Abstract: The differences in hydraulic characteristics between two energy dissipation approaches, combination of diversion pier and suspended grid and single suspended grid, were investigated by tracking the nonlinear free surface using the VOF method based on the Navier-Stokes equation. The large-scale turbulence and intensive air entrainment in the hydraulic jump were simulated. On this basis, the detained flow structure and wall pressure in the stilling pool were obtained for analyzing the turbulence and pressure distribution. Results illustrated that the joint energy dissipator significantly increased the turbulent intensity and fluctuating scale of water body in the paraboloid of stilling basin. The turbulence intensity, which decayed remarkably along the flow direction, was highly improved compared with the control scheme (single suspended grid) for relative depth h^* in the range from 0.4 to 0.8. Hydrodynamic pressure on the base slab of stilling pool fluctuated notably, and the average pressure reduced slightly compared with that in the control scheme. The peak of pressure fluctuation is located nearby 0.3＜x_p＜0.4(x_p is the relative location), and the dynamic pressure coefficient is 2.0~2.4 times of the maximum value on the base slab of the pool.

Key words: hydraulic jump, suspended grid, joint energy dissipator, numerical simulation, turbulent intensity, pressure coefficient