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An application of two-phase 1DV model in studying sedimentary processes on an erosional mudflat at Yangtze River Delta, China

Xu, Chunyang, Dong, Ping
Frontiers of earth science 2017 v.11 no.4 pp. 715-728
equations, mixing, models, momentum, prediction, river deltas, sediments, shear stress, suspended sediment, turbulent flow, China, Yangtze River
A two-phase flow model for predicting sedimentation processes under wave and current conditions is presented. The model is based on solving the one-dimensional continuity and momentum equations for both fluid and solid phases through water column (1DV). The standard mixing length model is modified to take into account the buoyancy effect due to the gradient of suspended sediments near the seabed. The model is applied to study sedimentation processes on an erosional mudflat in the Yangtze River Delta, China, and intra-tide variations of flow properties and mud concentration are predicted and compared with field measurements. It was found that it is necessary to include the wave-induced shear stress in determining sediment erosion and the existence of a fluid mud layer can significantly influence both the flow structure and the distribution of sediment concentration in the water column. The turbulence dissipation induced by the fluid mud layer has the effect of increasing the duration of re-suspension during the early stage of the ebb. The overall good agreement between measured data and model results demonstrates the capability of the model.