School Seminars and Colloquia

Granular complexities: from everyday materials to the extraterrestrial kind

Complex Systems Seminar

by Antoinette Tordesillas and Maya Muthuswamy

Institution: Department of Mathematics & Statistics, University of Melbourne
Date: Fri 10th June 2005
Time: 3:15 PM
Location: Theatre 1, Old Geology Building, The University of Melbourne

Abstract: In 1987, Per Bak, Chao Taug, and Kurt Wiesenfeld published a now famous
paper in Physical Review Letters, proposing the theory of self-organized
criticality, in which they used an all-too-common sight - a sand pile - as
a paradigm for complex systems out of equilibrium (e.g. an outbreak of a
war, a stock market crash, forest fires). Sand, M&Ms, powders,
pharmaceutical pills, grains and other granular materials exhibit a vast
range of complex phenomena that defy our usual classification of matter
into a solid, liquid or gas. Take, for example, vacuum-packed coffee:
under pressure, it is a solid-like material as hard as a brick, but when
opened and poured into a container, it flows like water. In common with
other complex systems, the simplest unit in a granular assembly, i.e.
the interaction of two particles in contact, is well understood; the
complexity emerges from the collective behaviour of the whole assembly. In this talk, we will highlight challenges in our quest to develop
rheological models of dry granular assemblies using two methodologies:
micromechanical continuum theory and discrete element method. And if
that's not complex enough, wait till you see the challenges that await
those involved in the exploration and settlement of the all-granular lunar
and Martian surface!

For More Information: Emma Lockwood tel. 8344-1617 email: