[Dune] boundary id

[Oliver Sander]

Hi

> Hi,
> my view of boundary and domain ids:
> 1) at the moment domain ids defined for entiy 0 can be easily handle
>  using discrete functions since suitable mappers and iterators are
>  available so that I would suggest to keep everything as is in this
>  repect for 1.0

In my opinion, this is even the proper way to do it.  To me, domain
ids are not an intrinsic part of a grid but external data, and
should be handled as such.

> 2) boundary ids are a bit different since we have no iterators and
>   no index sets for boundaries - in fact no concept of boundaries in
>   Dune. It would be nice to at least be able to identify boundaries
>   without having to rely on world coordinate information. This is
>   why we introduce boundaryIDs for the boundary intersection. The
>   semantics is - as I understand it:
>   For each boundary intersection on the macro grid we can define an
>   id (>0?). During refinement we have: if a boundary intersection I
>   lies in a boundary intersection I_0 then it has the same boundary id
>   as id...

I agree that it would be nice to have proper boundary handling.  But
I don't think that it is a good idea to add more intermediate 
functionality two weeks before creating a release branch.  Also,
personally, I do not have the resources to do the necessariy
adaptations in UGGrid.

--
Oliver

> Alberta/Alu work exactly in this way and the DGF parser can handle this
> approach as well. YaspGrid only assignes ID for each whole face of the
> domain. UG only returns a 1.
>
> Andreas
>
> Oliver Sander wrote:
>> Hi Andreas!
>> I would say that this is a definite post-1.0 feature.  In fact,
>> looking at the documentation of boundaryId I don't quite understand
>> what it is supposed to do precisely.  Hence I can't tell how
>> difficult it would be to build that feature in UGGrid.
>>
>> Cheers,
>> Oliver
>>
>> ************************************************************************
>> * Oliver Sander                ** email: sander at mi.fu-berlin.de        *
>> * Freie Universität Berlin     ** phone: + 49 (30) 838 75217           *
>> * Institut für Mathematik II   ** URL  : page.mi.fu-berlin.de/~sander  *
>> * Arnimallee 6                 ** -------------------------------------*
>> * 14195 Berlin, Germany        ** Member of MATHEON (www.matheon.de)   *
>> ************************************************************************
>>
>> ---------- Forwarded message ----------
>> Date: Mon, 11 Dec 2006 19:30:13 +0100
>> From: Andreas Dedner <dedner at mathematik.uni-freiburg.de>
>> To: Oliver Sander <sander at mi.fu-berlin.de>
>> Subject: boundary id
>>
>> Hallo Oliver,
>>
>> ich wollte nachfragen, wie schwierig es jetzt noch waere
>> die boundary ids in UG einzubauen. Du hattest irgentwann
>> makl gesagt, so ein Konzept gaebs in UG ohnehin...
>> Gruss Andreas
>>
>>
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