Abstract
A stilling basin with sudden enlargement and bottom drop leads to complicated hydraulic characteristics, especially a fluctuating pressure distribution beneath 3D spatial hydraulic jumps. This paper used the large eddy simulation (LES) model and the TruVOF method based on FLOW-3D software to simulate the time-average pressure, root mean square (RMS) of fluctuating pressure, maximum and minimum pressure of a stilling basin slab. Compared with physical model results, the simulation results show that the LES model can simulate the fluctuating water flow pressure in a stilling basin reliably. The maximum value of RMS of fluctuating pressure appears in the vicinity of the front of the stilling basin and the extension line of the side wall. Based on the generating mechanism of fluctuating pressure and the Poisson Equation derived from the Navier–Stokes Equation, this paper provides a research method of combining quantitative analysis of influencing factors (fluctuating velocity, velocity gradient, and fluctuating vorticity) and qualitative analysis of the characteristics of fluctuating pressure. The distribution of fluctuating pressure in the swirling zone of the stilling basin and the wall-attached jet zone is mainly affected by the vortex and fluctuating flow velocity, respectively, and the distribution in the impinging zone is caused by fluctuating velocity, velocity gradient and fluctuating vorticity.
Highlights
Energy dissipation by hydraulic jump is a traditional method that is used to dissipate excess energy, where the stilling basin is an important part of the energy-dissipating structures
Since the stilling basin is an axisymmetric structure, its center line is recorded as y = 0 cm, and the endpoint coordinate y = 80 cm at the position offset from the center line to the left by 80 cm
On horizontal distribution of fluctuating pressure coefficient. Both sudden lateral enlargement and bottom drop will result in the difference distributions of spatial hydraulic jumps compared with those of equivalent classical hydraulic
Summary
Energy dissipation by hydraulic jump is a traditional method that is used to dissipate excess energy, where the stilling basin is an important part of the energy-dissipating structures. Fluctuating pressure beneath hydraulic jumps can cause extremely serious damage, and the fluctuating lifting force is an important factor in the failure of the stilling basin slab. Seyed Nasrollah et al [3] advanced and predicted fluctuating pressure and extreme pressure beneath hydraulic jumps with a statistical method. To solve these problems, stilling basins with bottom drop were applied in many actual energy dissipation projects, such as Xiangjiaba Dam, Jinanqiao Dam, and so on. Luo et al [6] studied the distribution characteristics of fluctuation pressure and lifting load in a stilling basin with step-down for floor slab
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