Convection in deep vertically shaken particle beds. II. The relationship between convection and internal wave propagation

摘要

The convective motion in deep vertically shaken beds is not continuous but occurs only during a brief portion of a cycle that roughly repeats over three periods of vibration. The convection is coordinated by a series of waves that propagate through the bed, a compression wave formed as the flask's bottom pushes upward against the bottom of the bed, and two expansion waves: a Type 1 expansion wave that is the reflection of the compression wave and a Type 2 expansion wave that forms as the flask's bottom moves away from the bottom of the bed. Convection only is observed after Type 1 expansion wave has passed the convective zone, relaxing the stresses in the bed and leaving the particles free to move. However the convective motion is confined to the region above Type 2 wave and convection disappears as a Type 2 wave passes. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2996135]