[Dune] Boundary conditions

[Oliver Sander]

Hi Arne!
>
> I have some problems understanding how the boundary and the boundary  
> conditions should be specified. I see the BoundaryConditions class in  
> dune-disc, but how can these flags be associated with the vertices in  
> the grid?
>   
Currently there is no well-designed handling of boundary conditions.
The stuff in dune-disc is incomplete there.  Users of Dune have to
assemble their boundary conditions in an ad hoc way.

If you want to iterate over boundary entities you have to iterate
over the elements.  On each element you have to iterate over the
intersections.  The intersection iterators will stop on intersections
with the boundary, and the method boundary() will return true
there.  That way you can identity boundary faces and vertices.

Hope this helps you some.  I'm afraid you've stumbled upon one
of the weak points of Dune.

Enjoy,
Oliver


> Is there also a Iterator that can iterate over boundary entities (vertices)?
>
>
> Best regards
> Arne Rekdal
>
>
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>   


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* Oliver Sander                ** email: sander at mi.fu-berlin.de        *
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