Item

Abstract

Equilibrium is a state of maximal entropy or disorder; it looks boring. In contrast,
systems maintained far from equilibrium exhibit a diversity of fascinating
behaviour including pattern formation and turbulence. These systems still pose
fundamental questions.
In this thesis we report on a study of a granular, far-from-equilibrium system
consisting of macroscopic, spherical particles conned in a narrow, cuboidal cell
with a square base and large aspect ratio. The cell is vibrated sinusoidally in the
direction perpendicular to the long sides. In previous work the system has been
shown to behave as a two-dimensional granular gas. If the number of particles
in the box exceeds a certain threshold, then we can observe several patterned
states upon varying the driving amplitude. The patterns are found to consist
of subharmonic standing waves reminiscent of Faraday waves in molecular uids.
We observe time-independent patterns as well as a spatiotemporally chaotic state
in which the pattern changes its shape rapidly. At higher driving amplitudes
impressive wave fronts sweep across the system and destroy the patterns. The
waves are replaced by a large-scale circulation if the amplitude is increased further.
These states show characteristics of turbulence. We ascertain that the system has
no characteristic length-scale after descending into the turbulent state.