From Figure 2-11, entering with H/d and T/g/d\ détermine the square
of the modulus of the complété elliptical intégrais, k2.
V = 1 - 10 -3.95
Entering Figure 2-12 with the value of k2 gives
-^=190,
or
190 d3
H
L = 275.7 ft.
From Airy theory
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^/d3.
d
L
10
275.7
1
= 0.0363 < - O.K. ,
8
d3
1
(d/L)3
H\
d/
190 > 26 O.K.
Therefore, cnoidal theory is applicable.
(b) Wave celerity is given by
— = 2757 = 18 38 ft/sec
T
15
while the Airy theory predicts
266.6
------ = 17.77 ft/sec.
15
Thus if it is assumed that
and Airy théories then
the wave period is the same for Cnoidal
C
'Airy
2-57