[Dune] Parallel grid partitioning

[Rebecca Neumann]

Dear Eike,

when I worked with parallel ALU  I got much better results by changing 
the partitioning method of metis.
Therefore you need the file alugrid.cfg in your directory (you can find 
a copy in ALUGrid-1.23/misc/ ),
in the third line you can change the partitioning method from 11 to 12.
Using Metis also means, that you don't always get the same partitioning 
for the same grid,
in my experience I got the same partitioning in about 9 of 10 cases.
I don't know if it matters to you, but for me it was a bit confusing at 
first.
I am not sure about the order of vertices, but I think that doesn't matter.

Best,
Rebecca

On 12.10.2011 21:37, Eike Mueller wrote:
> Hi Andreas,
>
> ok, I'll try the default loadbalancing first, maybe that's already not 
> too far away from what I want, at the moment I'm still struggling as I 
> can't get METIS to work. Hopefully the partitioning will be reasonably 
> close to what I want, it should at least keep vertical columns 
> together and usually I have more elements going around the globe than 
> in the radial/vertical direction (ratio is about 16 to 1). Does the 
> order in which I insert the vertices/elements have any influence on 
> the outcome of the partitioning?
>
> Thanks,
>
> Eike
>
> On 12 Oct 2011, at 20:24, Andreas Dedner wrote:
>
>> Hi Eike,
>>
>> at the moment you do not have that amount of control on ALUGrids 
>> loadbalancing
>> strategy. So you can use the grid factory to setup the grid (on one 
>> processor) and then
>> call loadBalance but that will not lead to the partitioning you want. 
>> Unfortunately the
>> GridFactories concept does not really provide an interface for 
>> parallel grid setup so
>> repartitioning your grid and using the factory is not really 
>> supported. We have it on th
>> agenda to extend the grid factory for parallel grid construction but 
>> it we have not yet
>> fixed the interface accordingly.
>>
>> I am sorry I can not give you a more positive answer
>> (but it is always a good first step to get something done if somebody 
>> actually needs it...)
>>
>> Best
>> Andreas
>>
>>>>> Second, I'm setting up a spherical shell with ALUGrid (see [1]). 
>>>>> Again I want to keep vertical columns together and not split into 
>>>>> the radial direction, so the sphere should be covered with eight 
>>>>> patches of equal size.
>>>>> So far I only managed to get the serial ALUGridFactory to work, if 
>>>>> I run in parallel, do I have to do the decomposition myself and 
>>>>> call inserVertex() and insertElement() on the appropriate 
>>>>> processor or can I do the balancing afterwards? Or do I have to 
>>>>> insert all vertices/elements on the master node?
>>>>
>>
>>
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>
>
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