Oscillatory velocity in boundary layer over mobile sediment bed under asymmetric wave and current conditions  

作　　者：Xin Chen 

机构地区：[1]Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System,China Agricultural University,Beijing 100083,China [2]Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province,Changsha University of Science and Technology,Changsha 410114,China

出　　处：《Journal of Hydrodynamics》2021年第6期1242-1254,共13页水动力学研究与进展B辑（英文版）

基　　金：Projects supported by the National Natural Science Foundation of China(Grant Nos.41961144014,51836010);the Chinese Universities Scientific Fund(Grant No.2019TC133).

摘　　要：The oscillatory flow provides the major dynamic force for the mass and energy transport in estuary and coastal areas.An analytical approximate velocity formula is proposed to evaluate the oscillation in the boundary layer over the mobile sediment bed of the sheet flow induced by the asymmetric wave and current.The velocity formula consists of an oscillatory force part and a constant force part corresponding to the Navier-Stokes equation of the asymmetric oscillatory sheet flow over the mobile sediment bed.The mobile sediment bed is defined by an erosion depth formula with consideration of the phase lag,the acceleration and the flow asymmetry.The wave part includes the phase lead parameters from all components of the free stream velocity.The development of the wave part is affected by the current part through the erosion depth and the boundary layer thickness.The erosion depth,the roughness height and the boundary layer thickness of the mobile sediment bed are introduced into the current part without a transition area for the wave-current eddy viscosity.The current part is induced by the wave eddy viscosity within the boundary layer and influenced by the wave-current apparent roughness outside the boundary layer.The velocity profile and duration are evaluated by an approximate velocity formula through experiments for both asymmetric wave and wave-current cases.The oscillation feature in the boundary layer is illustrated by the approximate velocity formula through the asymmetric wave cases over the mobile sediment bed.

关 键 词：Analytical approximation asymmetric wave and current eddy viscosity mobile sediment bed oscillatory sheet flow 

分 类 号：TV139.2[水利工程—水力学及河流动力学] TV14