Experimental study on flow structure in riffle-pool channels

2018 1st International Conference on Environment Prevention and Pollution Control Technology

生态环境科学

Li, Like^1 ; Fan, Niannian^1 ; Liu, Xingnian^1

State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, China^1

关键词: Acoustic Doppler velocimeter;    Channel geometry;    Hydraulic characteristic;    Irregular cross-sections;    Laser range finders;    Shallow water depths;    Shearing action;    Time-averaged velocity;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/199/5/052055/pdf
DOI  :  10.1088/1755-1315/199/5/052055

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

Because of the riverbed evolution and geological tectonics, the river geometry has changed obviously, forming a wide and narrow alternated channel. The area with shallow water depth is easy to form riffles. The area with narrow deep water often forms deep pools. Flow rate will increase or decrease. The hydraulic characteristics of riffle-pool with clear water scouring under steady state were studied by using three-dimensional overlooking acoustic Doppler velocimeter (ADV: Nortek-vectrino II), a camera, a underwater high-speed camera and a laser rangefinder. The results showed that with the change of channel geometry, the water level of cross-section would change accordingly; logarithm law could well describe the time-averaged velocity distribution near the wall. However, the bed morphology affected the flow structure near the bed to a certain extent; because of the irregular cross-section and the influence of the bed topography, the cross-section gradually changed. The Reynolds stress varied significantly in the area where the cross-section decreased gradually, indicating that the water body had strong shearing action. In the enlarged area, the Reynolds stress distributed uniformly.