Dispersal of Droplets over Breaking Wind Waves under the Direct Action of Wind

Abstract

This paper describes the dispersal of droplets over breaking wind waves underthe direct action of wind, based on a comparison between the actual distribution of dropletvelocity and the wind field measured in a wind-wave tank reference wind speed 16m sec^-1 The velocity distribution of droplets with a diameter d>0.81mm over breaking wind waveswas measured by Koga (1981). In this paper the wind field over breaking wind waves ismeasured by a flow visualization technique using styrofoam flakes as a tracer. The comparisonallows a clear interpretation of droplet movement over the wave profile, and shows that thehorizontal movement of the droplets of d>0.81mm is approximately determined by accelerationby the wind while their vertical movement is determined by acceleration due to gravity.These observations offer some support for the dispersion model proposed by Koga and Toba (1981).