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Seminar: Dr, Xiao Yu, UNC Institute of Marine Sciences
February 15, 2017 @ 3:30 pm - 4:30 pm
Seminar Title: Two-phase approach for sediment transport
Presenter Affiliation: UNC Institute of Marine Sciences
Summary: Sediment transport by turbulent flow occurs widely in nature and the modelling of sediment transport is very challenging because of the complex interactions between turbulent flow and particles, as well as particle-particle interactions. The two-phase model is shown to be able to model the complicated turbulent-particle and particle-particle interactions, and it depends on two dimensionless numbers, namely the sediment concentration and Stokes number (particle response time/turbulent time scale). Under sheet flow conditions on sandy beach, the sediment concentration is high and Stokes number is large, the kinematics of the fluid and sediment phases are strongly coupled. With RANS turbulent closure and kinetic theory, the Eulerian-Eulerian two-phase model can be applied to study sand transport under different flow conditions, and used as a diagnostic tool to evaluate widely used empirical and semi-empirical sediment transport formulas. For fine sediment transport in coastal regions, sediment concentration is typically dilute (particle-particle interaction is negligible) and the particle Stokes number is relatively small (much smaller than 1). Equilibrium Eulerian approach with turbulent resolving schemes is ideal, and can be used to study the interactions between flow turbulence and sediment particles. This model can be applied to study both the initial deposition and resuspension processes of fine sediment in coastal regions, and shown to be capable of investigating the underlying mechanisms of sediment transport under different flow conditions.