[Gmsh] lower limit for characteristic length

[Christophe Geuzaine]

Zenker, Dr. Matthias wrote:
> Hi there,
>  
> the question remains: is there a lower limit for the characteristic 
> length cl, and why does gmsh crash when some points have a small cl?

It shouldn't crash, except when "cl" divided by the overall size of 
model is getting close to machine accuracy (or more accurately, close to 
the value of the random pertutbation used in the meshing algorithms, 
which is 1e-9 by default).

Could you send a file that shows the problem?


> I would like to add another one: Is it possible that gmsh ignores the cl 
> of the control points of a spline except for the first and last one? If 

That's what Gmsh does: the cls of the control points are ignored.



> so, is there a way to force gmsh to take into account the cl of the 
> intermediate points also?
>  
> Best regards,
>  
> Matthias
> 
>     ------------------------------------------------------------------------
>     *From:* gmsh-bounces at geuz.org [mailto:gmsh-bounces at geuz.org] *On
>     Behalf Of *Zenker, Dr. Matthias
>     *Sent:* Monday, November 17, 2008 10:49 AM
>     *To:* gmsh at geuz.org
>     *Subject:* Re: [Gmsh] lower limit for characteristic length
> 
>     I was wrong, it crashes also for cl=0.0005 (but after a looong time,
>     and with a runtime error).
> 
>         ------------------------------------------------------------------------
>         *From:* gmsh-bounces at geuz.org [mailto:gmsh-bounces at geuz.org] *On
>         Behalf Of *Zenker, Dr. Matthias
>         *Sent:* Monday, November 17, 2008 10:16 AM
>         *To:* gmsh at geuz.org
>         *Subject:* [Gmsh] lower limit for characteristic length
> 
>         Hi,
> 
>         I wonder if there is a lower limit for the characteristic
>         length. I have a rather simple 2D geometry, and if I set the cl
>         for just two points to 0.0001, gmsh crashes during the meshing
>         after having given the error message "3 identical points in
>         Qtest". The .gmsh-errors file is not written. With cl=0.0005,
>         this does not happen (but it takes veeery long to compute the mesh).
> 
>         Best regards,
> 
>         Matthias
> 
>         ----------------------------------------------------------------
>         ERBE Elektromedizin GmbH
>         Dr.rer.nat. Matthias Zenker
>         Dipl. Phys.
>         Grundlagenentwicklung Technologie
>         Waldhoernlestrasse 17
>         D-72072 Tuebingen
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> 
>           	  	 
> 
>         ERBE Elektromedizin GmbH
>         Firmensitz: 72072 Tuebingen
>         Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
>         Registergericht: Stuttgart HRB 380137
> 
> 
> 
> 
>       	  	 
> 
>     ERBE Elektromedizin GmbH
>     Firmensitz: 72072 Tuebingen
>     Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
>     Registergericht: Stuttgart HRB 380137
> 
> 
> 
> 
>   	  	 
> 
> ERBE Elektromedizin GmbH
> Firmensitz: 72072 Tuebingen
> Geschaeftsfuehrer: Christian O. Erbe, Reiner Thede
> Registergericht: Stuttgart HRB 380137
> 
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine