HR: 0800h
AN: OS41D-0501    [Abstracts]
TI: Oil Dispersion By Breaking Waves And Wind/Wave Induced Currents
AU: * Brovchenko, I
EM: brovchik@env.kiev.ua
AF: Institute of Mathematical Machine and System Problems, Glushkov av. 42, Kiev, 03187 Ukraine
AU: Maderich, V
EM: vlad@env.kiev.ua
AF: Institute of Mathematical Machine and System Problems, Glushkov av. 42, Kiev, 03187 Ukraine
AB: Oil spilled at sea often entrained by breaking waves in stormy conditions and forms clouds of oil droplets that are dispersed by subsurface turbulence and shear currents. In this paper we consequently consider main mechanisms of oil dispersion - wave breaking, diffusion by turbulence generated by wind currents and Stokes drift, formation of oil droplet sizes specter by breaking waves and transport of dispersed oil in the surface layer. The joint action of wind stress, Stokes forcing and wave breaking with use of time-dependent 1D model with two-equation turbulence closure was simulated. The model equations are derived by horizontal averaging of Langmuir circulation model (McWilliams et al., 1997). The wave-breaking layer with thickness of half significant wave height was included into consideration. An injection of turbulence by penetrating breakers in this layer was parameterized by source terms in the turbulent kinetic energy and dissipation rate equations. The Monte-Carlo simulations of intermittent mixing support assumption that observed (Agarwal et al., 1992) lognormal distribution of dissipation rate is associated with breaking of waves in many scales. The calculations show the essential influence of Stokes drift and wind waves breaking on the mixing process. The results of simulations were applied to modeling of formation of oil droplet sizes spectra under the breaking waves. Almost all statistical models of break-up of an immiscible fluid immersed into a turbulent flow were not able to reproduce observed distribution of oil droplet size. Instead, the new model of the breakup based on Kolmogorov (1941) approach was proposed to reproduce observed lognormal distribution of oil droplet sizes. The calculations show that knowledge of mean characteristics of breaking wave field is not enough to simulate the breakup and entrainment of liquid and gas in the surface layer. The subsurface dispersion of entrained oil is governed both wind driven and wave driven currents. The detailed results of simulations of oil dispersion in the wave enhanced layer for stormy conditions by linked model of surface turbulent layer and 3D Lagrangian model of oil spill are presented.
DE: 4251 Marine pollution
DE: 4255 Numerical modeling
DE: 4546 Nearshore processes
DE: 4568 Turbulence, diffusion, and mixing processes
DE: 4572 Upper ocean processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting