For the example problem, when
z = 0 ,
/ttHV cosh (4rrd/L)
C
△X(0)
T I Y I sinh2 (2nd/L) ’ ÏÏ
(ttH)2 cosh (4rrd/L)
2L
sinh2 (2rrd/L)
(ff4)2 (1.899)
2(200) (0.6705)2
(d) The first-order approximation for pressure under a wave is :
PgH
P“ V
cosh [2tt(z + d)/L]
------------------------ cos 0 — pgz,
cosh (2nd/L)
when
0 = 0 (i.e. the wave crest), cos 0 = 1,
and when
Therefore
z = — d, cosh
2tt(z 4- d)
L
cosh (0) = 1.0 .
(2) (32.2) (4)
1
„
P = ------- Z------- —— - (2) (32.2) (- 20) = 107 + 1288 = 1395 lbs/£t2
2
1.204
at a depth of 20 feet below the SWL. The second-order ternis
according to Equation 2-56 are
3
nH2 tanh (2îrd/L) cosh [4n(z + d)/L]
1
8 Pg L
sinh2 (27rd/L)
sinh2 (2nd/L)
3
1
irH2 tanh (27rd/L)
8 Pg T~ sinh2 (2nd/L) cosh
4n(z + d)
L
Substituting in the équation:
| (2) (32.2)
(-0~5569) [—2______ il
8
200
(0.6705)2 (0.6705)2
3
- - (2) (32.2)
O
n(4)2 (0.5569)
200 (0.6705)2
“ T4 Ibs/ft2.
2-46