Large eddy simulation of wind turbulence over non-breaking and breaking waves

Wind-wave interaction affects the wind-wave fields and the combined loading on structures. This study aims to characterize turbulent airflow over non-breaking and breaking waves using a high-fidelity two-phase model in OpenFOAM. The volume of fluid method is utilized to model the complex air–water interface. Wind turbulence is considered via prescribing it at the inlet boundary. The model is validated against experimental data, and a numerical case study is conducted to simulate extreme wind and wave-plunging conditions. Results reveal that non-breaking waves induce wind turbulence and affect averaged wind velocity. For wave steepness exceeding 0.35, extreme wind forces amplify the turbulence by over 100% at wave crests. The amplified turbulence region extends to about 0.6λ in height. When waves plunge, an overturning jet propels the wind forward, generates a counterclockwise vortex, and enhances wind turbulence. Averaged wind speeds increase by over 20% above wave crests, with the enhanced region extending to a height of around 0.2λ for old waves. Maximum turbulence kinetic energy transiently increases by around 0.1Cp2 and maximum kinematic energy of wave-coherent velocity increases and subsequently decreases during wave plunging. •An LES-based two-phase model is developed to simulate coupled turbulent wind-wave flows.•Simulated wind-wave flow characteristics agree well with the experimental data.•Over non-breaking waves, the wave generated wind turbulence depends on wave ages.•Over plunging waves, a counterclockwise vortex forms, enhancing wind turbulence.•Wave breaking has a significant impact on the pattern of phase-averaged wind speed.