

TM No. 377 



5W <?t 



(11-12) 



As with particle velocity, for intermediate waves the particle displacement 

 'in the vertical is zero at the bottom. 



Any sensor will have certain limitations such as the threshold velocity, 

 time, and scale response. It is reasonable to assume that the wave motion 

 detector can measure current velocities down to 10 cm sec~l, and that the 

 dimensions of the detector will preclude the sensing of turbulent "eddies" 

 less than 10 cm in length (or diameter). 



An estimate of the wave magnitudes that might provide such threshold 

 parameters and of the range of depths at which these threshold values occur 

 can be made by using equations II-5> 7, 9> and 11. Neglecting the time 

 variable terms, one can assess the maximum value of the amplitude of the 

 oscillating functions at various depths. Table II-l is a summary of observed 

 and theoretical relationships for Surface wind waves. Columns A through E 

 were taken from a table presented by Stewart (1961), and the parameters 

 listed therein are strictly estimates from large amounts of observed data. 

 The wind speeds given in the table occurred for a long enough interval to 

 produce waves in a steady or fully developed condition. 



TAS1E II-l 

 Summary of Observed and Theoretical Relationships for Surface Waves 



1 = from Intermediate Wave Theory (see equations II- 7 and II-8) 



17 



