Modes of response in horizontally vibrated granular matter
The James Franck Institute and The Department of Physics, The University
of Chicago 5640 S. Ellis Ave, Chicago, IL 60637, USA
Accepted: 26 July 2000
When forced by horizontal vibrations, granular material responds over a wide range of time scales. These include rapid shearing, harmonic response, period-doubling and long-time convection. Using high-speed video imaging and analysis, we map out the corresponding two-dimensional velocity fields. The presence of a free surface parallel to the shear direction and the fact that gravity acts perpendicularly to that direction lead to a decoupling of the system into two horizontal layers of different character. We observe this decoupling on all time scales, implying that, in contrast to vertically excited systems, models without internal degrees of freedom are unable to describe the observed response modes.
PACS: 45.70.-n – Granular systems / 47.50.+d – Non-Newtonian fluid flows / 45.50.-j – Dynamics and kinematics of a particle and a system of particles
© EDP Sciences, 2000