The present approach, which considers a diluted sediment suspension as a perturbation to a clear-water flow, permits a direct comparison of the energetics of turbulent sediment-laden and clear-water open-channel flows of constant slope and depth. On the basis of the Boussinesq approximation to the momentum equations for the flow with sediment in suspension and the Navier-Stokes equations for the clear-water flow, a depth-averaged equation for the change in turbulence energy dissipation rate and an equation for the flow energy budget are obtained. From the analysis of these equations it becomes clear that the presence of the suspension affects the distribution of energy in the flow; also, the turbulence kinetic energy can increase, decrease, or remain the same depending on the sediment loading conditions, and its rate of dissipation can increase, decrease, or remain the same depending on the magnitude of the flow hydraulic parameters relative to that of the loading conditions. These findings provide additional insight into the energetics of these complex flows, agree qualitatively with experimental data, and complement available models.¿ 1997 American Geophysical Union |