部分植被化矩形河槽紊流时均流速分布分析解

Analytical Solutions for the Transverse Distributions of Stream-Wise Velocity in Turbulent Flow in Rectangular Channel With Partially Vegetations

研究了部分植被化矩形河槽紊流的水深平均流速分布.植被被视为不可移动的刚性多孔介质,植被对水流的阻力以多孔介质理论加以考虑,并综合考虑部分植被存在时矩形河槽紊动水流二次流的作用,建立了紊流动量方程.针对恒定均匀流的特点,对动量方程进行了简化,沿水深方向积分并引入参考量,形成无量纲形式的基于多孔介质理论紊动水流控制方程,进而对其求解给出了水深平均纵向时均流速分布的分析解.研究表明,在不同水流条件下的二次流强度系数具有相同的数量级.为验证分析解的正确性,在实验室采用MicoADV测量了部分植被化矩形河槽水流的流速分布.数值解与实验资料和日本学者的相关实验资料的对比表明,该方法可以准确预测部分植被化矩形河槽紊流水流的水深平均流速分布.

The lateral distribution of longitudinal velocity in steady uniform turbulent flow in partially vegetated rectangular channel was studied.Plants were assumed as immovable medium.The resistance caused by vegetation was expressed by the theory of poroelasticity.With the consideration of the influence of secondary flow,the momentum equation could be settled.The momentum equation was simplified due to the characters of steady uniform flow.The momentum equation was nondimensionalized to obtain a smooth solution for the lateral distribution of longitudinal velocity.The research shows the secondary current intensity coefficient is in the same order of magnitude under different flow conditions.To verify the model,the acoustic Doppler velocimeter（Micro ADV） is used to measure the velocity field in a rectangular open channel partially with emergent artificial rigid vegetation.Comparisons between the measured data,from both the experiment and the Japanese researchers＇ paper,and the computed results show that the method did well in predicting the transverse distributions of stream-wise velocity in turbulent flow in rectangular channel with partially vegetations.