ERDC/CHL CHETN-I-69
March 2005
they are defined. The Damping and Porosity values can be specified using boundary conditions on
cell strings or selected from the scalar functions. The Current is selected from the available vector
functions.
(2) Time control. The interface displays the recommended values for Duration and Time-step in
parentheses. The Courant number (Nwogu and Demirbilek 2001) is computed based on the cell size
and the specified time-step. A value 0.3 to 0.5 is recommended.
(3) Laminar and turbulent viscous flow coefficients for porosity. The Turbulent value ranges
from 0.0 to 3.6 with a default value of 2.4. The Laminar value ranges from 0 to 1,500 with a default
value of 800. Stone size represents the characteristic stone size (d50) in meters of the breakwater
armor layer and must be greater than zero.
(4) Grid information. This section displays the attributes of the active grid and cannot be edited
from within the Model Control dialog.
(5) Parameters. The Tidal Offset value is the elevation of the water level relative to the still-water
level. Check the Enable Wave Runup box to enable wave runup calculations. A minimum flooding
depth must be specified for runup calculations with a default value of one-hundredth of the wave
height. The Chezy coefficient ranges from 0.0 to 1,000.0 (default = 50) and the Smagorinsky
coefficient must be between 0.0 and 2.0 (default=0.2). The choice for Nonlinear Option is either
Strong or Weak. Check the Enable Wave Breaking box to enable simulation of wave breaking and
enter a value for the Turbulent Length Scale with a default value equal to the wave height.
(6) Spatial output options. BOUSS-2D can output spatial data across the grid. These include the
constant functions Significant Wave Height and Mean Currents, as well as the temporally varied
values of Water Surface Elevation and Velocity. In this section of the dialog, the user defines which
files are to be created. The Override default file prefix box allows the user to specify a file name for
these solution files. The default file prefix is the file name of the .par file. By checking Output WSE
and/or Output Velocity the user tells the model to output the time varying data sets. By default, the
model will save data at each time-step. This would result in huge files, so normally the user will
select the Override Default toggle. This enables the Begin Output, End Output, and Step controls.
The Begin & End Output values must be greater than 0.0 and less than the run duration. Also, the
begin time must be less than the end time. The Step control determines how often the model will
save time-varying output. SMS computes the number of frames and an approximate amount of
memory required for the resulting data sets.
h. Defining wave conditions with wavemaker(s): The principal input boundary condi-
tion to the BOUSS-2D model is the wave conditions at wavemaker(s). The BOUSS-2D model
requires at least one wavemaker. The properties of a wavemaker are defined in the BOUSS-2D Wave
Generator dialog (Figure 10). This dialog is accessed selecting a cell string with the Select Cellstring
tool and choosing the BOUSS-2D | Assign BC menu item. In the BOUSS-2D Boundary Conditions
dialog, the Wave Maker option is selected and the Options button is clicked. This brings up the
BOUSS-2D Wave Generator dialog.
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