弯道植被水流中Monami现象及湍流特性试验研究  

Experimental Study on Monami Phenomenon and Turbulence Characteristics in Vegetated Flow of Curved Channel

作　　者：黄天炜 林颖典 Huang Tianwei;Lin Yingtien(Ocean College,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]浙江大学海洋学院,杭州310058

出　　处：《水动力学研究与进展（A辑）》2023年第5期755-765,共11页Chinese Journal of Hydrodynamics

摘　　要：自然河流中生长的水生植物是生态系统的重要组成部分,植物的形态变化会影响水流的流动特性及污染物的输运。该文利用U型折叠弯道水槽进行试验,设置半侧分布的柔性植被,分析在弯道水流下不同流量及柔性植被配置对Monami现象的影响。试验结果表明:不同流量下的柔性植被形态存在差异,进而影响流速分布,当流量较大时,弯道中会出现Monami现象。在不同流量下,植被形态在弯道入口处呈现Monami现象、倾斜倒伏或直立;而在弯道后半程呈现Monami现象或无组织性轻微摆动。通过功率谱频率分析的高相关性证明Monami现象由K-H涡的不稳定性产生,且在弯道中,Monami频率减小。植被叶片的摆动使得湍流应力更深入植被冠层,而Monami现象的出现降低了植被冠层边界动量传输效率。此外,弯道会扩大植被冠层内扫掠主导区域的影响范围,改变无植被区的湍流活动类型。Aquatic plants are a critical component of river ecosystems, and changes in their morphology can impact the flow patterns and transport of pollutants. In this study, experiments are conducted in a U-shaped flume with flexible vegetation distributed on one side to investigate the impact of different flow rates and vegetation configurations on the Monami phenomenon. The experimental results demonstrate that there are differences in the morphology of flexible vegetation under different flow rates, which in turn affects the velocity distribution. When flow rate is large, the Monami phenomenon occurs in the curve. The vegetation morphology exhibits Monami, proning or erecting at the entrance of the bend, while Monami or gently swaying in the latter half of the bend. Frequency analysis of power spectrum density indicates that the Monami phenomenon is caused by instability of K-H vortices, and the Monami frequency decreases along channel curves. Furthermore, the oscillation of vegetation leaves increases turbulent stress within the vegetation canopy, and momentum transfer efficiency at the canopy boundary is decreased with Monami. Besides, channel curves expand the influence range of sweeping-dominant areas within the vegetation canopy and change the type of turbulent activity in non-vegetation areas.

关 键 词：柔性植被 弯道水流 Monami现象 流速分布 K-H不稳定性 

分 类 号：TV139.2[水利工程—水力学及河流动力学]