[petsc-dev] Ghost values in sieve

[Matthew Knepley]

On Thu, Aug 23, 2012 at 12:26 PM, Chris Eldred <chris.eldred at gmail.com>wrote:

> Yes- I am implementing the TriSK scheme
> (www.mmm.ucar.edu/people/skamarock/Ringler_et_al_JCP_2009.pdf) on
> arbitrary Voronoi meshes. In order to do wind/flux reconstruction at
> the cell edges, it needs to know about the edges of adjacent cells-
> which are outside of closure(p) U star(p).


Great! Stuff that cannot be done with that structured crap. However, from
quickly looking at
the paper, there is nothing beyond the neighbors, so we can reuse the code
from
Jacobian preallocation. If you could tell me exactly what adjacency you
need, we might be
able to do it even more simply.

   Matt


> On Thu, Aug 23, 2012 at 11:16 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> > On Thu, Aug 23, 2012 at 12:12 PM, Chris Eldred <chris.eldred at gmail.com>
> > wrote:
> >>
> >> Thanks- that helps a lot. If I need stencils that are larger than
> >> closure(p) U star(p) (for a higher-order finite difference method, for
> >> example), I assume that I need to create my own PetscSF's that
> >> describe which points need to be ghosted?
> >
> >
> > Is this still a fully unstructured method? The Sieve formalism doesn't
> give
> > you a very efficient way to do this for structured or semi-structured
> grids.
> >
> > Even so, if wider stencils are to be supported, I think it should be
> > implemented within the library. Doing it outside with the current
> > infrastructure is going to be quite a rabbit hole.
> >
> >>
> >> Is there some documentation or example code that explains the theory
> >> behind star forests?
> >
> >
> > Docs for the basic operations:
> >
> > http://59A2.org/files/StarForest.pdf
>
>
>
> --
> Chris Eldred
> DOE Computational Science Graduate Fellow
> Graduate Student, Atmospheric Science, Colorado State University
> B.S. Applied Computational Physics, Carnegie Mellon University, 2009
> chris.eldred at gmail.com
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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