Granular Brownian motors: role of gas anisotropy and inelasticity

Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Apr;87(4):040201. doi: 10.1103/PhysRevE.87.040201. Epub 2013 Apr 3.

Abstract

We investigate the motion of a two-dimensional wedge-shaped object (a granular Brownian motor), which is restricted to move along the x axis and cannot rotate as gas particles collide with it. We show that its steady-state drift, resulting from inelastic gas-motor collisions, is dramatically affected by anisotropy in the velocity distribution of the gas. We identify the dimensionless parameter providing the dependence of this drift on shape, masses, inelasticity, and anisotropy: The anisotropy leads to dramatically enhanced drift of the motor, which should easily be visible in experimental realizations.