Abstract: The production of sea spray by the ocean accounts is a significant component of air-sea mass exchange, and is central to many engineering problems such as marine icing. But it encompasses a baffling array of spray length and time scales, physical mechanisms of production and breakup, and source phenomena. Teasing apart and understanding individual physical mechanisms can for example help in the formation of ground-up models for sea spray generation functions (SSGFs), which describe the rate of production of spray droplets of a given size, per unit area of sea surface, as a function of wind speeds and (arguably) sea states. In this talk I will present numerical studies of droplet production by aerobreakup (i.e. as spume), and by splashing: the two mechanisms hypothesised to produce the largest species of sea spray. Both mechanisms have long been intractable for numerical investigation, although recent developments in numerical techniques and availability of computational resources have enabled some big new steps to be taken. First, although a final conclusion on the smallest droplets from aerobreakup – particularly bag-breakup, the gentlest kind of aerobreakup – is still elusive, it is now within reach so that a full SSGF for wind-driven spume production lies in the near future. Second, for splashing, it is possible to produce statistics that are not only well-resolved numerically, but can also be addressed with some simple theoretical modelling. I will conclude with a discussion on ground-up SSGFs and possible routes forward in quantifying the fascinating phenomena of sea spray.
Short Bio: Wouter Mostert is an Associate Professor of Engineering Science at the University of Oxford. He has previously held appointments at the Missouri University of Science and Technology, Caltech, and Princeton University, having obtained his Bachelor’s and PhD degrees at the University of Queensland. Wouter’s research interests lie in computational and theoretical analysis of fluid mechanics, relevant across a large range of fluid problems, such as evolution and fragmentation of bubbles and droplets, and breaking ocean waves, although he has also investigated nonlinear evolution of shock waves and hydrodynamic instabilities of magnetised plasmas.