Experiments that illustrate anomalous and non-local transport

Abstract

In this work our focus is the related phenomena of anomalous diffusion and non-local transport. The former refers to physical systems in which the spreading of a solute does not exhibit the classic square root of time behavior; the later describes cases where the flux of a solute at a point is controlled by features at locations removed from that point. Two experimental systems that produce clear signals of anomalous diffusion and non-local transport are presented. The first measures the infiltration of fluid into an obstacle filled cavity. We show that when the obstacles are laid out in a fractal pattern the infiltration measure exhibits an anomalous diffusion behavior. The second experiment studies the steady state by-pass profile of a two-dimensional rice pile. We show that the pile's profile has a concave down curvature that, through modeling we argue, is a consequence of non-local transport.