Driven Brownian transport through arrays of symmetric obstacles

Abstract

We numerically investigate the transport of a suspended overdamped Brownian particle which is driven through a two-dimensional rectangular array of circular obstacles with finite radius. Two limiting cases are considered in detail, namely, when the constant drive is parallel to the principal or the diagonal array axes. This corresponds to studying the Brownian transport in periodic channels with reflecting walls of different topologies. The mobility and diffusivity of the transported particles in such channels are determined as functions of the drive and the array geometric parameters. Prominent transport features, like negative differential mobilities, excess diffusion peaks, and unconventional asymptotic behaviors, are explained in terms of two distinct lengths, the size of single obstacles (trapping length), and the lattice constant of the array (local correlation length). Local correlation effects are further analyzed by continuously rotating the drive between the two limiting orientations.

Manipulating chiral microswimmers in a channel

“…This situation occurs at low noise (both thermal and orientational) when, upon increasing the torque, the particle tends to accumulate against the walls [23,[29][30][31] with tangential velocities approaching ±v 0 . Optimal anomalous rectification [30] is thus established under the regime of strong chirality, | |τ θ 1 or l θ R , and high Péclet numbers, Pe 1, with Pe ≡ v 2 0 | |/D 0 .…”

Front propagation in channels with spatially modulated cross section

“…Experimental [21,22] and theoretical studies [24,25] on particle transport in micro-domains with obstacles [54,55] and/or small openings revealed that Brownian motion in such systems exhibits non-intuitive features like a significant suppression of particle diffusivity [23,27,56]. Numerous research activities in this topic led to the development of an approximate description of the diffusion problem -the Fick-Jacobs approach [57,58].…”

Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

“…The capability of such devices for separation of particles is rooted in the effect of entropic rectification, i.e., the rectification of motion caused by broken spatial symmetry caused by asymmetric variations of the accessible local volume [18][19][20]. The transport in channels with periodically varying cross-section exhibits peculiar transport phenomena [21][22][23][24][25][26] which can be treated by means of the so-termed Fick-Jacobs formalism and its generalizations [1,[27][28][29][30][31][32][33][34][35][36]. Figure 1.…”