Hi Mark, in the meantime, I have discovered two (at least partial) solutions on the Elmer side:
1) At mesh import, Elmer can merge nodes which are near to each other. I order to use this, both surfaces have to be meshed with the same characteristic length. The threshold distance for node merging is a parameter you can set. Drawback: If there are several interfaces with different mesh widths, this method might fail. 2) By "misusung" periodic boundary conditions, Elmer can be told that certain variables are continuous at the interface even if the meshes do not match. I did not use this yet, and it seems that care has to be taken in some cases, e.g. with direct solvers. Other FEM programs might have similar possibilities. But still, a proper cleanup of double interfaces on gmsh side would be the best solution since it tackles the cause of the problem directly. So if there is such a solution someday, I would still be most interested (and I might not be the only one). Best regards, Matthias ---------------------------------------------------------------- ERBE Elektromedizin GmbH Dr.rer.nat. Matthias Zenker Dipl. Phys. Grundlagenentwicklung / Fundamental Development Waldhoernlestrasse 17 D-72072 Tuebingen Phone + 49 (0) 7071 - 755 226 Fax + 49 (0) 7071 - 755 5226 E-Mail: <mailto:[email protected]> URL: http://www.ERBE-med.de ---------------------------------------------------------------- -----Ursprüngliche Nachricht----- Von: Mark van Doesburg [mailto:[email protected]] Gesendet: Montag, 13. September 2010 09:58 An: Zenker, Dr. Matthias; [email protected] Betreff: Re: [Gmsh] Double surfaces after STEP import Hello Matthias, I worked on that code and consider it a complete faillure. In many cases the OpenCASCADE algorithms would not find the intersections. The initial version was quite simple but at some point I started to stack one workaround on top of the other. Currently I do not have the time to work on another method, but some algorithms available in CGAL look promising. But in that case I would probably use BRL-CAD to generate the geometry, and importing STEP into BRL-CAD might be sub-optimal. regards, Mark "Zenker, Dr. Matthias" <[email protected]> wrote: Hi, I have not done FEM calculations for some time (a year or so). The last time I did them (using gmsh and Elmer), I had the problem that in geometries imported as STEP files (generated by Solidworks), adjacent bodies have their own external surface, resulting in double surfaces at the interfaces. When I use the mesh generated by gmsh in a FEM calculation (I use Elmer), I get no thermal and electrical connection because the body meshes are not connected at the interface. There have been attempts to clean up double surfaces in gmsh, but I don't know if they have come to a success. Could someone of the developpers update me on this point? Thank you! Matthias ---------------------------------------------------------------- ERBE Elektromedizin GmbH Dr.rer.nat. Matthias Zenker Dipl. Phys. Grundlagenentwicklung / Fundamental Development Waldhoernlestrasse 17 D-72072 Tuebingen Phone + 49 (0) 7071 - 755 226 Fax + 49 (0) 7071 - 755 5226 E-Mail: <mailto:[email protected]> URL: http://www.ERBE-med.de ---------------------------------------------------------------- _____________________________________________________________________ ERBE Elektromedizin GmbH Firmensitz: 72072 Tuebingen Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede Registergericht: Stuttgart HRB 380137 _____________________________________________________________________ ERBE Elektromedizin GmbH Firmensitz: 72072 Tuebingen Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede Registergericht: Stuttgart HRB 380137 _______________________________________________ gmsh mailing list [email protected] http://www.geuz.org/mailman/listinfo/gmsh
