J. Phys. I France 4 (1994) 507-514
Density waves in granular flow: a kinetic wave approachJysoo Lee and Michael Leibig
HLRZ-KFA Jülich, Postfach 1913, W-5170 Jülich, Germany
(Received 15 November 1993, received in final form 16 December 1993, accepted 3 January 1994)
It was recently observed that sand flowing down a vertical tube sometimes forms a traveling density pattern in which a number of regions with high density are separated from each other by regions of low density. In this work, we consider this behavior from the point of view of kinetic wave theory. Similar density patterns are found in molecular dynamic simulations of the system, and a well defined relationship is observed between local flux and local density - a strong indicator of the presence of kinetic waves. The equations of motion for this system are also presented, and they allow kinetic wave solutions. Finally, the pattern formation process is investigated using a simple model of interacting kinetic waves.
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