[Gmsh] bug error

[Christophe Geuzaine]

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