1.20E+01
1.00E+01
8.00E+00
6.00E+00
4.00E+00
2.00E+00
0.00E+00
0.00E+00 5.00E-02 1.00E-01 1.50E-01 2.00E-01 2.50E-01 3.00E-01 3.50E-01 4.00E-01
Frequency (Hz)
Figure 1. Sample one-dimensional wave spectrum
the peak of the spectrum. The wave height (significant or zero-moment wave
height) is equal to four times the square root of the area under the spectrum. For
the example spectrum given in Figure 1, the peak frequency is 0.105 Hz, the peak
period is 9.5 sec, and the wave height is 2.8 m. STWAVE is based on the
assumption that the relative phases of the spectral components are random, and
thus phase information is not tracked (i.e., it is a phase-averaged model). In
practical applications, wave phase information throughout a model domain is
rarely known accurately enough to initiate a phase-resolving model. Typically,
wave phase information is only required to resolve wave-height variations near
coastal structures for detailed, near-field reflection and diffraction patterns.
Thus, for these situations, a phase-resolving model should be applied.
Model Assumptions
The assumptions made in STWAVE version 3.0 are:
plane model, meaning that wave energy can propagate only from the
offshore toward the nearshore (87.5 deg from the x-axis of the grid,
which is typically the approximate shore-normal direction). Waves
reflected from the shoreline or from steep bottom features travel in
directions outside this half plane and thus are neglected.
4
Chapter 2 Governing Equations and Numerical Discretization
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