Scale effects for air entrainment in quasi-steady breaking waves

Quasi-steady breaking waves are prominent and highly observable features in civil, environmental, ocean and naval engineering applications with direct impact on turbulent dissipation and air-sea interaction. We use high-resolution 3D direct numerical simulation and implicit large eddy simulation of quasi-steady breaking waves to study the air entrainment characteristics as a function of resolvable features within the wave. The numerical method utilizes conservative Volume of Fluid (cVOF) to capture the interface on a Cartesian grid. A submerged lifting body generates the quasi-steady breaking wave. For low Reynolds number waves, we observe periodic wave breaking and entrainment and show that the bubble-size distribution (above the Hinze scale) for each entrainment period achieves an expected slope of r^-β, β=10/3. For high Reynolds number waves, we observe widespread wave breaking and entrainment. The slope of the bubble-size distribution β>10/3 reflects entrainment with continued breakup of the entrained cavities by turbulence. Our particular interest lies in developing parameterizations and models that relate the entrainment due to quasi-steady wave breaking to underlying flow characteristics.