Oh, how silly of me to not notice that! Thanks! Gavin Ridley
> On Apr 4, 2019, at 9:00 AM, Christophe Geuzaine <[email protected]> wrote: > > >> On 4 Apr 2019, at 03:32, Gavin Ridley <[email protected]> wrote: >> >> Unfortunately I cannot share this STEP file in particular. It's a bit big >> for sake of example anyways. Even better, could you show how to modify >> import.geo from the demos directory so that the cylindrical surface on the >> inside of the nut is split into two cylinders by a plane perpendicular to >> the axis of the nut's hole? Then one BC could be applied below a certain >> axial level (along the axis of the nut's hole) and a separate one above that >> plane? >> >> Physically, I need to do this since I'm trying to model a pipe which has one >> section of it wrapped in heating tape, and another section insulated. >> >> If this isn't straightforward, I will just go back and modify the CAD. Seems >> that most CAD software has a tool for splitting surfaces. >> > > Sure - you can use boolean operations: > > SetFactory("OpenCASCADE"); > Cylinder(1) = {0.5,0.5,-0.5, 0,0,1, 0.1}; > Rectangle(100) = {0,0,0,1,1,0}; > BooleanFragments{ Volume{1}; Delete; }{ Surface{100}; Delete; } > > Christophe > > >> On Wed, Apr 3, 2019 at 4:13 PM <[email protected]> wrote: >> >> >>> Le 3 avr. 2019 à 21:51, Gavin Ridley <[email protected]> a écrit >>> : >>> >>> Hi Dr. Geuzaine, >>> >>> Thanks for your response. I see the problem here now. It doesn't work after >>> meshing, although the geometry seems to load to the GUI. Unfortunately, I >>> need to split a surface into two surfaces, and it seems there's no way to >>> do that to the STEP file using what's available under the OpenCASCADE >>> kernel right now. >> >> Can you share the STEP file? It should be possible to do what you want >> directly in Gmsh. >> >> >>> I was hoping to be able to convert the STEP to gmsh-style geometry, then >>> delete a surface (and its dependent volumes) and replace it with a new, >>> split one. I'll just have to change the CAD then re-export, I suppose. >>> >>> Thanks again! >>> >>> On Wed, Apr 3, 2019 at 3:11 PM Christophe Geuzaine <[email protected]> >>> wrote: >>> >>> >>>> On 3 Apr 2019, at 18:23, Gavin Ridley <[email protected]> wrote: >>>> >>>> Hi, >>>> >>>> I would just like to note something to the developers regarding a perhaps >>>> unnecessary skipping of surfaces in the code. >>>> >>>> I recently have had to convert a STEP file with fairly complicated >>>> geometry to a GEO. >>> >>> Don't do that. By design, Gmsh never translates from one CAD format to >>> another. The "unrolled GEO" feature is there for unrolling complex GEO >>> scripts. It can indeed export a limited subset of geometrical entities >>> created by other CAD kernels, but it's there only for debugging. >>> >>> If you want to modify a STEP model, set >>> >>> SetFactory("OpenCASCADE"); >>> >>> at the beginning of your script. Since we import STEP models with >>> OpenCASCADE, this will allow you to modify the file directly with >>> OpenCASCADE. See >>> https://gitlab.onelab.info/gmsh/gmsh/blob/master/demos/boolean/import.geo >>> for an example. >>> >>> Christophe >>> >>> >>> >>> >>>> This is done so that I can split one of the surfaces in the STEP file to >>>> set different BCs on different parts of the surface. At the moment, it >>>> appears that gmsh will skip several surfaces in the conversion from STEP >>>> to geo_unrolled unnecessarily: surfaces were left out from the gmsh file. >>>> A warning message comes with this. >>>> >>>> It seems, however, that the skipped surfaces work fine if you just go back >>>> in and add surfaces manually. Gmsh now reads the geo file correctly. >>>> >>>> So, why are these surfaces being skipped? Is there some ambiguity about >>>> their interpretation from STEP? It would be nice to not have to manually >>>> go in and add the surfaces. >>>> >>>> -- >>>> Thanks, >>>> Gavin Ridley >>>> _______________________________________________ >>>> 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 >>> >>> >>> >>> >>> >>> -- >>> Thanks, >>> Gavin Ridley >> >> >> -- >> Thanks, >> Gavin Ridley > > — > Prof. Christophe Geuzaine > University of Liege, Electrical Engineering and Computer Science > http://www.montefiore.ulg.ac.be/~geuzaine > > > _______________________________________________ gmsh mailing list [email protected] http://onelab.info/mailman/listinfo/gmsh
