Windows-Yule C R K, Parker D J
School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Feb;87(2):022211. doi: 10.1103/PhysRevE.87.022211. Epub 2013 Feb 27.
The importance of the method of energy injection into a vertically vibrated granular bed was investigated using positron emission particle tracking. A comparison was made between two experimental systems. The first was driven by a flat base, the second by a base comprising a monolayer of spheres, each free to move in three dimensions but constrained to the bottom of the system, effectively randomizing energy transfer into the bed. The latter system exhibited more Gaussian velocity distributions, a more isotropic temperature, and a better approximation of molecular chaos than the former, behavior more akin to the idealized situation of white noise forcing than is generally observed in an experimental system.
