[Gmsh] Question about parametric nodes and mixed elements

[Christophe Geuzaine]

On 27 Sep 2013, at 17:58, Christophe Geuzaine <cgeuzaine at ulg.ac.be> wrote:

> 
> On 17 Sep 2013, at 16:12, Michael Scheerer <scheerer at fdy.tu-darmstadt.de> wrote:
> 
>> Dear Prof. Christophe Geuzaine,
>> 
>> I'm Michael Scheerer and we meet us during the last Gmesh workshop. I've a short question about parametric nodes (instead of normal nodes).
>> Is there any documentation about? It would be very help full. I've seen, that in available Gmesh importer source code of scientists is only a "not in the spec, not supported" exception, if a msh file contains parametric nodes stuff.
>> 
> 
> Hi Michael,
> 
> There's no documentation yet. Currently the parametric information is stored like this:
> 
> node_num x y z entity_id < dimension parameter ... >
> 
> If entity_id == 0, no dimension and no parameters are given (there's no parametric info)
> 
> If entity_id != 0, the next integer is the dimension of the entity (== the number of parameters that follow), followed by the parameters.
> 

PS: this describes the scheme in the forthcoming MSH3 format. In MSH2, 'entity_id' and 'dimension' are swapped, and parametric coordinates are not saved if dimension==3.

> 
>> Another question is about mixed elements. Performance-wise it would be helpful, if we could use non curved elements in cases, that there are nearly no differences between straight looking  curved elements and possible non curved “replacement” elements. Can you verify the statement, that such a replacement is impossible, because of the fact, that if once one element is curved, all other must be curved too, because of a domino effect?
> 
> It is indeed, unless we allow non-conformal meshes.
> 
> Cheers,
> 
> Christophe
> 
>> 
>> Best regards,
>> Michael Scheerer
>> 
>> ----------------------------------------------------
>> Dipl.-Ing. Michael Scheerer
>> TU Darmstadt, Department of Mechanical Engineering Chair of Fluid Dynamics Petersenstr. 30, 64287 Darmstadt, Germany
>> Phone: ++ 49 (0)6151-16-70960
>> E-Mail: scheerer at fdy.tu-darmstadt.de
>> Home-Page: http://www.fdy.tu-darmstadt.de/
>> 
>> 
> 
> -- 
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science 
> http://www.montefiore.ulg.ac.be/~geuzaine
> 
> 
> 

-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine