Hsu and Yu 



Fig. 7. 300-rpm_wave growth vs. y 



are exhibited in Figs. 8 and 9. In nearly every case, experimental 

 values fall well above the theoretical line. By assuming the growth 

 to be totally dependent on F in the form of Eq. (9), we calculated 

 a ratio of the experimental and theoretical P values and present the 

 results in Table 4. The P- ratios vary from about 1 to 10. The 

 mean ratio for all frequencies and rpm's is about 3. 



The total spectral energy of the ripples in most of the experi- 

 mental cases was no more than about 20 per cent of the mechanically- 

 generated wave energy. Phillips [ 1966] argued that non-linear inter- 

 actions between waves should be weak. Hence, our procedure of 

 measuring the growth of a single wave within a spectrum should be a 

 valid means of evaluating the parameters necessary for comparisons 

 with Miles' theory. 



26 



