Grain Dynamics in a Twodimensional Granular Flow.pdf

Grain Dynamics in a Two-dimensional Granular Flow S. Hørl¨uck and P. Dimon The Center for Chaos and Turbulence Studies The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark (To appear in Phys. Rev. E.) 0 We have used particle tracking methods to study the dynamics of individual balls comprising a 0 granular flow in a small-angle two-dimensional funnel. We statistically analyze many ball trajectories 0 to examine the mechanisms of shock propagation. In particular, we study the creation of, and 2 interactions between, shock waves. We also investigate the role of granular temperature and draw t parallels to traffic flow dynamics. c O PACS Numbers: 45.70.Mg 4 2 I. INTRODUCTION smaller length and time scales. This enables us to observe ] shock creation and interaction more closely. We can then t Density waves are known to propagate in a variety of compute the granular temperature and also traffic flow f o granular flow systems. For example, flows in funnels or curves. The paper is structured as follows. In Sec. II we s. hoppers can have slowly propagating density waves that describe the experimental setup and the particle tracking t may move up or down depending on sand properties and method. In Sec. III we study the properties of individual a m geometry [1]. They also occur in long pipes [2] and closed ball trajectories. In Sec. IV w