Hi Arjen - Thanks for your mail: that's definitely a bug. We will investigate.
Arjen Terwisscha van Scheltinga wrote: > Hi, > > I'm currently using gmsh to build a high resolution mesh for the > Canadian Arctic Archipellago (CAA). In order to do this, I have > represented all the islands in the CAA as closed BSplines, and in order > get sufficient resolution I use attractors to define the background > field. For small characteristic lengths the 2D meshing produces weird > results - which I don't get. > > To better understand why, and to make sure its not a issue of > geometrical model for the CAA, I've investigated this issue in a very > simplified geometry. Same problem persists. (I've attached a two pdfs of > the geometry and mesh, as well as the .geo file). The geometry is > basically two islands defined by closed BSPlines in a circle. The > problem is the 'teardrop'-shaped areason the left-bottom side of the > 'islands', which is where the beginning and end of the BSPline are > joined together. > Some further observations: > - it seems to be independent of the meshing algorithm; > - is works OK if I use ordinary splines; > - rearranging the control points of the BSpline, don't help - it just > moves the problem to another area, which still coincides with the > begin/end point of the BSpline. > - in this area close to the begin/end point is generates triangles > always the begin/end point as one of the three points. > > To me it looks like main problem is the results of the > geometrical/control begin/end point of the BSpline is not at the same > position as the 'physical' begin/end point. The 1D mesh looks OK. > > Anyway, don't know if I can classify this as a bug - if I do something > obviously wrong do tell me, but is seems to me to be to robust to be a > simple mistake on my side. Any ideas? I hope there is a quick fix. > > Apart from this issue, I'm quite happy with gmsh. > > With regards, Arjen > > ================================================== > Arjen Terwisscha van Scheltinga > > Email: [email protected] > Office: Tory 3-129 Phone: (780) 492-3564 > > Department of Earth and Atmospheric Sciences > 1-26 Earth Science Building, University of Alberta > Edmonton, Alberta > T6G 2E3, Canada > > > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > gmsh mailing list > [email protected] > http://www.geuz.org/mailman/listinfo/gmsh -- Prof. Christophe Geuzaine University of Liege, Electrical Engineering and Computer Science http://www.montefiore.ulg.ac.be/~geuzaine _______________________________________________ gmsh mailing list [email protected] http://www.geuz.org/mailman/listinfo/gmsh
