[Gmsh] bug error
Christophe Geuzaine
cgeuzaine at ulg.ac.be
Tue Oct 7 21:16:41 CEST 2008
ZhouBin wrote:
> Dear Christophe,
>
> Sorry to disturb you again. This is maybe my ability to use Gmsh.
>
> As you could see from the attached file, I have a line tangential to the circle. Since circle is actually a regular polygon with many sides. There will be a gap between this line and the "Gmsh circle".
>
The geometrical object "circle" in Gmsh is really a circle, not a
polygon. (It just looks like a polygon if you zoom in because it's drawn
that way.)
Now, Gmsh does not compute intersections, so if a line is supposed to be
tangent to a circle arc, you have to split the line and the circle arc
in two (i.e., introduce the tangency point explicitly) before you can mesh.
> Question 1: On what basis does the grid generator decide when a line and a polygon meet, and when there is a small gap through which fluid can flow?
>
> Question2: What is done when a circle is so small that the polygonal representation is only one pixel per polygon side? Or worse, less than one pixel?
>
> Thank you very much if you could spend some time for my problem.
>
> Best regards,
>
> Bin
>
>
>
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--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine