Biased Brownian Motion in Asymmetric Channel with Anisotropy

Kiwing To^1*, Wei-hsuan Tseng²

¹Institute of Physics, Academia Sinica, Taipei, Taiwan
²Department of Physics, National Taiwan Normal University, Taipe, Taiwan

* Presenter:Kiwing To, email:ericto@gate.sinica.edu.tw

We study the motion of a single millimeter size bead conned in a vertically vibrated quasi-two-dimensional asymmetric horizontal channel [PRE 94, 022902 (2016)]. The base of the channel is grooved along the channel axis so that the bead can acquire a horizontal impulse perpendicular to the longitudinal direction when it collides with the base. We find that the combination of asymmetric walls and anisotropic base can induce an effective net force exerting on the bead and lead to a finite current and a non-trival position probability distribution. In the meantime, the bead performs biased Brownian motion along the channel with both the diffusion constant and the drift velocity increases with vibration strength. These findings are consistent to the Fokker-Planck equation and the motion of the bead can be explained by the continuous time random walk model.

Keywords: Biased Brownian Motion, Asymmetric and Anisotropy, Fokker-Planck equation, Continuous time random walk model