Author(s): Ruidong An
Linked Author(s):
Keywords: Hyperpycnal flow; Turbidity current; Algebraic slip; ASM model
Abstract: Turbidity hyperpycnal flows are currents driven by excess density caused by suspended sediment of flood-induced turbid river water, which are believed to deliver the majority of sediment to the reservoirs for deposition. By introducing the definition of slip velocity between water and turbidity current, the Algebraic Slip Mixture model has been used and applied. The governing equations including momentum, continuity and algebraic velocity expressions were used to simulate two-dimension flood-induced turbidity hyperpycnal flows in this paper. To check the accuracy of the numerical model, parallel test experiments producing sixteen successfully runs in a multiphase laboratory tank were also carried out. Including velocity, inflow discharge, suspended sediment concentrations, grain size were measured to determine the influence of the variability in characteristics and hydrodynamic impact of such currents. The Reynolds number and densimetric Froude number are used to describe the occurrence condition of turbidity currents, which the currents were successfully produced with the Re number of 3167-13240 and densimetric Froude number of0.53-2.96. It is also shown that the plunging position of the currents can be identified by the maximum vertical velocity gradient, the flow front thickness increases by distance and higher sediment concentration associated with increased reflux around front. Such phenomena have been observed and proved in both experiment and simulated numerically, which provide a valuable method to predict the sediment transportation of turbidity currents with the desired accuracy for better planning and design of a reservoir.
Year: 2009