Laboratory Investigations on Air-Sea Interactions 



error introduced by representing the mean wave by these five terms 

 was not greater than 5 per cent in any case. 



4.3. Wave Energy 



The total wave energy (potential plus kinetic) was calculated 

 by the method developed by Dean [ 1965] through least-square-flttlng 

 an analytic stream function to the mean measured wave profiles. 

 Details of the procedure were presented by Bole and Hsu [ 1967] . In 

 order to compare the measured wave energy with Miles' prediction, 

 wave dissipation In the channel, determined experimentally under 

 the condition of no wind, as a function of fetch was added to the 

 measured wave energy. Figure 6 shows the energy ratio E(x)/E(0), 

 as a function of downstream distance for a 1.4 cps wave subjected to 

 various wind speeds, while the results In Fig. 7 are for a constant 

 wind speed (300 rpm) acting on waves of various frequencies. The 

 data was then reduced to the non- dimensional fetch F defined in 

 Eq. (10). The final results, compared with Miles' Invlscld theory, 



Fig. 6. 1.4-cps wave growth vs . x 



25 



