One dimensional drift-diffusion between two absorbing boundaries:   application to granular segregation
  Motivated by a novel method for granular segregation, we analyze the one dimensional drift-diffusion between two absorbing boundaries. The time evolution of the probability distribution and the rate of absorption are given by explicit formulae, the splitting probability and the mean first passage time are also calculated. Applying the results we find optimal parameters for segregating binary granular mixtures. 
Zeno Farkas and Tamas Fulop