[Dune] globalRefine and ALUGRID_SIMPLEX

[Dragan Vidovic]

Dear all,

I would like to draw your attention to the way the globalRefine
function works with ALUGRID_SIMPLEX in 3d. I define a simple unit cube
in a dgf file

DGF
Interval
0 0 0  % first corner
1 1 1  % second corner
1 1 1  % 1 cells in x and 1 in y direction

and I do globalRefine(Dune::DGFGridInfo<GridType>::refineStepsForHalf())
in the code. I would expect the result to be as if my dgf file was

DGF
Interval
0 0 0  % first corner
1 1 1  % second corner
2 2 2  % 2 cells in x and 2 in y direction

but it is not. Actually, in the grid made by globalRefine, four cells
stretch from the bottom to the top of the cube, which means that the
new cells were not made by simply dividing the old cells into eight
similar cells. This reduces the grid quality, and I believe it was not
intended.

I must admit that my installation is somewhat older - I'm using a SVN
version of Dune from 13. of November 2009, and Alugrid 1.1.14.

Cheers,

Dragan