Patterns in a Two-Dimensional Annular Granular Layer

Patterns such as periodic subharmonic waves and kink-pairs are observed experimentally in a two-dimensional vertically vibrated granular layer located in an annular channel which has a sawtooth-shaped base. Using the thickness of the granular layer and external excitation as control parameters, we find the transitions between different patterns in the layer. The dependence of the kink-pair's velocity on the external excitation is revealed. The local velocity fields of the granular layer indicate that, in addition to horizontal transport in the layer, there is convection in the node area of a kink.