Oil droplet size model for ocean surface oil spills: impact of breaking wave height and oil properties

Abstract

One of the key parameters that has been identified to affect the accuracy of the oil spreading calculations from ocean oil spill models is the oil Droplet Size Distribution (DSD). The oil droplet dynamics in the water column plays a critical role in oil spreading and subsequent oil weathering processes. Thus, accounting for the droplet dynamics under wave conditions is a critical issue in ocean oil spreading models. In this regard, droplet dynamic models have shown promising results. In the present study, a phenomenological droplet dynamic model is employed to analyse the impact of wave parameters and oil properties on the developed oil DSD. The model results confirm the capability of the phenomenological models to calculate the evolution of oil DSD under breaking wave conditions, which is an advantage over equilibrium models. The model was used to analyse how the developed droplet sizes vary with different breaking wave heights, oil types, and differently weathered oils. The model results show that increasing breaking wave height results in a shift of oil DSD towards smaller droplet sizes, however the impact of oil viscosity is comparatively less for the selected range of oils.