含植物明渠紊流流速分布无量纲化方法及流动分区

基于流速分布曲线的几何特点，提出一种新的无量纲化方法，结合水槽实验数据的回归分析，对含植物明渠紊流流速分布律及流动分区进行了研究。基于流速梯度变化率的特点，确定两个特征高度，采用特征高度、特征高度位置处的流速、水深、最大流速4个变量定义了新的无量纲流速和高度，对实验得到的流速数据进行无量纲化处理，进一步拟合得到流速分布律。结果表明，提出的无量纲流速在自由水面附近呈对数分布，对数分布律区域以下到床面的区域可用4段函数表示。根据分布律适用的区域明确流动分区边界，发现边界高度与特征高度并不重合，但和混合层的上下边界近似相等。与其他研究的对比表明，提出的无量纲化方法和流速分段函数分布律以及流动分区对速度描述有效，具有较好的适用性。

Dimensionless method for velocity distribution in vegetated open channel turbulent flows and flow sub-division

Based on the geometric characteristics of the velocity profile, a new dimensionless method was proposed and combined with the regression analysis of the flume experimental data, the vertical velocity distribution law and turbulent flow sub-division in vegetated open channel were presented. According to the characteristics of variation rate of velocity gradient, two characteristic heights are determined. New dimensionless velocity and height are defined by the characteristic heights and corresponding velocities, water depth and maximum velocity, and the velocity distribution law is further obtained by the dimensionless experimental velocity data. The results show that the proposed dimensionless velocity is logarithmically distributed near the free water surface, and in the region between the logarithmic law zone and bed, it can be represented by a four-piecewise function.According to the applicable region of each distribution function, the flow sub-division is determined. It is found that the boundary heights do not coincide with the characteristic heights, but are approximately equal to the upper and lower boundaries of the mixing layer.The comparison with other studies illustrates that the proposed dimensionless method, the piecewise functions and the flow sub-division are effective for describing the velocity with good applicability.