and post-processing tools, and thus it is widely used worldwide. References providing
details about this model and its capabilities, and application examples may be found at
Simulations were performed for wave conditions observed during storms at the site.
Due to space limitations, results are presented for only one wave condition. The
simulated incident condition was for regular waves from SSW (wave direction 210 deg
azimuth) with height 3.3 m (10 ft) and period T=10 sec. Waves in this inlet appear to be
irregular and short-crested seas with directional spreading, i.e., spectral waves. In this
simulation, we assumed waves to be monochromatic (single frequency swell) for
promoting visualization, and the wave-current interaction was omitted under assumption
of weak current for existence of Threes. The bathymetry grid was developed from a U.S.
Army Corps of Engineers SHOALS (Lidar) survey conducted on July 7, 2000 (Figure 6),
and displays a large shoal on the northwest end of the west jetty. The modeling domain
consisted of an offshore region bounded by a semicircle (Figure 6), the east and west
jetties, and the shoreline on both sides of the inlet. At the termination of the jetties, the
attached coastlines define the inlet boundaries starting from throat area through the inlet's
side banks that connect inlet with the bay area. These boundaries were specified in the
CGWAVE modeling to be 70% reflective in the throat and along the inlet side banks.
The boundaries of back-bay area were fully absorbing to avoid potential wave reflection
due to finite extent of the bay that was modeled. This would not have been necessary if
the back-bay region had been modeled in its full extent. An artificial down-wave
boundary was introduced at a close distance from the end of inlet to reduce the modeling
domain and shorten CGWAVE computational times. By doing so, waves pass through
the artificial boundary and are prevented from reflecting back into the reduced bay area
or into the inlet.
Results of the predicted wave field in the computational domain are shown in Figures
7-12. The model simulations displayed the observed pattern of Threes, i.e., waves
impinging on the east jetty, reflecting from it and turning northwesterly to head toward
the end of the left side bank, and again reflecting from there heading toward the bay.
This can be seen beautifully in the animation of wave surface profile that was generated
by the SMS. The animation combines wave amplitude and wave phase (perpendicular to
the direction of wave advance), and displays the wave front in time-domain as
consecutive snapshots or frames. A sequence of frames over a wave period is then
animated in the SMS for viewing progression of waves through Shinnecock Inlet.
Figures 7 and 8 display the two-dimensional wave field distribution in the inlet.
These are snapshots taken from animation files showing wave surface elevation and wave
direction together. The intensity of contours in these figures (black and white) is
proportional to the wave amplitudes (heights) computed by the CGWAVE model. The
vectors represent the spatially variation in the wave directions. Because of the strong
reflection of waves from the jetties and inlet side banks, wave direction in such a
confined inlet is strongly varying and appears somewhat confused, and thus the waves