title: Growing length scale in gravity-driven dense granular flow.
abstract: We report 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 average flow of particles down the tube is slowed by making the outlet narrower. Defining coarse-grained velocity and stress fields, we study two-point temporal and spatial correlation functions of these fields in a region of the tube where the time-averaged velocity is spatially uniform. We find that fluctuations in both velocity and stress become increasingly correlated as the system approaches jamming. We extract a growing length scale and time scale from these correlations.
authors.affiliation: Department of Physics, Mount Holyoke College, 50 College Street, South Hadley, Massachusetts 01075, USA. stewari@mtholyoke.edu
authors.forename: Shubha
authors.initials: S
authors.lastname: Tewari
authors.forename: Bidita
authors.initials: B
authors.lastname: Tithi
authors.forename: Allison
authors.initials: A
authors.lastname: Ferguson
authors.forename: Bulbul
authors.initials: B
authors.lastname: Chakraborty