3. Referral to Prototype Conditions . 



Sinusoidal flow at values of a, T selected in the laboratory is 

 approximated at the seabed under various combinations of wave height (H) 

 and length (L) and depth of water (h) , providing that the waves do not 

 break. The condition that shallow-water waves be nonbreaking is, approx- 

 imately (eq. 2-90 in U.S. Army, Corps of Engineers, Coastal Engineering 

 Research Center, 1977) , 



h/H > 1.28 . (17) 



For sinusoidal waves in shallow water, with h/L << 1, 



2a sinh(2TT ~) ^ 4Ta ^ (18) 



and the celerity is, approximately, 



L/T ~ Vgh . (19) 



Equations (18) and (19) provide 



h/H :. ViLL 

 4ir a 



so that, with equation (17), for nonbreaking waves. 



v/gh $- (2.56) 2i: J = 2.56 U . (20) 



With U less than 77.1 centimeters per second, as in these experiments, 

 any value of h greater than 40 centimeters ensures nonbreaking waves. 



38 



