A turbulent and suspended sediment transport model for plunging breakers

Extensive studies have suggested a high concentration of suspended sediment near the free surface induced by strong plunging breakers. However, prediction by models have not been successful because of the localized interactions among the plunging jet, turbulent production, and sediment movement. This study proposes a new calculation model for turbulent flow and suspended sediment transport in the surf zone. A numerical model was developed to simulate the flow and sediment motion in connection with plunging breakers in the surf zone. The Reynolds-Averaged NavierStokes (RANS) equations in two spatial dimensions were employed to simulate the flow field together with a k-ε model for the turbulence and the Volume of Fluid (VOF) method for multiple free-surface tracking. An advection-diffusion equation was used for the suspended sediment concentration with a bottom boundary condition following the reference concentration formulation. Performance of the suspended sediment transport model under plunging breaking waves were examined through the comparison with experimental data. Good agreement between the model and experimental data was obtained for the surface elevation and velocity, turbulent kinetic energy, eddy viscosity and suspended sediment concentration. The overturning waves, plunging jet and transport of high concentration of suspended sediment near the free surface are reproduced by the present model with selected fine mesh resolution. The study shows the applicability of the present model in the turbulent and suspended sediment dominated region induced by strong plunging breakers.