[Dune] UG grid - limit on grid size?

[Eike Mueller]

Hi Oliver,

this works, thanks a lot! After recompiling UG I can go up to 
64x64x16x6, but if I try 128x128x32x6 (~ 2^22, but again, it's a serial 
run) I now get this:

ERROR in InsertElement:   ==> NdElPtrArray_GetMemAndCheckIDs( ) ERROR: 
No memory for MGNDELEMBLK(theMG,j)
ERROR in InsertElement:  ERROR by calling NdElPtrArray_GetMemAndCheckIDs()
terminate called after throwing an instance of 'Dune::GridError'

I tried increasing the heap size in the uggrid construction

   uggrid = new Dune::UGGrid<3>(10000);

but I still get the same error message.

Cheers,

Eike

Oliver Sander wrote:
> Hi Eike!
> This is a known problem.  Please see the FAQ entry 4.2 on the dune homepage
> for an explanation and a workaround.
> Cheers,
> Oliver
> 
> Am 05.10.2011 14:23, schrieb Eike Mueller:
>> Dear Dune-list,
>>
>> I've used the UG grid factory to construct a UG grid on spherical shell
>> like this [1], basically following the instructions in [2]. It all works
>> fine, but fails (or rather hangs) once my grid reaches a certain size (I
>> found that if the number of elements is 25x25x25x6 = 93750 it's ok, but
>> for 26x26x26x6 = 105456 it fails). The number of nodes is about the same
>> as the number of elements. I do not get a runtime error message, but it
>> just hangs in
>>
>> uggrid = new Dune::UGGrid<3>;
>> uggrid = factory.createGrid();
>>
>> Now, I might be getting the memory allocation wrong (I've tried passing
>> a larger heapsize to to Dune::UGGrid<3> constructor), but I also saw
>> this discussion here [3] saying that there are limits on the size of the
>> UG grid that can be constructed (I do not compile with -DNDEBUG and this
>> is a serial run and from how I understand it the limit should be 2^32
>> elements in serial runs?).
>>
>> Basically, I've got a class called Cubedsphere, which has the private
>> data field
>>
>> Dune::GridFactory<Dune::UGGrid<3>> factory;
>> Dune::UGGrid<3>* uggrid;
>>
>> In the constructor I generate my grid vertices (I know the exact
>> expressions for the positions, so don't need to read them from file) by
>> first calling
>>
>> factory.insertVertex(vertex);
>>
>> for all vertices and storing their ids and positions (both as unsigned
>> ints) in a lookup table and then generating the elements from the
>> entries in the lookup table with
>>
>> factory.insertElement(cube,vertices);
>>
>> When all this is done I call
>>
>> uggrid = new Dune::UGGrid<3>;
>> uggrid = factory.createGrid();
>>
>> in the constructor and the class also has a method
>>
>> Dune::UGGrid<3>* getUGGrid() { return uggrid; };
>>
>> for returning a reference to the uggrid pointer.
>>
>>
>>
>> Thank you very much for any help,
>>
>> Eike
>>
>>
>>
>> [1] http://people.bath.ac.uk/em459/dune.html
>> [2]
>> http://www.dune-project.org/doc/doxygen/html/classDune_1_1GridFactory_3_01UGGrid_3_01dimworld_01_4_01_4.html 
>>
>>
>> [3]
>> http://www.dune-project.org/flyspray/index.php?do=details&task_id=250#comment2700 
>>
>>
>>
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