Abstract
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.
Highlights
In the aftermath of an offshore oil spill accident, the spilled crude oil can stay on the ocean surface for a long period of time before being restored
We model the effects of long-crest long-wavelength ocean swell waves on the aerosol transport using idealized regular plane-progressive waves [8]
Due to the relatively high computational cost associated with the current boundary-fitted large-eddy simulation (LES) model, the current study only considered one SGS surface roughness value and one wave condition chosen based on previous studies
Summary
In the aftermath of an offshore oil spill accident, the spilled crude oil can stay on the ocean surface for a long period of time before being restored During this period, frequently-occurring events at the sea surface, such as wave breaking and bubble burst, can generate a considerable amount of small aerosolized oil droplets [1], which can be further transported upward and downwind by turbulent wind in the marine atmospheric boundary layer (MABL). Frequently-occurring events at the sea surface, such as wave breaking and bubble burst, can generate a considerable amount of small aerosolized oil droplets [1], which can be further transported upward and downwind by turbulent wind in the marine atmospheric boundary layer (MABL) This process can induce serious threats to public health if the aerosols remain suspended and carried by wind over coastal ocean near high population urban cities.
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