Fully three-dimensional Reynolds-averaged Navier-Stokes modeling for solving free surface flows around coastal drainage gates

In this study we carry out numerical simulations of free surface flow through the drainage gates of the Saemangeum tidal barrier that is located in the west coast of South Korea and is also known as the world largest man-made tidal barrier. Instead of using depth-averaged numerical models, which have been widely used in hydraulic and coastal engineering, we employ the fully three-dimensional free surface flow model of Kang and Sotiropoulos (2012b) to simulate the flow around the gates. The numerical model is based on the two-phase level set method solving the air and water simultaneously and the curvilinear immersed boundary method that is able to handle arbitrarily complex geometries. In the simulations turbulent flows are also resolved by the shear stress transport k−ω model. The numerical model is applied to simulate fifteen different flow conditions with various gate opening scenarios, and for selected test cases laboratory experiments are also carried out. The computed flowfields at various flow conditions are compared with the laboratory measurements and the field observations and the comparisons showed satisfactory agreements both quantitatively and qualitatively. Using numerical simulation results, we elucidate the structures of turbulent flows associated with a high-speed jet-flow like structure and a hydraulic jump at the far downstream of the gates. The results presented in this paper demonstrate the predictive capabilities of the numerical model and its potential as a powerful engineering tool for estimating the discharge-water level relationship and the three-dimensional flowfield of real-life drainage gates.