<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:verdana,helvetica,sans-serif;font-size:10pt"><div>On these pictures, you see the surface of the object after meshing, and it is clearly not a cylinder ...<br> Otherwise I checked coordinates of points of the lines obtained by extruding a point (with combined rotation <br>and translation), they are not on the cylinder too, so probably a first step would be to specify directly spline with more than<br> 5 points in order to have curves on the cylinder, and probably split the surfaces into small patches of ruled surfaces that would<br> generate a better approximation of the cylinder. Well, I will try Salome, I hope that Gmsh correctly exploits the CAD informations in order to generate the curved mesh.<br>Thanks for your comments.<br></div><div style="font-family: verdana,helvetica,sans-serif; font-size: 10pt;"><br><div style="font-family:
arial,helvetica,sans-serif; font-size: 13px;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">De :</span></b> David Colignon <David.Colignon@ulg.ac.be><br><b><span style="font-weight: bold;">À :</span></b> Durufle marc <marc_durufle@yahoo.fr><br><b><span style="font-weight: bold;">Cc :</span></b> gmsh@geuz.org<br><b><span style="font-weight: bold;">Envoyé le :</span></b> Dim 27 Décembre 2009, 10 h 26 min 58 s<br><b><span style="font-weight: bold;">Objet :</span></b> Re: [Gmsh] Problems for creating ruled surfaces belonging to a cylinder<br></font><br><br>On 26/12/09 20:58, Durufle marc wrote:<br>> Hello,<br>> your help has been very useful for the problem of the cavity, thanks<br>> very much. I have another problem with<br>> the geo file attached. I want that "ruled surfaces" 36, 38, 40, 46, 48<br>> and 50 are part of a cylinder, so I tried to<br>> construct nurbs which are belonging
the cylinder, but the generated<br>> ruled surfaces are not part of the cylinder :(<br><br>Hi Marc,<br><br>the mesh seems fine here. How do you have verified that these ruled surfaces are not part of the cylinder ?<br><br><br>> Do you know a way to generate those surfaces correctly ?<br><br>We have an option to force the mesh on the surface of a sphere, but not on a cylinder...<br><br><a href="http://geuz.org/gmsh/doc/texinfo/gmsh.html#Surfaces" target="_blank">http://geuz.org/gmsh/doc/texinfo/gmsh.html#Surfaces</a><br><br>Ruled Surface ( expression ) = { expression-list } < In Sphere { expression } >;<br> Creates a ruled surface, i.e., a surface that can be interpolated using transfinite interpolation. The expression inside the parentheses is the ruled surface's identification number; the first expression-list on the right hand side should the identification number of a line loop composed of either three or four elementary
lines. The optional In Sphere argument forces the surface to be a spherical patch (the extra parameter gives the identification number of the center of the sphere).<br><br><br>Is it possible<br>> (or soon possible) to specify directly<br>> a nurb surface in gmsh (not only a nurb curve), so that I could<br>> approximate the cylinder with nurb patches ?<br><br><br>I don't think we will add nurbs surfaces support natively in Gmsh ( Christophe, Jean-François, a comment ? )<br><br>You could/should generate these critical nurbs surfaces in a real CAD software/Solid Modeler<br>( Salome <a href="http://www.salome-platform.org/" target="_blank">http://www.salome-platform.org/</a> is free and based on the same CAD engine as Gmsh, OpenCascade),<br> export it in the STEP format, import in Gmsh, finalize the geometry and mesh ...<br><br>Regards,<br><br>Dave<br><br>--<br>David Colignon, Ph.D.<br>Collaborateur Logistique du F.R.S.-FNRS<br>CÉCI -
Consortium des Équipements de Calcul Intensif<br>ACE - Applied & Computational Electromagnetics<br>Institut Montefiore B28<br>Université de Liège<br>4000 Liège - BELGIQUE<br>Tél: +32 (0)4 366 37 32<br>Fax: +32 (0)4 366 29 10<br>WWW: <a href="http://hpc.montefiore.ulg.ac.be/" target="_blank">http://hpc.montefiore.ulg.ac.be/</a><br>Agenda: <a href="http://www.google.com/calendar/embed?src=david.colignon%40gmail.com" target="_blank">http://www.google.com/calendar/embed?src=david.colignon%40gmail.com</a><br><br></div></div>
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