海底边界层水流结构及底移质搬运研究进展

FLOW STRUCTURE IN THE MARINE BOUNDARY LAYER AND BEDLOAD TRANSPORT:A REVIEW

海底边界层包括从床底至受其显著影响的水体之间的水层厚度 ,对海底动力过程 ,尤其是沉积物搬运及近海底化学物质输运有重要影响 ,不同的水动力 (潮流、波浪及浪流共同作用 )形成完全不同的边界层。边界层厚度与水流周期有关 ,但目前对其理解及计算公式并不统一 ,边界层内的流速分布与摩阻流速和床底糙率有关 ,目前已经发展了多种估算这两个参数的方法。对于边界层内的沉积物搬运率的计算 ,关键在于弄清沉积物在边界层内的沉降、起动的机制 ,确定其控制参数。

The marine boundary layer plays an important role in hydrodynamic and sediment dynamic processes(especially in bedload and chemical material transport).Various boundary layers with different flow structures are present due to different hydrodynamics,e.g.tidal currents,waves and their interactions.The thickness of the marine boundary layer (δ) is related to the flow period.There are a number of definitions of δ.The flow structure can be described using two boundary layer parameters,i.e.the fraction velocity and seabed roughness.A lot of algorithms have been developed to derive these parameters.For the estimation of bedload transport rate,semi empirical formulae are derived and calibrated.However,so far only limited data sets from in situ measurements within the marine boundary layer have been obtained.Hence,further studies are required on the boundary layer processes.