7.3. FIRST-ORDER WAVE GENERATION
355
sinh2fch 4- 2jfcZi
tanh kh
[sinhfch]
2
Po
it
(
tanh(0.524)
\
,
-
0.524 y sinh 2(0.524)-f-2(0.524) J [sinh(0-524)]
/ pghS^
1.202
I T J
which gives the mean power requirement of
n
(pghS2 o\ /n
/9800 JV/m3(0.25m)(0.115m)2\ n
.
Po =
■--- (0.377) = ----------------- (0.377)
\ 1
J
\
2 s
/
Po = 6.1 (^y^) /m = 6.1 W/m (1.4 (^-y^)/fi)
Flap-Type Wavemaker. From Eqn. 7.59 the wave height-to-stroke ratio for a flap-type
wavemaker is
H _
4sinhl:ft
So
sinh 2kh 4- 2kh
sinh kh 4- ttU — cos^
kh
H _
4sinh(0.524)
So ~ sinh 2(0.524) 4- 2(0.524) [
sinh(0.254) 4- , ~c(l - cosh(0.524))
I U.0Z4 I
ff
2 191
— = -———(0.548 - 0.268) = 0.267
So
2.297v
'
and the required piston stroke at z = 0 is
So = —— =
= 22.5 cm (8.9 in)
0.267
0.267
----------or about twice the stroke required of the piston-type wavemaker.
The mean power to generate this wave with a piston-type wavemaker is found
horn Eqn. 7.82 with I = 0, or
1 2
x = — (
tanh------- 'l [sinh kh 4- 7^(1 - cosh kh)\
(pghs%\
kh \sinh 2kh 4- 2kh/ L
kh
J
\ t )