Density fluctuations in vibrated granular materials

@article{citeulike:1360909, abstract = {We report systematic measurements of the density of a vibrated granular material as a function of time. Monodisperse spherical beads were confined to a cylindrical container and shaken vertically. Under vibrations; the density of the pile slowly reaches a final steady-state value about which the density fluctuates. We have investigated the frequency dependence and amplitude of these fluctuations as a function of vibration intensity Γ. The spectrum of density fluctuations around the steady state value provides a probe of the internal relaxation dynamics of the system and a link to recent thermodynamic theories for the settling of granular material. In particular; we propose a method to evaluate the compactivity of a powder; first put forth by Edwards and co-workers; that is the analog to temperature for a quasistatic powder. We also propose a stochastic model based on free volume considerations that captures the essential mechanism underlying the slow relaxation. We compare our experimental results with simulations of a one-dimensional model for random adsorption and desorption.}, author = {Nowak, Edmund R. and Knight, James B. and Ben-Naim, Eli and Jaeger, Heinrich M. and Nagel, Sidney R. }, citeulike-article-id = {1360909}, doi = {10.1103/PhysRevE.57.1971}, journal = {Physical Review E}, keywords = {density, fluctuation, grains}, month = {February}, number = {2}, pages = {1971+}, posted-at = {2008-04-27 00:55:38}, priority = {2}, publisher = {American Physical Society}, title = {Density fluctuations in vibrated granular materials}, url = {http://dx.doi.org/10.1103/PhysRevE.57.1971}, volume = {57}, year = {1998} }

TY - JOUR ID - citeulike:1360909 L3 - citeulike-article-id:1360909 TI - Density fluctuations in vibrated granular materials JF - Physical Review E VL - 57 IS - 2 SP - 1971 PB - American Physical Society N2 - We report systematic measurements of the density of a vibrated granular material as a function of time. Monodisperse spherical beads were confined to a cylindrical container and shaken vertically. Under vibrations; the density of the pile slowly reaches a final steady-state value about which the density fluctuates. We have investigated the frequency dependence and amplitude of these fluctuations as a function of vibration intensity Γ. The spectrum of density fluctuations around the steady state value provides a probe of the internal relaxation dynamics of the system and a link to recent thermodynamic theories for the settling of granular material. In particular; we propose a method to evaluate the compactivity of a powder; first put forth by Edwards and co-workers; that is the analog to temperature for a quasistatic powder. We also propose a stochastic model based on free volume considerations that captures the essential mechanism underlying the slow relaxation. We compare our experimental results with simulations of a one-dimensional model for random adsorption and desorption. KW - density KW - fluctuation KW - grains AU - Nowak, Edmund AU - Knight, James AU - Ben-Naim, Eli AU - Jaeger, Heinrich AU - Nagel, Sidney PY - 1998/02// UR - http://dx.doi.org/10.1103/PhysRevE.57.1971 ER -