[Gmsh] Forcing all jacobians to be positive

[Christophe Geuzaine]

> On 31 May 2020, at 17:12, Carole-Anne Daunais <carole-anne.daunais at polymtl.ca> wrote:
> 
> Thank you Christophe for this quick answer!
> What do you mean by setting the size directly? Is there another way I can set all shapes to be hexs instead of tets? I looked it up in the Archives but couldn't find.
> 

I didn't understand that you want all-hexes. Can you try the latest dev snapshot with Mesh.HighOrderOptimize = 1 or 2, and Mesh.ElementOrder = 1 ? The optimization will be applied before the subdivision, which should improve things.


> Thank you
> 
> Christophe Geuzaine <cgeuzaine at uliege.be> a écrit :
> 
>>> On 29 May 2020, at 20:48, Carole-Anne Daunais <carole-anne.daunais at polymtl.ca> wrote:
>>> 
>>> Hi,
>>> I am using GMSH 4.5.6 to generate a 3d mesh. I used the following 2 lines in the .geo file to ensure that no element would have a jac.<0.
>>> 
>>> Mesh.ElementOrder = 2;
>>> Mesh.HighOrderOptimize = 1;
>>> 
>>> It unfortunately didn't work for me. The mesh is generated, but the software failed (froze). Is there another way I can force all jacobians to be positive when creating my mesh?
>>> 
>> 
>> It works fine here. However you should remove "Mesh.SubdivisionAlgorithm = 2;" (and set the sizes you want directly), as this makes it harder for the optimizer.
>> 
>> You can also use "Mesh.HighOrderOptimize = 2;", which will apply a global elastic smoothing step before the brute-force optimization.
>> 
>> Christophe
>> 
>> 
>> 
>> 
>>> Thank you,
>>> 
>>> Carole-Anne
>>> 
>>> 
>>> 
>>> 
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>> 
>> —
>> Prof. Christophe Geuzaine
>> University of Liege, Electrical Engineering and Computer Science
>> http://www.montefiore.ulg.ac.be/~geuzaine
> 
> 
> 
> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine