带滩槽地形的连续弯道中纵向流速横向分布解析  

THE LATERAL DISTRIBUTION OF DEPTH-AVERAGED VELOCITY IN CONSECUTIVE BENDS WITH POOL-POINT BAR

作　　者：刘玉娇 余明辉[1] 田浩永 Liu Yujiao;Yu Minghui;Tian Haoyong(State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室,武汉430072

出　　处：《力学学报》2021年第2期580-588,I0005,共10页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(11972265);国家重点研发计划(2016YFC0402604)资助项目。

摘　　要：本文基于沿水深积分的动量方程,假定二次流项和弯道附加应力项沿横断面呈线性分布,提出了预测弯道垂线平均纵向流速的解析计算方法,进一步提出了河槽区和河滩区垂线平均纵向流速沿断面分布的求解模式,并将其应用于带滩槽地形的反向连续弯道水槽中.根据实测数据率定计算参数,该模式可计算不同出口水深条件下断面垂线平均纵向流速分布,计算结果与实测数据吻合良好.分析了线性分布假设中参数随水深变化的取值规律和沿横断面分布特点,并对参数进行了敏感性分析,分析表明线性假设中一次项系数分区位置对流速峰值的大小和位置影响较大,常数项根据地形横比降变化进行分区取值,流速计算值对常数项在水平段和斜坡段分区位置较为敏感,并根据参数的敏感度提出了参数沿水槽的均值作为参考值.讨论了动量方程中二次流项和弯道附加应力项沿弯道的横向分布规律,进一步认识线性假设的适用范围,结果表明线性假设在本文试验水槽中适用于弯道沿程.研究成果有助于认识带滩槽地形的连续弯道纵向流速分布特征及其形成机制.This paper proposes an analytical approach to modeling the lateral distribution of depth-averaged streamwise velocity for flow in consecutive bends with pool-point bar based on the depth-integrated Navier–Stokes equations.The additional secondary flow and yet fully developed flow are assumed to be a linear function of the lateral distance.Then,the model for calculating the average vertical velocity distribution along the cross section of the pool region and the point bar regions is presented,and it is applied to consecutive bends with pool-point bar.By calibrating the calculated parameters from the measured data,the model can calculate the average longitudinal velocity distribution of vertical cross-section under different outlet water depth.The modeled results agree well with experimental data.The value rules of the parameters have analyzed for different water depth and along the cross-sections.Sensitivity analysis is performed on the parameters which showed that the region division of the coefficient of the first degree term in the linear hypothesis has great influence on the size and position of the peak flow velocity.The region division of the constant term value is according to the traverse gradient.The region edge between the flat bed and the sloping bed of the constant term has a significant influence on the results.According to the sensitivity of parameters,the mean value of parameters along the flume is presented as a reference value.The transverse distribution of the secondary flow term and the additional stress term in the depth-integrated Navier–Stokes equations along the experimental channel is discussed to further understand the applicability of the linear hypothesis.The results show that the linear hypothesis is suitable for the curve path in the flume.The research results are helpful to understand the longitudinal velocity distribution characteristics and the formation mechanism of the consecutive bends with pool-point bar.

关 键 词：连续弯道 纵向流速 滩槽 明渠水流 解析解 

分 类 号：TV131.1[水利工程—水力学及河流动力学]