Dear Randal, If you can import the geometry as e.g. a STEP file in Gmsh, you can indeed split it with cutting planes. See t20 : http://gmsh.info/dev/doc/texinfo/gmsh.html#t20
If you cut the tetrahedral mesh in a brute-force way you will end up with polyhedra, and generally very poorly shaped elements. Christophe > On 24 Apr 2020, at 06:49, Andress <randalandress1...@comcast.net> wrote: > > Background > > I am doing Finite Element Analysis to study the flow of electric current in > persons and animals due to stray electric current in bodies of water. I am > using FEAtool(a MATLAB plugin) which employs gmsh to generate grids from > geometries. > > Part of my analysis involves the calculation of the total current through > (perpendicular to) the cross section of a sub-domain which is bordered by the > intersection of a cut plane and the subdomain surface. This current is the > integral of current density over the area of the cross section. > > FEAtool does this integration but only over a surface that is a boundary of > the subdomain. > > Here is an example (See attached illustrations.): > > Geometry: a 1m cube (subdomain 2) containing a component (subdomain 1) made > of 4 joined cylindrical sections. > > Boundaries: 5V/0V on the opposite faces of the cube that are perpendicular to > the axes of the cylinders and zero current on the other cube faces. > > Solution: current density is plotted and a YZ plane is cut through it in the > center (at x = 0.5). > > I want to calculate the current flowing through each of the small connecting > cylinders by integrating the current density over the two circular, planar > intersections of the cut plane and the two small cylinders. > > In order to do this wholly within FEAtool, I must create (geometry) the small > cylinders so that they are in two pieces and simply share a face/boundary. > That way there is a pre-defined boundary over which FEAtool can do the > integration. > > Sometimes this is not possible/convenient because the model geometry has been > imported and/or is quite complex (such as that of a human body) or because > the decision to make such a measurement/cut-plane is made only after the > model and mesh is completed and the solution is being examined. > > Question > > If I export the model geometry and/or the mesh from FEAtool to gmsh can the > model/mesh be split by a designated plane within gmsh so that, when exported > and imported back into FEAtool, the sub-domains intersected by the plane > would have true faces/boundaries so they could be designated in an > integration? > > If possible, but not required, I would like to be able to designate the > sub-domains to be split by the cut plane in gmsh so as to not split a > sub-domain over which integration is not needed. > > From the FEAtool perspective, see: > http://forum.featool.com/Integration-of-Current-Density-over-Slice-Intersection-td180.html > > Kind regards, > Randal > > > > > > > > > > <cylinders-in-box-geometry.jpg><cylinders-cut-plane-to-integrate.jpg><cylinders-cut-plane-to-integrate-yzpl...@50cm.jpg>_______________________________________________ > gmsh mailing list > gmsh@onelab.info > http://onelab.info/mailman/listinfo/gmsh — Prof. Christophe Geuzaine University of Liege, Electrical Engineering and Computer Science http://www.montefiore.ulg.ac.be/~geuzaine _______________________________________________ gmsh mailing list gmsh@onelab.info http://onelab.info/mailman/listinfo/gmsh
