[Gmsh] Post processing 2nd Order Elements

Christophe Geuzaine cgeuzaine at ulg.ac.be
Thu Jul 10 15:00:58 CEST 2008


Shi Jin wrote:
> Hi there,
> 
> I am trying to visualize data from a FEM simulation using second order Taylor-Hood elements. Although I was able to get some image it is not the second order elements I am trying to see.  Please take a look at the attached image.
> 
>  
> I am using the .msh file format. The mesh was loaded without problem in second order. However, I am not exactly sure what tags I should use for the $NodeData section. I am using the same one for first order elements:
> $NodeData
> 1
> "velocity-2"
> 1
> 0
> 3
> 0
> 1
> 39
> 12   -0.00000
> ...
> I am not sure what the usage of the first a few tags before the one specifying the number of nodes (39 above).
> If you could give some advice, I would greatly appreciate it.

Hi Shi - From the docs:

number-of-string-tags
     gives the number of string tags that follow. By default the first 
string-tag is interpreted as the name of the post-processing view, and 
the second as the name of the interpolation scheme.

number-of-real-tags
     gives the number of real number tags that follow.

number-of-integer-tags
     gives the number of integer tags that follow. By default the first 
integer-tag is interpreted as a time step number, the second as the 
number of field components of the data in the view, the third as the 
number of entities (nodes or elements) in the view, and the fourth as 
the partition index for the view data.


However, the code for drawing high-order post-processing elements using 
the .msh format has not been activated yet. It's almost ready, but not 
quite. It should be available in the next release.

Until then, using the old ".pos" format you will get the same bahaviour 
as ParaView (second order quad split in 4 pieces, etc.).




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