Large-Eddy Simulations of Oil Droplet Aerosol Transport in the Marine Atmospheric Boundary Layer

In this study, a hybrid large-eddy simulation (LES) model is developed and applied to simulate the transport of oil droplet aerosols in wind over progressive water waves. The LES model employs a hybrid spectral and finite difference method for simulating the wind turbulence and a bounded finite-volume method for modeling the oil aerosol transport. Using a wave-following coordinate system and computational grid, the LES model captures the turbulent flow and oil aerosol fields in the region adjacent to the unsteady wave surface. A flat-surface case with prescribed roughness (representing a pure wind-sea) and a wavy-surface case with regular plane progressive 100 m long waves (representing long-crest long-wavelength ocean swells) are considered to illustrate the capability of the LES model and study the effects of long progressive waves on the transport of oil droplet aerosols with four different droplet diameters. The simulation results and statistical analysis reveal enhanced suspension of oil droplets in wind turbulence due to strong disturbance from the long progressive waves. The spatial distribution of the aerosol concentration also exhibits considerable streamwise variations that correlate with the phase of the long progressive waves.