Study of sea spray impact on air-sea momentum flux using a Lattice-Boltzmann method for fluid dynamics

Accurate predictions/parameterizations of air-sea momentum and heat fluxes are important because they provide boundary conditions for atmospheric, oceanic and coupled ocean atmosphere models. In particular, tropical cyclone model prediction is very sensitive to air-sea flux parameterizations under high wind conditions. Recent field observations suggest that the momentum flux (drag) coefficient tends to be much lower than the existing bulk parameterizations at very high wind speeds. One possible reason for this drag reduction is the effect of sea sprays generated in great amount by surface breaking waves in high winds. In this study we investigate how a large amount of sea spray droplets may affect a turbulent shear flow just above the air-sea interface by using the Lattice-Boltzmann method for fluid dynamics. We develop novel numerically efficient approaches to resolve two-phase flows with a large density ratio (such as air and water), and to simulate a turbulent shear flow including the feedback force from spray droplets to surrounding air.