| 基于水下摄影的床面泥沙运动特性试验研究 |
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| 引用本文： | 刘明潇,MicheleGuala,孙东坡.基于水下摄影的床面泥沙运动特性试验研究[J].水科学进展,2021,32(3):449-457. |
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| 作者姓名： | 刘明潇 MicheleGuala 孙东坡 |
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| 作者单位： | 1.华北水利水电大学水利学院, 河南郑州 450046 |
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| 基金项目： | 国家自然科学基金资助项目51909093国家自然科学基金资助项目52079032 |
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| 摘 要： | 为提高推移质试验的观测精度与效率，基于水下摄影和粒子跟踪（UP/PTV）技术，实现明槽流床面泥沙运动状态的精细试验观测。通过剔除床面颗粒震颤干扰、设置颗粒临界运动阈值和多重滤波筛选程序，提高采集样本数据的有效性。利用多组低强度推移质试验，提取床面颗粒运动轨迹、速度、单步时长等数据，并进行粒子运动的Lagrange过程分析和概率密度分布（PDF）研究。研究表明:粒间碰撞和近底紊流扫荡的影响使粒子速度在单步步长内呈现先急剧增加再缓慢衰减的变化特征；速度PDF曲线显示细尾Gamma函数特性，同时受粒子震颤效应影响，加速度PDF曲线则具有拉普拉斯分布特征；粒子速度与摩阻流速之间关系密切，保持3.4~3.5的比值；粒子单步时长与步长的联合分布呈幂函数变化规律，拟合曲线指数一般为1.25~1.3。幂律指数大小受推移质输沙强度与床面粒子异质性的影响。
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| 关 键 词： | 床面泥沙 粒子跟踪技术 水下摄影 粒子状态 活跃等待 细尾分布 |
| 收稿时间： | 2020-03-03 |
Experimental study on the property of bed load motion based on the underwater photography technology |
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| Institution: | 1.School of Water Conservancy, North China University of Water Resources and Electric Power, Zhengzhou 450046, China2.St. Antony Fall Laboratory, University of Minnesota, Minneapolis 55414, USA |
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| Abstract: | In order to improve the observation accuracy and efficiency of bed load experiments, the fine experimental observations of the movement and the state transition of bed sands in open channel flow were accomplished by means of underwater photography and particle tracking (UP/PTV). The reliability of the sampling data was improved by removing the interference caused by bed sands wagging, and setting the critical threshold of particle motion state as well as adapting multiple filter screening programs. By conducting series of bed load experiments under low transport intensity conditions, data including motion trajectory, velocity and step duration of bed particle was obtained, which was analyzed using a Lagrange process and the Probability Density Function (PDF) of the particle motion elements. Experimental results indicated that, the particle velocity shows a trend that increases rapidly at first and then decays slowly during the process of one single step, which is caused by inter particle collision and sweep events of near-bed turbulence. The PDF curve of particle velocity presents the Gamma function distribution with a thin tail, while the PDF curve of particle acceleration shows the Laplace distribution characteristics, influenced by the particle wagging effect. The particle velocity is closely associated with the friction velocity u*, maintaining a ratio of 3.4 to 3.5. The joint distribution of the single step duration Ts and the single step length Ls of the particles presents an exponential function, and the exponent of the fitting curves ranges between 1.25 and 1.30. The exponent is associated with the transport intensity of bed load and the heterogeneity of the bed surface particles. |
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