Particle inertia effect on sediment dispersion in turbulent open-channel flows

Particle inertia effect plays a significant role in sediment dispersion which has not been fully elucidated. In this paper, the profound effect of particle inertia on the sediment dispersion was analyzed. The theoretical expression for the drift velocity based on the two-phase mixture theory in turbulent open channels is firstly introduced. The influence of particle inertia on sediment dispersion was investigated through three different aspects including vertical dispersion, motion, and flux properties based on the drift velocity. Results show that the dispersion of suspended sediment in turbulent open-channel flows is affected by three major processes including turbulence of water sediment mixtures, particle random motion, and collisions among particles, of which the contributions of particle turbulence and collisions to the sediment dispersion are remarkable for particles of high inertia. With respect to the vertical mean velocity and sediment flux, it shows that the predictive results agree well with the measurements when the term of particle inertia is considered. As a result, particle inertia considerably affects the behavior of suspended sediment. In particular, the influence of inertia must be accounted for in circumstances of flows laden with high-inertia particles.