FRACTIONAL DYNAMICS IN RANDOM VELOCITY-FIELDS

We develop an iterative approach, from which an exact systematic calcu lation of the moments of the probability density of test particles, un der a generalized Fickian evolution and in the presence of a stratifie d random velocity field, can be calculated. The type of fractional dif fusion-advection equation studied is useful for transport in anisotrop ic and heterogeneous media, Our method stresses the relevance of the c oupling between anomalous diffusion and convection by stratified rando m velocity fields. [S0031-9007(98)07342-6].