Title: Dynamics of Horizontally Oscillating Granular Layers*

Author (Poster): Jerry Gollub, Haverford College

Abstract:

The onset and dynamics of flow in horizontally oscillating granular layers are compared to the behavior of inclined layers (avalanches) and previous experiments. The threshold non-dimensional acceleration for flow onset is shown to vary with layer depth in a way that is quite close to the behavior of the tangent of the critical angle of inclination in avalanche experiments. However, within the oscillation cycle, the dynamics is surprising: If the oscillating acceleration is slightly higher than is required to produce flow, then the flow velocity grows as soon as the inertial forces exceed zero in each cycle, but flow ceases long before the inertial forces return to zero, possibly due to the buildup of internal stresses. At higher accelerations, the motion is fluid-like over the entire cycle. *With C. Puls. Supported by NSF-DMR.