ERDC/CHL CHETN-I-64
September 2001
distribution of frequencies. For each input spectrum specified, the additional parameters
of wind speed, wind direction, and water level are required. The wind information is
only used if the wind input option is selected. Winds blowing offshore are neglected
because of the half-plane model assumption. Tide information is specified relative to the
bathymetry datum used to generate the depth grid. Multiple wave model runs can be
executed by inserting multiple spectra in the input file. STWAVE will run multiple cases
in a quasi-time stepping mode.
d. Current fields. Current field input is required only if the wave-current interaction option
is selected. Current information is specified with x- and y-components of the currents at
each grid cell. Currents can be interpolated from output of a circulation model. SMS
provides algorithms to interpolate between circulation and wave model grids. A single
current field can be used for all input spectra or the number of current fields must equal
the number of input spectra.
STWAVE model output includes:
a. Fields of wave height, period, and direction. For each input spectrum, STWAVE outputs
fields of significant wave height (defined as the zeroth moment of the spectrum), peak
period, and mean direction. The parameters are provided for all grid cells. The mean
directions are given in the STWAVE local coordinate system, but can be visualized in
global coordinates within SMS.
b. Spectra at selected grid cells. For the grid cells selected in the model parameter input,
STWAVE outputs the full two-dimensional (frequency-direction) spectrum. The spectral
output may be used for model validation with field measurements or as input to a nested
STWAVE run or a local-scale wave model. STWAVE also writes out the significant
wave height, peak period, and mean direction for the selected grid cells to a separate
output file. This summary output is useful for validation or input to other engineering
calculations.
gradients are provided for all grid cells if the radiation stress option is selected. These
stresses can be used as input to a circulation model to calculate wave-driven currents and
setup.
d. Fields of breaker indices. For applications to sediment transport, navigation, and
structure design, it is useful to know the location of wave breaking. The breaker index
output notates grid cells where waves are breaking with an index of 1 and cells without
breaking with an index of 0.
All STWAVE input and output are specified in metric units and ASCII format. SMS provides
the option to convert input from English units to metric and visualize output in English or metric
units. The STWAVE user's guide provides file formats for all input and output files (Smith,
Sherlock, and Resio 2001).
SMS USER INTERFACE: The SMS user interface is a powerful tool for generating and
visualizing STWAVE input and visualizing STWAVE output. SMS can be used to run
STWAVE, but is not required. However, SMS can significantly reduce the time and effort
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