[Gmsh] Joining two pipes

Martin Vymazal martin.vymazal at vki.ac.be
Wed Aug 4 20:06:55 CEST 2010


Hello,

  I would like to ask if anyone has an idea how (if at all) to join  
two cylindrical surfaces in gmsh. I have an 'msh' file after  
conversion from CAD data. The file contains 2 pipes which have the  
same axis but slightly different diameters, one following after the  
other. There's a small gap between the end of the first pipe and the  
beginning of the second pipe that I'd like to cover with a surface  
mesh, thus joining the two pipes.
  I have a circle (elementary entity number 1), which is the 'outlet  
ring' of the first pipe and another circle (elementary entity # 2) -  
'inlet ring' of the second pipe. Moreover, there's a line number 3  
joining one point of the first circle with another point on the second  
circle. These three lines form sort of a 'conical outline' - I have 2  
bases with slightly different radiuses and one surface line connecting  
them. I thought I could write this in my geo file (after merging the  
mesh with the two pipes):

   l1 = newreg;
   Line Loop(l1) = {1,2,3};
   Ruled Surface(newreg) = {l1};

Unfortunately, gmsh meshes only the surface defined by circle 1,  
instead of meshing the conical surface that I tried to define.

Could you please tell if what I'm trying to do is feasible? If so, do  
you have an idea how to do it?

Best regards,

    Martin Vymazal

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