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CHAPTER 7. LABORATORY WAVE GENERATION
Po
tt
(
tanh(0.524)
pghsj ) = 0.524 y sinh 2(0.524) + 2(0.524)
• sinh(0.524) +
“ cosh(0.524))
0.118
1.202
0.098
which gives the mean power requirement of
pghS^X
/9800 N/m3(0.25 m)(0.225 m)2\ ,
1 (0.098) = ( ----------------2s
------------ — ) (0.098)
Po= 6.1
which is the same mean power requirement as the piston-type wavemaker.
7.3.2 Variable-Draft Flap-Type Wavemaker
Hyun (1976) gave the first-order wavemaker solution for the case of a flaptype wave board hinged on a sill a distance I above the bottom of a twodimensional wave flume as illustrated in Figure 7.5. These types of wave
boards are efficient for generating deepwater waves where the orbital excursions are minimal at the depth of the hinge, and they can accommodate the
introduction of current flows through manifolds placed in the lower part of
the sill.
The first-order solution for the variable-draft flap-type wavemaker is the
same as found for the flap-type wave board hinged below the bottom with
the exception that we now specify the board motion as
X(z,0 = /(z)X(0
<7-86)
with
/( * )
—
[for 0 > z > —(h. — /)]
(7.87)
and
M = o
[for z < — (/i — /)]
(7.88)