[Gmsh] export only quadrangle elements in a mesh

[Christophe Geuzaine]

Umut Tabak wrote:
> Dear all,
> 
> I am a rather new user of gmsh who spent the all sunday afternoon for a 
> problem in gmsh. I would like to export/write only quadrangle mesh 
> information, binary or ascii does not matter. However when I use the 
> t6.geo tutorial file with some modifications I am getting as the output 
> all the relevant element information. I only need the element 
> connectivities for real elements(in a finite element context, I only 
> need the quadrangles/triangles) where I can continue to numerical 
> gaussian integration to generate element matrices in my own code. Is 
> there a way to somehow export only this information or is that possible 
> to make a seperate section in the output file furnished with this 
> information only? For instance only elements  9 to 12 so that I will 
> have the necessary connectivity...
> 

Define a single Physical Surface.


> Thanks in advance for the replies...
> 
> Output of a my simple grid information
> 
> $MeshFormat
> 2 0 8
> $EndMeshFormat
> $PhysicalNames
> 1
> 100 "My fancy surface label"
> $EndPhysicalNames
> $Nodes
> 9
> 1 0 0 0
> 2 0.1 0 0
> 3 0.1 0.3 0
> 4 0 0.3 0
> 5 0.04999999999991952 0 0
> 6 0.1 0.150000000000104 0
> 7 0.05000000000012142 0.3 0
> 8 0 0.150000000000104 0
> 9 0.05000000000000205 0.1500000000000936 0
> $EndNodes
> $Elements
> 12
> 1 15 3 1 1 0 1
> 2 15 3 1 2 0 2
> 3 1 3 99 1 0 1 5
> 4 1 3 99 1 0 5 2
> 5 1 3 99 2 0 3 6
> 6 1 3 99 2 0 6 2
> 7 1 3 99 4 0 4 8
> 8 1 3 99 4 0 8 1
> 9 3 3 100 6 0 1 5 9 8
> 10 3 3 100 6 0 8 9 7 4
> 11 3 3 100 6 0 5 2 6 9
> 12 3 3 100 6 0 9 6 3 7
> $EndElements
> 
> --
> U.T.
> --
> There are some things which cannot
> be learned quickly, and time, which is all we have,
> must be paid heavily for their acquiring.
> They are the very simplest things,
> and because it takes a man's life to know them
> the little new that each man gets from life
> is very costly and the only heritage he has to leave.
> - Ernest Hemingway 
> 
> 
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> 


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