title: Bottlenecks in granular flow: when does an obstacle increase the flow rate in an hourglass?
abstract: Bottlenecks occur in a wide range of situations from pedestrians, ants, cattle, and traffic flow to the transport of granular materials. We examine granular flow across a bottleneck using simulations of monodisperse disks. Contrary to expectations but consistent with previous work, we find that the flow rate across a bottleneck actually increases if an obstacle is optimally placed before it. Using the hourglass theory and a velocity-density relation, we show that the peak flow rate corresponds to a transition from free flow to congested flow, similar to the phase transition in traffic flow.
authors.affiliation: School of Civil Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia. fernando.alonso@sydney.edu.au
authors.forename: F
authors.initials: F
authors.lastname: Alonso-Marroquin
authors.forename: S I
authors.initials: SI
authors.lastname: Azeezullah
authors.forename: S A
authors.initials: SA
authors.lastname: Galindo-Torres
authors.forename: L M
authors.initials: LM
authors.lastname: Olsen-Kettle
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D008956:Models, Chemical; D012212:Rheology / Q000379:methods*
chemical_list: D003102:Colloids