刚性非浸没式植被对弯道水流特性的影响  

Effect of rigid and emergent vegetation on flow characteristics in a curved channel

作　　者：方佐赐 何昊哲 林颖典 

机构地区：[1]浙江大学海洋学院,浙江舟山316021

出　　处：《水动力学研究与进展（A辑）》2017年第5期645-654,共10页Chinese Journal of Hydrodynamics

基　　金：国家自然科学基金(11672267)~~

摘　　要：该文采用180°U形矩形截面弯道玻璃水槽模拟天然弯道河流,运用声学多普勒流速仪(acoustic doppler velocimeter,ADV)研究刚性非浸没式植被(密度4.47%)对弯道水流纵向流速分布,横向环流及湍流动能(turbulence kinetic energy,TKE)的影响。实验结果表明,当水槽流量较小时,植被对水流的阻碍作用较小,由流速降低而导致的水深增加现象不明显,当水槽流量增大时候,植被对水位的抬升现象明显;水流受植被"阻滞"作用,弯道处纵向流速沿水深分布不再服从"对数型"分布规律,且原本水流受弯道作用后呈现的"上减下增"效果也消失;植被加快了最大流速区向凸岸转移,到达弯道出口时,最大流速区逐渐转移至断面中部区域;在植被的影响下,各断面弯道环流消失;植被会加剧水流紊动效应,导致湍动加剧,TKE增大。上述实验结论将增进研究者对植被对弯道水流特性影响的理解,同时也为泥沙疏浚,河道生态系统恢复提供指导。In this paper, a 180 degrees U-turn rectangular channel was used to simulate the flow patterns in natural channel bends. The distribution of flow velocity, lateral circulation and the turbulence kinetic energy（TKE） within 4.47% rigid and emergent model vegetation were studied using the Acoustic Doppler Velocimeter（ADV）. The experimental results show that when the flow rate is small, the increase of the water depth within 4.47% model vegetation is not obvious. On the other hand, as the flow rate becomes larger, the 4.47% vegetation cause the significant increases in water depth along the channel curve. Due to the vegetation, the velocity profiles along the mean flow direction is no longer subject to logarithmic distribution as the case without vegetation and the lateral circulation patterns disappear as the water flows around the channel bend. In comparison to the case without vegetation, the maximum flow velocity region within vegetation appears earlier in the convex bank but can only move to the central region at the bend exit. The 4.47% vegetation also enhances the TKE for the bend flow. These findings will improve the understanding of the vegetation role on the flow characteristics of the curved channel and provide guidance for sediment dredging and river ecosystem restoration.

关 键 词：弯道河流 声学多普勒流速仪(ADV) 刚性非浸没式植被 横向环流 湍流动能(TKE) 

分 类 号：TV148[水利工程—水力学及河流动力学]