  Jamming and avalanche statistics are studied in a simulation of the discharge
of a polydisperse ensemble of disks from a 2-D silo. Exponential distributions
are found for the avalanche sizes for all sizes of the exit opening, in
agreement with reported experiments. The average avalanche size grows quite
fast with the size of the exit opening. Data for this growth agree better with
a critical divergence with a large critical exponent, as reported for 3-D
experiments, than with the exponential growth reported for 2-D experiments.
