title: Onset of diffusive behavior in confined transport systems.
abstract: We investigate the onset of diffusive behavior in polygonal channels for disks of finite size, modeling simple microporous membranes. It is well established that the point-particle case displays anomalous transport, because of slow correlation decay in the absence of defocusing collisions. We investigate which features of point-particle transport survive in the case of finite-sized particles (which undergo defocusing collisions). A similar question was investigated by Lansel, Porter, and Bunimovich [Chaos 16, 013129 (2006)], who found that certain integrals of motion and multiple ergodic components, characteristic of the point-particle case, remain in "mushroom"-like systems with few finite-sized particles. We quantify the time scales over which the transport of disks shows features typical of the point particles, or is driven toward diffusive behavior. In particular, we find that interparticle collisions drive the system toward diffusive behavior more strongly than defocusing boundary collisions. We illustrate how, and at what stage, typical thermodynamic behavior (consistent with kinetic theory) is observed, as particle numbers grow and mean free paths diminish. These results have both applied (e.g., nanotechnological) and theoretical interest.
authors: Therapeutics Research Unit, School of Medicine, University of Queensland, Princess Alexandra Hospital, Brisbane 4102, Australia. o.jepps@uq.edu.au
authors: Owen G
authors: OG
authors: Jepps
authors: Carlo
authors: C
authors: Bianca
authors: Lamberto
authors: L
authors: Rondoni
mesh_terms: D001692:Biological Transport / Q000502:physiology*; D001704:Biopolymers / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry*; D002463:Cell Membrane Permeability / Q000502:physiology*; D003198:Computer Simulation; D004058:Diffusion; D008954:Models, Biological; D008956:Models, Chemical
chemical_list: D001704:Biopolymers