Re: Verify and comment, please.

[Ron Ebert <ebert@CITRUS.UCR.EDU>]

At 02:10 PM 2/1/99 -0500, you wrote:
> I seem to recall a PRL within the last decade entitled something like "Why
> Brazil nuts are always at the top". The essence of the article was an
> explanation of why larger particles in a mixture tend to work their way to
the
> top surface.
>
> Sorry I don't have a citation.
>
> Tim Sullivan
> sullivan@kenyon.edu

I don't have a PRL reference at hand, but I do have a news article about
this in the September 1993 issue of Scientific American (page 24). James B.
Knight, et al., built a test cylinder to study the movement of different
sized beads when the cylinder is shaken or tapped. They found that a
convection flow of beads was set up, with a fountain-like flow up through
the cylinder's center and a return flow back down in a thin layer along the
cylinder wall. The girth of the upward flow easily accommodates larger
beads, but the large beads cannot be swept into the thin layer along the
cylinder wall.


Ron Ebert
UCR Physics Department
ron.ebert@ucr.edu
http://phyld.ucr.edu