Physics
Vortices in vibrated granular rods
Document Type
Article
Abstract
We report the experimental observation of vortex patterns in vertically vibrated granular rods. Above a critical packing fraction, moving ordered domains of nearly vertical rods spontaneously form and coexist with horizontal rods. The domains of vertical rods coarsen in time to form large vortices. We investigate the conditions under which the vortices occur by varying the number of rods, vibration amplitude, and frequency. The size of the vortices increases with the number of rods. We characterize the growth of the ordered domains by measuring the area fraction of the ordered regions as a function of time. A void-filling model is presented to describe the nucleation and growth of the vertical domains. We track the ends of the vertical rods and obtain the velocity fields of the vortices. The rotation speed of the rods is observed to depend on the vibration velocity of the container and on the packing. To investigate the impact of the direction of driving on the observed phenomena, we performed experiments with the container vibrated horizontally. Although vertical domains form, vortices are not observed. We therefore argue that the motion is generated due to the interaction of the inclination of the rods with the bottom of a vertically vibrated container. We also perform simple experiments with a single row of rods in an annulus. These experiments directly demonstrate that the rod motion is generated when the rods are inclined from the vertical, and is always in the direction of the inclination. © 2003 The American Physical Society.
Publication Title
Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
Publication Date
1-2003
Volume
67
Issue
3
First Page
6
ISSN
1063-651X
DOI
10.1103/PhysRevE.67.031303
Repository Citation
Blair, Daniel L.; Neicu, T.; and Kudrolli, A., "Vortices in vibrated granular rods" (2003). Physics. 135.
https://commons.clarku.edu/faculty_physics/135
Cross Post Location
Student Publications
