[Dune] UG grid - limit on grid size?

[Oliver Sander]

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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