The breakup of oil spills in the marine environment

The behavior of oil spilled in the ocean depends on its physical properties, chemical composition, and the environmental conditions, i.e., water and air temperatures, wind speed, and turbulent energy produced by wind, currents, and waves. Oil spill models, commonly used to predict this behavior, can not resolve the fine structures at reasonable computational cost. Hence, the small scale processes are included in these models through empirical sub-models. Many difficulties are encountered in modeling the emulsification process. Chief amongst them is the prediction of the onset and extent of oil spill emulsification. The aim of this paper is to address the modeling of slick breakup and onset of emulsification. The existing theories on oil slick disintegration under stormy conditions are examined and a novel empirical model which is suitable to use in oilspill models is presented. We begin by summarizing the standard theories for droplet breakup in turbulent flows and their application to oilspill modeling. The important parameters controlling the breakup and mixing processes are identified using previous oilspill incidents and the aid of marine boundary layer (MBL) measurements. An empirical model for the slick breakup and onset of emulsion formation is then presented. In this model the surface active constituents and energy available from wind and waves are used as the controlling parameters. The model predicts dynamical breakup and can be easily implemented in working oilspill models to produce localized emulsification effects.