Tangential stress beneath wind-driven air–water interfaces
Michael L. Banner a1 and William L. Peirson a1a1 School of Mathematics, The University of New South Wales, Sydney, Australia, e-mail: M.Banner@unsw.edu.au
The detailed structure (click here) of the aqueous surface sublayer flow immediately adjacent to the wind-driven air–water interface is investigated in a laboratory wind-wave flume using particle image velocimetry (PIV) techniques. The goal is to investigate quantitatively the character of the flow in this crucial, very thin region which is often disrupted by microscale breaking events. In this study, we also examine critically the conclusions of Okuda, Kawai & Toba (1977), who argued that for very short, strongly forced wind-wave conditions, shear stress is the dominant mechanism for transmitting the atmospheric wind stress into the water motion – waves and surface drift currents. In strong contrast, other authors have more recently observed very substantial normal stress contributions on the air side. The availability of PIV and associated image technology now permits a timely re-examination of the results of Okuda et al., which have been influential in shaping present perceptions of the physics of this dynamically important region. The PIV technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements, and allows reliable determination of the fluid velocity and shear within 200 μm of the instantaneous wind-driven air–water interface....
The north Atlantic is difficult, but, severe weather with wind - wave interaction is common. To have this occur in the western Atlantic is mostly unheard of.
Wave height alone will not necessarily cause severe conditions for ocean going vessels. The multiple directions of air and resultant water is when these conditions are perfect for rouge waves.
