[petsc-users] Laplacian at infinity

Matthew Knepley knepley at gmail.com
Mon Sep 22 09:52:56 CDT 2014

On Mon, Sep 22, 2014 at 9:08 AM, Jed Brown <jed at jedbrown.org> wrote:

> Matthew Knepley <knepley at gmail.com> writes:
> > On Mon, Sep 22, 2014 at 7:36 AM, John Alletto <4bikerboyjohn at gmail.com>
> > wrote:
> >
> >> All,
> >>
> >> I am try to match some E&M problems with analytical solutions.
> >> How do I deal with infinity when using a uniform grid ?
> >>
> >
> > It depends on your problem. Keep making it bigger and see if you get
> > convergence.
> This is a way to assess error caused by the finite grid, but you can
> also use an analytic solution for that.  Using an asymptotic expansion
> for the boundary condition can be useful (esp. when there is nonzero
> charge in the domain, for example).  For wave propagation, look at
> perfectly matched layers (PML).

PML is the best option, although many codes simply use attenuation.


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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