From Figure 2-11, entering with H/d and T/g/d', determine the square 

 of the modulus of the complete elliptical integrals, k^. 



F = 1 - 10-^-9-y . 



Entering Figure 2-12 with the value of k^ gives 



L=S^tanh(^'= 266.6 ft. 



To check whether the wave conditions are in the range for which 

 cnoidal wave theory is valid, calculate d/L and the Ursell 

 parameter, L^H/d^. 



^ ^° = 0.0363 < - O.K. , 



L 275.7 8 



L'H 1 /"i = 190 > 26 O.K. 



d^ idIL? \d 



Therefore, cnoidal theory is applicable, 

 (b) Wave celerity is given by 



C = - = ^^ = 18.38 ft/sec. 

 T 15 



while the Airy theory predicts 



L 266.6 



C = - = = 17.77 ft/sec. 



T 15 



Thus if it is assumed that the wave period is the same for Cnoidal 

 and Airy theories then 



^Cnoidal _ ^Cnoidal ^ 

 ^Airy ^Airy 



2-57 



