follow for the n-th element. By > default, the first tag is the tag of the physical entity to which the element > belongs; the second is the tag of the elementary geometrical entity to which > the element belongs;... > > However, I'm receiving a zero tag for all elements. Am I misunderstanding the > documentation or is this the intended behavior? Is there a way to export a > .msh with the physical entity tags or do I need to go about this in a > different way? > > Best regards, > Robert Jaeger > _______________________________________________ > gmsh mailing list > [email protected] > http://onelab.info/mailman/listinfo/gmsh — Prof. Christophe Geuzaine University of Liege, Electrical Engineering and Computer Science http://www.montefiore.ulg.ac.be/~geuzaine Free software: http://gmsh.info | http://getdp.info | http://onelab.info _______________________________________________ gmsh mailing list [email protected] http://onelab.info/mailman/listinfo/gmsh
