Thank you for your reply, I will try it.
Sorry for the latest line in my previous post "Salome is written in python which is no faster than C++ so ... " because it might sounded judgemental which was not my intention. kind regards Andrew tsiantis 2016-08-28 17:32 GMT+03:00 Christophe Geuzaine <[email protected]>: > > > On 28 Aug 2016, at 13:57, andrew <[email protected]> wrote: > > > > Hi, > > > > Thank you for your response. > > > > I have tried the suggestion you made but this way I don't get the > internal surfaces which I need. The surface mesh is constructed correctly > but as you can see from the first image I don't have the internal regions. > I do get the points but openfoam does not understand them no matter what I > do. In the second image is the mesh that I want with the internal surfaces. > > > > In the third image is a mesh I get with the loops but without the 'Line > In Surface' set of commands where you can see that I get a bad mesh near > the narrow areas where the mesh crosses the boundaries of the loop lines. I > would expect that since I construct the surface with the loops, even if > they were of zero width, they would be embedded in the surface since its > creation making the need for the 'Line In Surface' commands obsolete. > > > > I see; indeed this is a valid approach. > > I have recoded the "Coherence Mesh;" function to make it much faster. > Could you download the next build and give it a try? > > Thanks for the detailed feedback, > > Christophe > > > > > Anyway I found a workaround but it involves the Salome mesh generator. > > > > In the first step I create the mesh in Gmsh without the coherence > function. I save it in unv format. I reload it in Salome and I remove the > duplicate nodes there with 'merge nodes'. I delete the 'vol' since I don't > need it and I save the mesh with only the surfaces I need again in unv > format. > > > > It sounds cybersome but all these are done by scripts and Salome needs a > few minutes to load a 3+ million cells mesh and save it back and less than > a minute to remove the duplicates. Gmsh needs a few minutes for the mesh > and 2+hrs for the removal so the procedure through Salome is way faster. > > > > Salome is written in python which is no faster than C++ so I guess the > coherence routine in gmsh could take a refinement to a faster way. > > > > Kind regards > > > > Andrew Tsiantis > > > > > > 2016-08-28 12:10 GMT+03:00 Christophe Geuzaine <[email protected]>: > > > > Andrew, > > > > The problem actually seems to come from the way you define the surface: > can you regenerate your geometry script after > > > > - removing all the zero-area line loops (e.g. "Line Loop(6) = {5, -5};") > > - removing these loops from the definition of the main surface (i.e. > simply have "Plane Surface(1) = {205};") > > > > With this you should not have duplicate vertices anymore, which should > make "Coherence Mesh" unnecessary. > > > > Let us know, > > > > Christophe > > > > > > > On 21 Aug 2016, at 17:33, andrew <[email protected]> wrote: > > > > > > hi, > > > > > > Thank you for the response. The file I submitted was a small one and > the problem was not so obvious. I am attaching a 'real' file that I use on > my simulations. It has 3000 cuts in it. This takes 2 hours on a quad core > and 1+ hour on a i7 @4ghz. I am using the version 2.13.1. > > > > > > Kind regards > > > > > > Andrew Tsiantis > > > > > > > > > 2016-08-21 17:50 GMT+03:00 Christophe Geuzaine <[email protected]>: > > > > > > > On 19 Aug 2016, at 21:34, andrew <[email protected]> wrote: > > > > > > > > Hi, > > > > > > > > I try to create a 3d mesh from an extruded 2d mesh. The mesh is a > simple box but with cuts in it of zero width. The geometry is created ok > and the meshing even when I have 2000-3000 cuts is done in less than a few > minutes. However when I convert the mesh for use with openfoam I was > getting errors. By adding the command 'Coherence mesh;' after the creation > of the mesh, the mesh is converted correctly for use with openfoam by using > the ultility 'gmshToFoam'. > > > > > > Indeed, it's a limitation of our extrusion algorithm with embedded > curves ("Line In Surface"): it currently creates duplicate vertices. The > real fix is thus for us to enhance extrusion of embedded curves, but it's > not trivial due to the way extruded meshes are generated. > > > > > > > The problem is in the use of the 'Coherence Mesh'. It takes almost > two hours to execute while the meshing takes a few minutes. Is there a way > to improve the Coherence command or to make the same geometry without the > duplicate nodes that need so much time to be removed? > > > > > > > > I attached a file that needs 2.5 minutes on a quad core for meshing > and more than ten minutes to remove 1600 duplicates. > > > > I have to create thousands of these meshes so a speedup would be > welcomed. > > > > > > > > > > That seems a bit slow: on my laptop meshing and duplicate removal take > about the same time (2 minutes each). Which version of Gmsh do you use? > > > > > > > kind regards > > > > > > > > Andrew tsiantis > > > > > > > > <se.geo>_______________________________________________ > > > > 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 > > > > > > Tetrahedron V, July 4-5 2016: http://tetrahedron.montefiore.ulg.ac.be > > > Free software: http://gmsh.info | http://getdp.info | > http://onelab.info > > > > > > > > > <3k_cuts.zip>_______________________________________________ > > > 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 > > > > Free software: http://gmsh.info | http://getdp.info | http://onelab.info > > > > > > <gmsh-1.jpg><gmsh-2.jpg><gmsh-3.jpg><se.geo>________________ > _______________________________ > > 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 > > Free software: http://gmsh.info | http://getdp.info | http://onelab.info > >
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