Damping Region
Spatially
Homogenous
Region
θmax
θmax
Wave Generation Boundary
Figure 7.
Sketch showing spatially homogenous region for multidirectional
waves
Step 8. Simulation Parameters
Duration of Numerical Simulation (s) This is equal to time required for the
storm waves to propagate from the wave generation boundary to the farthest
points of interest in the model area and establish steady-state conditions, i.e.,
warm-up period plus the duration of the synthesized or input time record
specified in Step 6.
Simulation Time-Step (s) The time-step should be selected based on the
stability considerations, i.e., the Courant number Cr has to be less than 1.0:
2 2 1
1
Cr = C ∆t 2 + 2
< 1.0
∆x
∆y
where C is the phase velocity calculated using the maximum water depth
(hmax) and the average zero-crossing period of the incident waves. It is
recommended that the Courant number be kept within the range 0.5 to 0.7,
which typically corresponds to 30 to 50 points per wave period. For plunging
waves on steep slopes, it may be necessary to use up to 100 points per wave
period to simulate the rapid changes in wave shape irrespective of the
Courant number.
Chezy Coefficient Bottom friction factor with a default value of 30. Should
be kept between 20 and 1,000.
Model Equations Option (Weakly Nonlinear/Fully Nonlinear) Select either
weakly nonlinear model of Nwogu (1993) or the fully nonlinear model of
Nwogu (1996). The fully nonlinear model is computationally more intensive
35
Chapter 4 Setting Up and Running BOUSS-2D
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