近底层潮流速分布模式比较

Comparative study on the modeling of tidal current velocity profile in near-bottom boundary layers

考虑到潮流运动的非恒定性和非线性特征,基于潮流雷诺应力分布式,应用Prandtl混合长度和von Karman自相似理论,并结合潮流运动方程,推导了近底层潮流速垂向分布的双对数模式。然后,将该分布模式应用于英国大陆南部西Solent水道和江苏岸外西洋海域流速的实测资料,并与对数线性分布的计算成果相比较,获得了比较满意的结果。最后,对几种分布模式进行了讨论和比较,结果表明:在近岸水域采用对数或对数线性流速分布模式计算摩阻流速和粗糙高度往往会带来较大的偏差,双对数模式能使计算的结果更为合理。

A double-logarithmic velocity profile model （DLVPM） for tidal currents in near-bottom boundary layers is established. The DLVPM is achieved on the bases of the hydrodynamic equations for nonlinear unsteady tidal currents and the vertical distribution of Reynolds stresses, together with the Prandtl＇ s mixing length theory and the von Karman＇s self-similarity hypothesis. The DLVPM is applied in the west Solent a narrow channel between the Isle of Wight and the southern mainland of England and the Xiyang estuary out of Jiangsu coastlines in eastern China. The simulated tidal current velocity profiles are compared to the observations with satisfactory results. A comparative study is then carried out to evaluate the performances of three different velocity profile models including logarithmic, logarithmic linear and DLVPM. The result shows that both friction velocity and roughness height can be better simulated using DLVPM compared to another two simulations in the two model applications.