presented in this report are given as positive numbers, even though the flow is in
the negative y-direction.
Wave Generators
Regular and irregular waves are generated using four repositionable, piston-
type wave generators. The waves are accurately generated using a digitally
controlled servo electric drive system to control the position of the wave boards.
Each wave generator has a 7.62-m-long wave board, so all four systems generate
a total wave front of 30.5 m in length. The wave generators are synchronized to
create unidirectional long-crested waves. Figure 5 is a photograph of the wave
generators during a performance test to determine the maximum wave height that
can be generated at various wave periods. The wave generators can be oriented at
various angles ranging from 0 to 20 deg with respect to shore-normal. In Figure 4,
the wave generators are positioned at 10 deg to shore-normal. For oblique angles
of wave attack, the wave generators are phase-shifted to maximize the cross-
shore dimension of the testing region. End baffles, located between each
adjacent wave board, are used to guide the waves and prevent the formation of
spurious waves caused from wave diffraction from the ends of each wave board
and from wave energy reflected from the wave absorber located behind the wave
generators.
Figure 5.
Synchronized wave generators creating long-crested waves
A performance curve for the wave generators is given in Figure 6 for a water
depth of 0.9 m at the wave generators. There are six curves in this figure. The
cresting-limit curve is based on linear wave theory for H/Lo = 0.142, where H is
7
Chapter 2
Overview of the Laboratory Facility
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