The breaking of ocean waves plays a crucial role in the fluid mechanics of mass, momentum, and energy transfer between the Earth's ocean and atmosphere, but nevertheless remains incompletely understood. Breaking waves ingest air into the water in the form of bubbles and eject spray into the air, some of which persists in the atmosphere as sea spray aerosols; they also dissipate wave energy and modulate the dynamics of the upper ocean. In this talk, Mostert will present results from high-resolution direct numerical simulations of breaking waves in shallow and deep water, obtaining detailed information on energy dissipation in the liquid phase along with bubble and droplet populations directly resolved by the numerical method. This enables an examination of the transition from two-dimensional laminar flow in the incipient breaker to three-dimensional turbulent flow in the active breaking process; the concomitant production of bubble size distributions in the liquid phase spanning several orders of magnitude, and resolved across different regimes of bubble formation and breakup; and the spray generated by the breaker splash-up. Such comprehensive datasets are a useful tool for understanding the physics of basic air-sea exchange processes at the small scale, which may in turn lead to the development of more physically informed scaling models in regional wave models.
Available for public on Youtube: <https://www.youtube.com/watch?v=xaZmWntAit0>
Box Recordings for Caltech: <https://caltech.box.com/s/grvxyi8ljwrrpwjq2bkkzy7vbf40235h>