Abstract
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 of postfluidized states is history independent and Gaussian distributed about a stationary state. The standard deviation of exhibits, as a function of , a minimum corresponding to a maximum in the number of statistically independent regions. Measurements of the fluctuations enable us to determine the compactivity , a temperaturelike state variable introduced in the statistical theory of Edwards and Oakeshott [Physica A 157, 1080 (1989)].
- Received 4 January 2005
DOI:https://doi.org/10.1103/PhysRevE.71.030301
©2005 American Physical Society