[Gmsh] Mesh partition - point and line elements

[sguzik at arrow.utias.utoronto.ca]

Quoting Umut Tabak <u.tabak at tudelft.nl>:

> B. Lazarov wrote:
>> Hello,
>>
>> I am trying to partion simple mesh using the partitioning libraries comming
>> with GMSH. The partitioning is fine however if I define physical lines and
>> physical points in the geo file,  in the resulting mesh file the line or the
>> point element  belong to partition 0.  For surface elements the partitioning
>> is done properly. Is it a bug? Or there is some other way around this
>> behaviour.
>>
>> Best regards,
>> Boyan
>>
>>
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> Developers will reply it better but as far as I read from the METIS
> manual (which is the default graph partitioner in Gmsh), it can handle
> quadrangles, triangles, hexahedra and tetrahedra so it works for these
> elements. There are no algorithms for points and lines as I understand,
> I have not read about Chaco partitioner though.
>
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>
Currently, Gmsh can only partition the highest-dimension elements in a  
mesh.  The partition information is then propagated to lower-dimension  
elements but only those on the extents of the mesh.  For  
lower-dimension elements in the interior, it is (possibly) ambiguous  
to which partition they belong so they are not labeled.

It is entirely possible to add the lower-dimension elements to the  
partitioning graph -- however, I imagine this would also require  
weighting the elements, depending on what is needed.  This  
functionality is not currently implemented through the Gmsh interface  
but can be achieved by using Metis or Chaco directly.

Boyan, you aren't the first to ask about partitioning lines and  
points.  If there is some consensus on the partitioning requirements,  
it probably can be implemented in Gmsh.  How would you need the lines  
and points partitioned relative to the surface elements?

Stephen


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