I have looked around on the list a bit yesterday and have noticed that the question of doing intersections or surface patches has come up quite a few times. I realize that Gmsh is not a solid modeler (although I might be interested in hearing of a simple, perhaps open source, command line, solid modeler that one could provide geometry to and get a file importable to Gmsh for meshing... is this essentially Open CASCADE?), and I've also seen that there is the ruled surface functionality that provides a mechanism for interpolating or pinning a patch to a sphere, but there isn't a convenient way of doing this with cylinders.
For me this has become of interest for doing electrostatics simulations where one would like to have patches to define as electrodes rather than points or ad-hoc selection of neighboring faces to fit a geometry after mesh generation, e.g.: http://eidors3d.sourceforge.net/tutorial/netgen/netgen_gen_models.shtml or http://eidors3d.sourceforge.net/tutorial/EIDORS_basics/forward_solvers_3d.shtml What I've come to ask/suggest is perhaps something could be done with fields/attractors/thresholds for defining these patches? Since this functionality already provides a way to control element sizes as a function of distance, including restrictions of whether to apply these parameters to given surfaces or volumes, could there not be a relatively simple way to define a patch from these or the code that is providing this functionality (with or without actually varying mesh density). Maybe there's already a convenient way to select elements resulting from the current functionality just based on size and distance, but it would be nice to have form a clean line/arc rather than just selecting triangles under a given distance (either in the surface or euclidean distance would be fine). It seems like the easiest way to get the desired effects currently is to use splines where one calculates out the line/arc along curved surfaces and the resulting spline can be used, but this has some downsides in that I'm not completely sure if the splines really do always end up in the desired curved face. It seems like if one uses enough or if the geometry is correct it may just fall below the threshold of complaint one might find from embedding a line in a surface if enough points are used? Best. -jsnyder -- James Snyder Biomedical Engineering Northwestern University http://fanplastic.org/key.txt ph: (847) 448-0386 _______________________________________________ gmsh mailing list [email protected] http://www.geuz.org/mailman/listinfo/gmsh
