2005/01/31 by Matthias Schröter, Daniel I. Goldman, Harry L. Swinney · 1 citation
Physics and Astronomy · #cond-mat.stat-mech
paper · pdf · doi:10.1103/physreve.71.030301
published as Phys. Rev. E 71, 030301(R) (2005) · published with minor changes
arxiv created 2005/03/31 · arxiv updated 2009/12/01
A statistical description of static granular material requires ergodic sampling of the phase space spanned by the different configurations of the particles. We periodically fluidize a column of glass beads and find that the sequence of volume fractions phi of post-fluidized states is history independent and Gaussian distributed about a stationary state. The standard deviation of phi exhibits, as a function of phi, a minimum corresponding to a maximum in the number of statistically independent regions. Measurements of the fluctuations enable us to determine the compactivity X, a temperature-like state variable introduced in the statistical theory of Edwards and Oakeshott [Physica A \bf 157, 1080 (1989)].