Convective and diffusive particle transport in channels of periodic cross-section: comparison with experiment

Abstract

This paper compares the results of a theoretical model with published experimental data investigating the potential use of a drift ratchet as a particle transport device. The drift ratchet of interest here involves the oscillation of a particle-laden fluid through a periodically shaped tube, combined with an exploitation of the Brownian motion of the small particles. Our theoretical results support the experimental evidence that, at these scales, the ratchet effect is not the predominant mechanism for facilitating particle transport. Rather, the tube geometry (but not orientation) and the form of the applied oscillating pressure gradient are the primary characteristics which determine the effectiveness of a device for particle transport. In particular, we find that transport is enhanced in a saw-tooth tube in comparison with a straight, cylindrical tube.