[Dune] bad grids??

Oliver Sander sander at mi.fu-berlin.de
Mon Jun 11 11:19:17 CEST 2012

Hi Marco,
you can get rid of the five-vertex elements if you use red-green
refinement.  UGGrid will do that for you.  UGGrid also allows you
to reposition interior vertices using a non-interface setPosition

Am 11.06.2012 10:56, schrieb Marco Cisternino:
> Good morning,
> I would like to share with you a problem we have.
> We have already thought about the solution to it, but it's probably not
> feasible with dune+ALUGrid.
> That's why I ask your help, I hope anyone has already had the same
> situation.
> We start our finite volume calculation on a coarse grid generated by a
> mesh generator.
> We refine the grid in a standard way, dividing fathers. The results is
> that at the border between two different levels of refinement the
> children have the same face slope of the fathers and this means that at
> the leaf level the face slope of these cells change only when the father
> changes.
> This kind of grid causes oscillations in dynamical variables with a
> wavelength equal to the fathers grid step.
> We've also found out that moving the hanging nodes of the children out
> of the face of the father, using a parametrization, can cure this
> oscillations.
> The problem is that we can get elements with 5 faces ( starting with a
> 2D grid of quadrilaterals) we are not able to manage with ALUGrid.
> I imagine that almost the same situation can be obtained in the
> coarsening of a grid as the result of the elimination of a vertex...
> How did you deal with this kind of problem??
> Can you cure the oscillation with a discretization argument or the grid
> is the only way???
> Thanks a lot for any help.
> Best regards,
> Marco
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