Date of this Version
Physical Review E
The dynamics of one and two identical spheres rolling in a nearly levitating upflow of air obey the Langevin equation and the fluctuation-dissipation relation [Ojha et al. Nature (London) 427, 521 (2004); Phys. Rev. E 71, 016313 (2005)]. To probe the range of validity of this statistical mechanical description, we perturb the original experiments in four ways. First, we break the circular symmetry of the confining potential by using a stadium-shaped trap, and find that the velocity distributions remain circularly symmetric. Second, we fluidize multiple spheres of different density, and find that all have the same effective temperature. Third, we fluidize two spheres of different size, and find that the thermal analogy progressively fails according to the size ratio. Fourth, we fluidize individual grains of aspherical shape, and find that the applicability of statistical mechanics depends on whether or not the grain chatters along its length, in the direction of airflow.
© 2005 American Physical Society. You can view the original article at: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.72.031305
Abate, A. R., & Durian, D. J. (2005). Partition of Energy for Air-Fluidized Grains. Physical Review E, 72 (3), 031305-1-031305-7. http://dx.doi.org/10.1103/PhysRevE.72.031305
Date Posted: 13 October 2017
This document has been peer reviewed.