Research on the Influence of Trench Length on the Water Level Fluctuation of Typical Aqueducts in the Middle Route of South to North Water Transfer Project.

During the large-flow water transmission of the middle line of the South-to-North Water Diversion Project, some aqueducts experienced varying degrees of water level fluctuations, which had a certain impact on safety scheduling, especially the shorter the aqueduct body, the more obvious the phenomenon. In this paper, the RNG k-ε model and Tru-VOF method are used to establish several sets of full three-dimensional numerical models with different tank lengths for typical aqueducts, and explore the influence of tank length parameters on water level fluctuations. The results show that the Carmen vortex street formed at the exit of the tail pier downstream of the aqueduct is the source of fluctuations, and the vortex causes local water blockage, which in turn generates fluctuations to be transmitted upstream. With the increase in the length of the tank, the fluctuation transfer energy is gradually dissipated, the maximum flow velocity and the amplitude of water level fluctuation continue to decrease, and when the length exceeds 800 m, the water level fluctuation energy is basically dissipated. The results can provide a reference for the smooth scheduling and safe operation of the project. [ABSTRACT FROM AUTHOR]