Simulation and Analysis of Breaking Wave in Deep Water

Breaking wave has often been observed in ocean, the violent mixture of gas and water creates numerous bubbles and droplets in different scales. The generation of two-phase turbulence during breaking process accounts for a large portion of wave energy dissipation and momentum exchange. However, the multi-scale turbulence of wave breaking has rarely been studied by experimental measurement and numerical simulations. In this study, the two-phase Navier-Stokes equations are solved based on Cartesian grid solver. To reproduce the free surface and multi-scale flow structures accurately, a block-structured adaptive mesh refinement strategy is adopted. For better representation of the violent free surface, a mass-conservative interface capturing method CLSVOF (coupled level-set and volume of fluid) is implemented. Since a deep water assumption is hold, the viscosity of water and air will not be considered in current stage. For capturing the detailed flow characteristics of the plunging, a novel vortex-structure visualization approach, the Liutex (previously named Rortex) method is adopted. A series of deep water breaking-wave cases considering various wave steepness (corresponding to weak plunging, plunging, strong plunging etc.) are under numerical investigation. The air entrainment, violent two-phase mixture during the breaking process are well reproduced. Vortex structure identified by Liutex is given for comparison.