Sheet Flow Under Nonlinear Waves and Currents

Experiments were conducted on initiation and transport rate of sheet flow under asymmetric oscillations. Values of net sand transport rates under asymmetric oscillations and superimposed currents were also measured. In this paper, based on physical interpretations, a new parameter representing the observed transport mechanism is derived. Using this parameter a general transport formula is then presented and applied to estimating the net transport rate and its direction; fairly good agreement with the experimental results is observed. It is shown that the newly introduced parameter together with the sediment Reynolds number can fairly well express the inception of sheet flow.