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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.