Air entrainment and underwater noise of breaking waves

Breaking waves and bubbles play an important role in many upper-ocean physical processes, including enhancement of air-sea gas and momentum transfer and wave noise generation. In this study, we perform numerical simulations for wave breaking and bubbly flows using a new simulation method that computes resolved bubbles and subgrid-scale bubbles dynamically. Bubbles larger than the grid size are directly captured by a coupled level-set and volume-of-fluid method. Subgrid-scale bubbles are modeled using a four-way coupled polydispersed two-fluid model. We calculate the underwater noise based on a sound generation model, bubble identification procedure for resolved bubbles, and bubble entrainment modeling for subgrid scale bubbles. By analyzing the data from our simulation results, we investigate the air entrainment and sound generation in breaking waves. The results show that our numerical method can capture the wave breaking and air entrainment processes accurately. A comparison of calculated and observed wave noise will be presented and discussed.