Experimental Studies on the Characteristics of Near-bottom Flow in the Current with Waves

本文的主要研究成果如下：（1）采用近底边界层的三层涡粘性模型，对波浪作用下水流中的定常流分量进行了理论分析。此外，给出了一种简单的方法来估计解析解中包含的重要参数。解析解与实验结果基本一致。(2)采用两层涡粘性模型，波浪边界层内涡粘性随离底高度成二次函数增加，边界层外涡粘性随离底高度成二次函数增加，得到了波浪作用下水流中波流分量的理论解。理论值和实验值基本一致。(3)由定常流分量和波浪流分量的理论解，得到了波浪流中剪应力的解析值。由剪应力的分析结果，阐明了底剪应力随波相的变化规律以及波浪运动对底剪应力的影响。(4)波浪边界层内外波流波流分量的相位差在底部最大。在本实验条件下，相位差的最大值在40 ~ 48 μ m之间。(5)在本实验条件下，波浪流中底部沉积物的再悬浮率比水流中的再悬浮率大20%~ 30%左右。在恒定流速下，底质再悬浮率随波高的变化大于随流速大小的变化。

The Summary of this research results is as follows :(1) The steady flow component in the current with waves was theoretically analyzed by using a three-layr eddy viscosity model near the bottom boundary layr. Moreover, a simple method to estimate the important parameters contained in the analytical solution was presented. The analytical solutions almost agreed with the experimental results.(2) The theoretical solution of the wave flow component in the current with waves was obtained by using a two-layr eddy viscosity model, in which the eddy viscosity in the wave boundary layr increased quadratically with the height above the bottom and that outside the wave boundary layr constant. The theoretical and experimental values almost agreed.(3) The analytical values of shear stress in the current with waves were obtained from the theoretical solutions of the steady and wave flow components. The variations of the bottom shear stress with wave phase and the influences of wave motion on the bottom shear stress were clarified from the analytical results of shear stress.(4) The phase difference of the wave flow component in the current with waves inside and outside the wave boundary layr was maximum at the bottom. The maximum value of phase difference ranged between 40ﾟ and 48ﾟ for the present experimental conditions.(5) The resuspension rate of the bottom sediment in the current with waves for the present experimental conditions was about 20% to 30% bigger than that in the current. The variations of the resuspension rate of the bottom sediment with the wave height under a constant velocity were bigger than those with the magnitude of velocity under a constant wave height.