[CIG-MC] SUPG method in CitcomS

Louise Kellogg kellogg at ucdavis.edu
Mon Apr 9 08:30:47 PDT 2012

Hi Matt:

As you note, the Lenardic & Kaula filter was designed for the sharp interfaces found in dealing with 2 materials. It's not really suitable for temperature; it wasn't designed for that, and would have the disadvantages noted by Jed.  


On Apr 7, 2012, at 6:35 AM, Matthew Knepley wrote:

> On Sat, Apr 7, 2012 at 1:41 AM, Jed Brown <five9a2 at gmail.com> wrote:
> On Fri, Apr 6, 2012 at 22:20, Matthew Knepley <knepley at mcs.anl.gov> wrote:
> Can't you also do WENO reconstruction on an FEM solution?
> It's much less natural and rarely done in practice.
> Okay, that was not how it was explained to me. Is it like a Laplacian filer (which would sharpen edges)? I don't see how this would reduce oscillation,
> although I guess it could result from the solve for the conservation requirement.
> Look at the algorithm, it is a discrete interface sharpening filter.
> http://www.agu.org/pubs/crossref/1993/92JB02858.shtml
> It clips values that are greater than 1 or less than 0, tracking the maximum over/undershoot. Values inside the bounds of that over/undershoot are then pressed out to 1 and 0 respectively. Then the remaining conservation error is distributed to all cells that are not identically 0 or 1. I don't see any way that this is sensible for thermodynamics.
> It will get rid of oscillation and conserve the quantity (looks a little like FCT), but the 0,1 bounds make no sense to me
> for energy. For concentration (as in the paper), they are natural.
>     Matt
> -- 
> 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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Louise Kellogg
Professor, Department of Geology
One Shields Avenue, University of California, Davis, CA 95616
Phone: (530)752-3690

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