浸没式人工刚性植被群分布对弯道水流特性的影响  

Effect of submerged and rigid artificial vegetation distributions on curved channel flow

作　　者：杨彧 林颖典 YANG Yu;LIN Ying-tien(Ocean College,Zhejiang University,Hangzhou 310058,Zhejiang,China)

机构地区：[1]浙江大学海洋学院,浙江杭州310058

出　　处：《水动力学研究与进展（A辑）》2021年第1期85-94,共10页Chinese Journal of Hydrodynamics

基　　金：国家重点研发计划(2016YFC0402406);舟山市科技计划项目浙江大学海洋学院专项(2018C81034);中央高校基本科研业务费专项资金资助(2020QNA4038)。

摘　　要：自然弯曲河流中,浸没式植被的存在及分布会改变其水动力特性,进而影响弯曲河道泥沙输移及底床变化。该研究采用180°U形折叠往返式水槽模拟天然弯道河流,木棒模拟刚性植被,运用声学多普勒流速仪(AcousticDoppler Velocimeter, ADV)进行测量,分析不同人工浸没式植被的分布对弯道纵向流速分布、湍流动能(Turbulence Kinetic Energy,TKE),环流强度以及湍流谱分布等的影响。实验结果表明,在植被顶部出现流速的最大值。浸没式植被和弯道都会加剧水流紊动效应,湍流动能最大值出现在植被顶部稍往下区域,且进入弯道以后最大值的位置明显下移。不同的植被群分布使得湍流动能的分布情况不同,凸岸植被减小了无植被区(凹岸)的湍流动能,而凹岸植被增大了无植被区(凸岸)的湍流动能。浸没式植被的存在使得植被区和无植被区的弯道环流方向相反。此外,通过湍流谱分析,植被和弯道都会增强湍流强度,且小湍涡增多;植被与无植被的交界区(横向和垂向)都会增加水体之间的掺混,使得湍流在交界区域明显变强。In natural river bend, the presence and distribution of submerged vegetation would change the hydrodynamic performance of the river flow and subsequently affect the sediment transport and the bed deformation. In this study, a 180°U-shaped curved open channel is used to simulate the natural river bend, and wood sticks are applied to simulate the rigid vegetation. The variations of longitudinal velocity distribution, turbulence kinetic energy(TKE), bend circulation and power spectral analysis are obtained using measured data from the Acoustic Doppler Velocimeter(ADV). The results show that the longitudinal velocity is the largest at the top of vegetation. Various vegetation distribution and channel bend both strengthen the turbulence,especially around the top of the submerged vegetation. TKE is the largest below the top of submerged and rigid vegetation and decays downward into the vegetation. There is also secondary flow within submerged vegetation, but the directions of secondary flow in vegetation area and non-vegetation area are opposite. Through power spectral analysis, it is indicated that the submerged and rigid vegetation and channel bends will increase the intensity of turbulence and the amount of small scale turbulent vortex;the mixing of water bodies at the interface between vegetation and non-vegetation area(lateral and vertical direction) is stronger, also the turbulence is intensified evidently at the interface area.

关 键 词：刚性浸没式植被 纵向流速分布 湍流动能 弯道环流 湍流谱 

分 类 号：TV133[水利工程—水力学及河流动力学]