[Gmsh] detect negative jacobians

[Bernd Hahnebach]

Thanks Christophe, got again the point! Works quit well for me now.

Is it possible to script the hight order tools in a geo file? I could  
not find anything in this regard (only the window position ?!?)

bernd


Zitat von Christophe Geuzaine <cgeuzaine at ulg.ac.be>:

>
>> On 30 Mar 2016, at 07:30, Bernd Hahnebach <gmsh at b75.ch> wrote:
>>
>> Thanks Christophe!
>>
>> I got the problem of the high order meshes by reading a big part of  
>> the paper. :-) :-)  Is there any user documentation or an example  
>> how to use the HighOrderTools around?
>>
>> Just to get it the right way done. How does it work in the gui?
>>
>
> 1) Load the geometry
> 2) Mesh (e.g. press "3" to do a 3D mesh)
> 3) Open "High order tools"
>    - Choose the polynomial order and press "Generate" (this will  
> create high order elements)
>    - Press "Regularize" (this will optimize the high order elements)
>
>
>> - Load the geometry (in my case a BRep)
>> - make the adjustments on Tools --> Options --> Geometry and Mesh  
>> --> one of them is 2nd order mesh
>> - In GMSH Tree press Mesh 1D, 2D, 3D
>> - on 3D I get negative Jacobians if the mesh order in options is set to two
>> - do not use any optimization, do not use the order buttons (mesh  
>> is 2nd order already)
>> - open HighOrderTools
>> - Generate 2nd order vertices
>> - Regularize with given values
>>
>> - Or do I have to start with a 1st order mesh and use Generate 2nd  
>> order vertices on a 1st order mesh?
>> - Should any of the optimizations be done before the HighOrderTools?
>>
>> kind regards bernd
>>
>>
>> Zitat von Christophe Geuzaine <cgeuzaine at ulg.ac.be>:
>>
>>>
>>>> On 24 Mar 2016, at 19:06, Christophe Geuzaine <cgeuzaine at ulg.ac.be> wrote:
>>>>
>>>>>
>>>>> On 24 Mar 2016, at 12:27, Bernd Hahnebach <gmsh at b75.ch> wrote:
>>>>>
>>>>>
>>>>> What is the recommended way to avoid such negative jacobians?  
>>>>> Attached the geometry of the mesh above.
>>>>>
>>>
>>> And to avoid such negative jacobians, you can use the "High order  
>>> tools" (in the Mesh menu). This is still experimental, but works  
>>> quite well. The algorithms are described (in part) in
>>>
>>> T. Toulorge, C. Geuzaine, J.-F. Remacle, J. Lambrechts. Robust  
>>> untangling of curvilinear meshes. Journal of Computational Physics  
>>> 254, pp. 8-26, 2013.  
>>> http://gmsh.info/doc/preprints/gmsh_untangling_preprint.pdf
>>>
>>> Christophe
>>>
>>>
>>> --
>>> Prof. Christophe Geuzaine
>>> University of Liege, Electrical Engineering and Computer Science
>>> http://www.montefiore.ulg.ac.be/~geuzaine
>>>
>>> Tetrahedron V, July 4-5 2016: http://tetrahedron.montefiore.ulg.ac.be
>>> Free software: http://gmsh.info | http://getdp.info | http://onelab.info
>>>
>>>
>>>
>>
>>
>>
>>
>>
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>
> --
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science
> http://www.montefiore.ulg.ac.be/~geuzaine
>
> Tetrahedron V, July 4-5 2016: http://tetrahedron.montefiore.ulg.ac.be
> Free software: http://gmsh.info | http://getdp.info | http://onelab.info
>
>
>