Wouter Mostert

Direct numerical modelling of breaking waves, bubbles, and droplets

Breaking ocean waves constitute one of nature’s most familiar phenomena, but they remain poorly understood in many ways. They strongly influence the transport of mass, momentum and energy - and other aspects of air-sea interaction - between the ocean and atmosphere: for example, via the entrainment of air in the form of bubbles, they supply the mechanism for a large proportion of the ocean’s uptake of anthropogenically emitted CO2. But breaking wave systems are challenging to investigate because, among other things, their physics span so many scales, ranging from the submicron (even nanometric!) to the hundreds of kilometres, and only recently has it become feasible to use numerical methods to inspect even some of these mechanisms in close detail. In this talk I will discuss the role of direct numerical simulation in the space of wave modelling problems, and proceed to present high-resolution simulations of breaking waves, and of the bubbles and droplets they may produce. Scaling and physical argumentation can be used to interpret these results, which may be applied in the form of parametrisations to larger-scale models. To conclude, I will discuss some open questions and challenges still to be tackled in this fascinating topic.