沙波与植物复合床面明渠紊流结构及泥沙输移研究

Researches on the turbulence structure and sediment transport over the compound bed forms with dunes and vegetation in open channel flow, which concern the complicated interaction among flow, sediment and vegetation, are important basis of researches on water environment governance and water ecosystem restoration. The proposal plans to utilize the natural sand to form bed forms as the relaxed boundary and the plastic slice to simulate the vegetation as the flexible boundary, respectively. With the Acoustic Doppler Velocimeter, Particle Image Velocimeter and Image Processing Technique, the turbulent flow characteristics, sediment concentration and sediment transport will be measured and studied. Based on the experimental data, the critical conditions of sediment saltation and suspension over compound bed forms will be proposed, the interaction mechanism among flow, sediment and vegetation will be revealed, and a new formula of sediment transport rate including dunes and vegetation factors will be established. This research will enrich the theory of open channel turbulence and sediment transport mechanism, promote the research of flow-sediment transport under relaxed and flexible boundaries, and also can provide scientific guidance to fluvial processes analysis and river environmental and ecological treatment.

沙波与植物共存条件下的明渠紊流结构和泥沙运动研究，涉及到水、沙、植物三者之间的相互作用，是水环境治理与水生态系统修复研究的重要基础。本项目拟采用天然沙塑造沙波作为明渠床面"松散边界"，采用具有一定刚度的塑料片来模拟天然植物形成的"柔性边界"，利用超声波流速仪、粒子图像测速系统以及图像处理技术等，对沙波与植物复合床面条件下的明渠紊流特性和泥沙输移规律进行详尽细致的研究，定量描述三维可动沙波和植物共存条件下明渠水流的时均流速、紊动强度分布规律及拟序结构特征，确定泥沙颗粒跃移、扬动的判别指标和临界条件，揭示水、沙、植物相互作用机制，建立综合考虑沙波和植物因素的输沙率公式。本项目的研究成果将丰富明渠紊流和泥沙运动力学理论，完善"松散和柔性边界水沙动力学"研究，同时为天然河流演变分析以及河流环境生态治理提供科学依据。

沙波与植物共存条件下的明渠紊流结构和泥沙运动研究，涉及到水、沙、植物三者之间的相互作用，是水环境治理与水生态系统修复研究的重要基础。本项目采用水槽试验和理论分析相结合的方法，利用声学多普勒流速仪、粒子图像测速系统以及图像处理技术等，对沙波与植物复合床面条件下的明渠紊流特性和泥沙输移规律进行了详细的研究，获得了沙波床面、植物床面和沙波与植物共存条件下明渠水流的时均流速、紊动强度分布规律及拟序结构特征，通过象限分析法得到了不同床面条件的平均喷射和清扫周期以及各象限事件占总量的比例，并对沙波床面喷射和清扫的强度分布进行了统计分析，建立了综合考虑沙波和植物因素的明渠推移质输沙率公式。本项目的研究成果丰富了明渠紊流和泥沙运动力学理论，完善了"松散和柔性边界水沙动力学"研究，同时为天然河流演变分析以及河流环境生态治理提供科学依据。