Title: Growing length scale in gravity-driven dense granular flow

Author (Talk): Shubha Tewari, Mount Holyoke College

Abstract:

We discuss simulations of a two-dimensional, dense, bidisperse system of inelastic hard disks falling down a vertical tube under the influence of gravity. We examine the approach to jamming as the opening at the base is made narrower and the average flow of particles down the tube slows. We define coarse-grained velocity and stress fields and focus on the central, 'plug flow' region of the tube where the average flow velocity stays constant. Using two point temporal and spatial correlation functions, we find that fluctuations in both velocity and stress become increasingly correlated as the system approaches jamming. We extract an increasing length scale and time scale from these correlations, and show that they exhibit power law behavior as a function of decreasing flow velocity.