Modeling Oil Droplet Formation and Evolution under Breaking Waves

Abstract

A research program was initiated to develop numerical models to describe oil droplet formation and behavior following oil spills at sea. Specifically, suitable models have been examined to quantify the energy requirement for the formation of oil droplets and their subsequent mixing and resurfacing. Wave energy dissipation rate is a critical parameter governing the evolution of spilled oil including its droplet size distribution, breakup, coalesce, and dispersion. Methods of computing the energy dissipation rate were researched, and one was selected for a detailed study of oil droplet kinetics. Additionally, a population model was developed to account for the evolution of oil droplets under typical wave energy levels. Preliminary validation of the proposed models, using a full-scale computer-controlled wave tank facility at the Centre for Offshore Oil and Gas Environmental Research (COOGER), showed good agreement between experimental data and predictions for mean oil droplet diameter under breaking wave conditions for time intervals of 1, 10, 60, and 300 min after the spill. A similar correlation was observed for oil concentration in the aqueous phase. Comparisons were also made to evaluate the influence of energy on oil droplet behavior in the presence of chemical dispersants. The study results will be used to formulate a standard procedure for developing new oil spill countermeasures.