Entering Table C-2 again, it is found that when
z — t?c>2 ~ 2.48 feet,
cosh
cosh
2;r(z + d)
L
4tt(z + d)
= cosh [240.1124)] = 1.260,
cosh [440.1124)] = 2.175 .
When
z = rit 2 = ~ 1.52 feet,
cosh
cosh
24z + d)
L
= cosh [240.0924)] =
44z + d)
L
= cosh [440.0924)] = 1.753 .
Thus, the value of u
to second-order theory is
at a crest and trough respectively according
4
1.260
u ? = - (32.2) (0.0418) --------c>2
2
1.2040
4
1.174
u. 7 =------(32.2) (0.0418) ------- —
*>2
2
1.2040
3
4
2.175
(23.9) ------ = 3.6 ft/sec ,
0.202
3 I— V
+ 4 \200/
1-753
(23.9) q
=* - 2.0 ft/sec
(c) To find the horizontal distance that a particle moves during one
wave period at z = 0, Equation 2-55 can be written as:
△X(z)
/îtH *'• C cosh [44z + d)/L]
T
\ L
2
sinh2 (27rd/L)
where AX(z) is the net horizontal distance traveled by a water
particle, z feet below the surface, during one wave period.
2-45