[Dune] Maximal level difference

[Martin Nolte]

Hi Carsten,

from my point of view, there is not reason not to add this to dune/grid/utility.

I'm not sure, though, that this code really enforces the requested maximum
difference between neighbor levels. The reason is that marking for coarsening
is only an indicator; the grid does not have to coarsen the element. Marking
for refinement force the grid to refine, but, due to implicit rules within the
grid, the element might actually be refined multiple times, resulting in a
potentially higher difference than requested.

For the above mentioned problems, it might be better to put the code into
UGGrid directly. Then you definitely know what the grid does with your markers.

Best,

Martin

On 11/29/2010 02:44 PM, Carsten Gräser wrote:
> Sorry, I forgot another issue regarding this:
> 
> Am 29.11.2010 14:35, schrieb Carsten Gräser:
>> Dear dune,
>> in dune-subgrid we implemented a simple method to automatically
>> add refinement marks and remove coarsening marks such that
>> the level of neighboring elements differs at most by a user
>> defined number. (ALUGrid e.g. does this internally).
>>
>> As someone asked for this functionality in UGGrid I extracted
>> this using the grid interface only. This might also be helpfull
>> for other third party grid implementations.
>>
>> Are there any objections to add this to dune/grid/utility?
> 
> We could also add a method
> 
>   setMaxLevelDifference(unsigned int level)
> 
> to UGGrid and call the utility-function from within
> UGGrid::preAdapt() internally. On the one hand this
> would make it a little easier to write portable code,
> on the other hand it's essentially syntactic candy
> that blows up the UGGrid interface (by one method).
> 
> Furthermore I'm not sure if the name is good. Currently
> the function is called
> 
>   template<class GridType>
>   static void enforceNeighborLevelDifference(GridType& grid, int maxLevelDiff);
> 
> Any opinions?
> 
> Regards,
> Carsten
> 
> PS: You can find the full implementation attached.
> 
> 
> 
> 
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-- 
Martin Nolte <nolte at mathematik.uni-freiburg.de>

Universität Freiburg                                   phone: +49-761-203-5630
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