On the dynamics of avalanches for 2D systems

Avalanches in a two-dimensional dry granular system, the rotating drum setup, are studied in detail. The distribution of angles at which avalanches initiate and terminate, as well as those for time between avalanches, are characterized. The results are analyzed assuming that the instantaneous surface angle of the pile is a stochastic Markov process. The macroscopic evolution equations for the average angle of the pile and its standard deviation are also studied. We comment on other variations of the experimental setup, such as having different effective gravity force.