THE CONSTANT DISPLACEMENT SCHEME FOR TRACKING PARTICLES IN HETEROGENEOUS AQUIFERS

Simulation of mass transport by particle tracking or random walk in hi ghly heterogeneous media may be inefficient from a computational point of view if the traditional constant time step scheme is used. A new s cheme which adjusts automatically the time step for each particle acco rding to the local pore velocity, so that each particle always travels a constant distance, is shown to be computationally faster for the sa me degree of accuracy than the constant time step method. Using the co nstant displacement scheme, transport calculations in a 2-D aquifer mo del, with nature log-transmissivity variance of 4, can he 8.6 times fa ster than using the constant time step scheme.