[Gmsh] Preventing gmsh from adding additional nodes to surface edges composed of line segments

Christophe Geuzaine cgeuzaine at ulg.ac.be
Thu Apr 16 13:42:03 CEST 2009


Knell, Sascha wrote:
> Hi,
> 
>  
> 
> I intend to use gmsh in batch mode to mesh polygonal plane surfaces 
> whereas nodes of the final mesh may only lie on predefined, equally 
> spaced spots on the straight edges of the surface. The distance of these 
> spots may not differ by more than factor two on the different edges of 
> the surface. I tried to realize this by constructing an edges from 
> several aligned lines and setting the minimum / maximum characteristic 
> length to the minimum / maximum desired node distance. Regrettably, some 
> of the longer lines exhibited additional nodes after meshing. I guess 
> that I have misinterpreted the meaning of the characteristic length.
> 
>  
> 
> Triangle, by Jonathan Richard Shewchuk, has an option to prevent the 
> generation of additional nodes on line segments. Is there a way 
> achieving the same in gmsh? I would prefer to use gmesh, since eyeball 
> comparison indicates that gmsh produces meshes of better quality.
> 
>  

Hi Sascha - To enforce that the segments only have 2 vertices whatever
the prescribed characteristic length, you could do

Transfinite Line "*" = 2;


> 
> Thanks in advance.
> 
>  
> 
> Best regards,
> 
>  
> 
> Sascha Knell
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine