Turbulent Bursting-Based Model Applied to Prediction of Suspended Sediment Concentration

Abstract

The eddy diffusivity of suspended sediment is a key element in determining the concentration profile of suspended sediment in open-channel flows at equilibrium state. Traditionally, the eddy diffusivity has been related to the eddy viscosity by using the empirical coefficient β. However, the literature study reveals that the coefficient β is quite uncertain. This paper presents applications of the turbulent bursting-based model by Cao et al. (1996) to the prediction of suspended sediment concentration. The model predicts the concentration profile using the vertical turbulent intensity, mean duration of turbulent bursts, and particle relaxation time. The model is applied to two sets of experimental data: open-channel flow over a rough bed and open-channel flow with submerged vegetation. In the open-channel flow over a rough bed, it is found that the eddy diffusivity and concentration profiles by the turbulent bursting-based model are very similar to the results by the modified parabolic formula by Lyn (1993). In the open-channel flow with submerged vegetation, the eddy diffusivity profile is predicted by the turbulent bursting-based model, and the sensitivity of particle size is investigated. The distribution of suspended sediment is obtained and discussed through comparisons with the result by the numerical model and with the Rousean