[Gmsh] make a hexa second order mesh out of a hexa first order mesh

[Christophe Geuzaine]

> On 13 May 2016, at 07:16, Bernd Hahnebach <gmsh at b75.ch> wrote:
> 
> Found the culprit :-) but it does not solve my problem :-(
> 
> If either "Mesh --> set Order 2" or "Mesh -> Hight order tools" is used on a hexahedron8 it does not make a hexahedron20 but a hexahedron27 instead. Means a node is not only made on any edge center point but on any face center point too.
> 

Use "Mesh.SecondOrderIncomplete = 1;" in your script (or "Tools->Options->Mesh->General : Use incomplete elements" in the GUI).


> Neither unv nor inp export of GMSH support hexahedron27. A hexahedron20 can be exported to unv and inp and these files are fine.
> 
> This means back to the first question. Is it possible to make a hexahedron20 element out of an hexahedron8 in gmsh?
> 
> kind regards bernd
> 
> attached a hexa20.unv and hexa8.unv to test with.
> 
> 
> Zitat von Bernd Hahnebach <gmsh at b75.ch>:
> 
>> More informations in this regard ...
>> 
>> - open file b5__hexa8_coarse.msh
>> - in GMSH Tree click on Mesh --> Set order 2
>> - Menue Tools --> Options --> Mesh --> Visibility --> activate Nodes
>> - It seams we have got a second order mesh ?!
>> 
>> - Menue Tools --> Visibility --> Numeric --> click on hide elements  (put in * before) --> click on show elements (put in 50 before)
>> - screen is attached --> it really seams to be a hexa20 mesh
>> 
>> - save as msh --> reload --> still a hexa20 mesh
>> - save as unv --> reload --> no hexa20 mesh, it is a  hexa8 mesh
>> 
>> Could it be hexa20 ist not supported in GMSH unv export ?? Could  someone else give more informations in this regard?
>> 
>> GMSH 2.12.0
>> 
>> kind regards bernd
>> 
>> 
>> 
>> Zitat von Bernd Hahnebach <gmsh at b75.ch>:
>> 
>>> Dear gmsh folks,
>>> 
>>> attache a coarse hexa first order mesh. I'd like to get an second  orde  hexa mesh out of this. I found the hight order tools can be  used to  create the appropriate nodes for a second order hexa mesh.  But how do  I create elements out of the nodes.
>>> 
>>> kind regards bernd
>>> 
>>> 
>> 
>> 
>> 
>> 
> 
> 
> 
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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
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