Hello

thanks for the clarifications - i will generate the grid in my code instead of 
trying to load it from a file...

-- Mihai



________________________________
Von: Wolfgang Bangerth <[email protected]>
An: [email protected]
CC: Michael Rapson <[email protected]>; mihai alexe <[email protected]>
Gesendet: Samstag, den 5. Juni 2010, 19:11:16 Uhr
Betreff: Re: [deal.II] problem with writing/reading mesh in ucd format


> It still might be related to the hanging nodes, because the same
> method is used to read the mesh in whether your use dg or normal. I
> believe that the method used to read the mesh does not support hanging
> nodes. I.e. if you have a cell refined further than its neighbors it
> will have a node on the face of its neighbors and I don't think this
> is supported when the mesh is read.

Indeed, and the GridIn class in fact says so:
.............................
Since the coarse mesh fed into a @p Triangulation object cannot have
hanging nodes, strange things will happen if the input file has them. This
is due to the fact that most mesh description formats do not store
neighborship information between cells, so the grid reading functions have
to regenerate it. They do so by checking whether two cells have a common
face. If there are hanging nodes in a triangulation, adjacent cells have no
common (complete) face, so the grid reader concludes that the adjacent
cells have no neighbors along these faces and must therefore be at the
boundary. In effect, an internal crack of the domain is introduced this
way. Since such cases are very hard to detect, the library does not make
any attempt to abort on such situations, and you will get a triangulation
that probably does not do what you want.
.............................

This is a frequently asked question, so if anyone has suggestions on how to 
irmprove this text I'd be happy to change it!

Best
W.

-------------------------------------------------------------------------
Wolfgang Bangerth                email:            [email protected]
                                 www: http://www.math.tamu.edu/~bangerth/

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