Sediment transport in the saltation regime.

We present a study of sediment transport in the creeping and saltation regimes. In our model, a bed of particles is simulated with the conventional event-driven method. The particles are considered as hard disks in a two-dimensional domain with periodic boundary conditions in the horizontal direction. The flow of the fluid over this bed of particles is modeled by imposing a force on each particle that depends on the velocity of the fluid at its height above the bed. We consider two velocity profiles for the fluid, parabolic and logarithmic. The first one models laminar flow and the second corresponds to turbulent flow. For each case we investigate the behavior of the saturated flux. We find that for the logarithmic profile, the saturated flux shows a quadratic increase with the strength of the flow, and for parabolic profile, a cubic increase. The velocity distribution functions are used to interpret the results.