[Gmsh] Elements with negative jacobian after extrusion of a spline

[Jean-François Remacle]

This should be fixed in the highly build

JFR
Le 31 janv. 2013 à 18:39, Christophe Geuzaine <cgeuzaine at ulg.ac.be> a écrit :

> 
> Hi Paul,
> 
> Apparently we broke this (again) in 2.6. (It works fine in 2.5.)
> 
> We will investigate.
> 
> Thanks for the report,
> 
> Christophe
> 
> 
> On 25 Oct 2012, at 17:44, Paul Cristini <cristini at lma.cnrs-mrs.fr> wrote:
> 
>> Hello all,
>> 
>> I am just trying to do the extrusion of a spline and depending on the position of a point of the spline I got 2 elements with a negative jacobian.
>> 
>> Here is the .geo file. If Point(3) = { -L/2,  l+dl/2, 0, lc}; is changed to Point(3) = { -L/2,  l+dl/3, 0, lc}; ,which means that one point is lowered, then no problem.
>> 
>> I am generating all quads meshes and  I am also using second order elements. I noticed that if I use first order or incomplete second order element there is no element with a negative jacobian.
>> 
>> Any idea of what's going on ?
>> 
>> Thanks
>> 
>> Paul
>> 
>> // Gmsh project created on Sat Apr 10 19:26:34 2010
>> lambda = 30;
>> lc=lambda/4;
>> //
>> L  = 10 * lambda; // Width
>> l  =  8 * lambda; // Height
>> dl =  2 * lambda; // Decalage
>> 
>> Point(1) = { L, l+dl, 0, lc};
>> Point(2) = {-L,    l, 0, lc};
>> //
>> Point(3) = { -L/2,  l+dl/2, 0, lc};
>> Point(4) = { 0,  l+dl/3, 0, lc};
>> Point(5) = { L-L/4,  l+dl/2, 0, lc};
>> 
>> //lx1 = newl; Line(lx1) = {cx2, cx1};
>> lx1 = newl; Spline(lx1) = {2, 3, 4, 5, 1};
>> Extrude {0,1.5*lambda,0} {Line{lx1}; Layers{3};Recombine; };
>> 
>> -- 
>> *--------------------------------------------------------------------------*
>> Paul CRISTINI  Charge de Recherche CNRS / CNRS Research Scientist
>> --------
>> CNRS - Laboratoire de Mecanique et d'Acoustique (UPR 7051)
>> 
>> 31 chemin Joseph Aiguier, F-13402 Marseille Cedex 20 - France
>> mailto: cristini at lma.cnrs-mrs.fr
>> phone number: +33 (0)4 91 16 42 89
>> fax number: +33 (0)4 91 16 44 81
>> http://www.lma.cnrs-mrs.fr/
>> *--------------------------------------------------------------------------*
>> 
>> 
>> _______________________________________________
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> 
> -- 
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science 
> http://www.montefiore.ulg.ac.be/~geuzaine
> 
> 
> 

------------------------------------------------------------------
Prof. Jean-Francois Remacle
Universite catholique de Louvain (UCL)
Ecole Polytechnique de Louvain (EPL) - Louvain School of Engineering
Institute of Mechanics, Materials and Civil Engineering (iMMC)
Center for Systems Engineering and Applied Mechanics (CESAME)
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