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ABSTRACT 



The processes of wave and current development resulting from wind action 

 on initially standing water have been investigated in a wind- water tunnel. 

 The mean air flow over wavy water was examined along with the variation of 

 several properties of the water motion with fetch, water depth, and wind 

 speed. Measurements of phase speed and length of significant waves, the 

 standard deviation of the water surface, the average surface drift, the auto- 

 correlation of surface displacement and the frequency spectra are reported. 

 The experimental results indicate that (a) the air motion in the channel 

 follows a three dimensional pattern characteristic of wind tunnels of rectangular 

 cross-section; (b) wind waves generated in the channel travel downstream at 

 approximately the same speed as gravity waves of small amplitude, provided the 

 effect of the drift current is taken into account; (c) the average drag co- 

 efficients for the action of the wind on the water surface increase with in- 

 creasing wind speed, and these data are reasonably consistent with results of 

 previous investigators; (d) the autocorrelations and frequency spectra indicate 

 that the wind waves in the channel consist of nearly regular primary waves on 

 which are superimposed smaller ripples; (e) energy in the high frequency range 

 in the spectra tends to approach an equilibrium distribution while the lower 

 frequency components continue to grow with increasing fetch; and (f ) a 

 similarity shape for the frequency spectra develops. The experiments in this 

 study were not intended to model the processes of interaction between the 

 ocean and the atmosphere. Nevertheless, the small waves generated in the chan- 

 nel appear to be at least qualitatively related to the development of waves 

 on much larger bodies of water. 



