constituted permutations of the following target parameter values: *H*mo = 3.7

and 5.5 cm, *T*p = 0.7 and 1.4 s, wave direction perpendicular to the jetties, and

gauges placed around the inlet with the main objective of studying wave

breaking and to determine the wave height decay.

Here, four runs were simulated to investigate the model performance,

especially regarding the capability of (a) the wave action equation (Equation

1) to reproduce the wave transformation in the presence of a current using

linear wave theory, (b) the criterion for incipient breaking (Equation 12) to

describe waves propagating on a current and in limited water depth, and (c)

the generalization of Dally's model (Equations 13-16) to predict the energy

dissipation due to wave breaking on a current.

Table 1 summarizes the runs selected for simulation representing both

long- and short-period wave cases, as well as, weaker and stronger currents.

The values given in the table are the target values, whereas for the model

simulations the actual measured wave heights and periods in the horizontal

portion of the basin (just off the wave maker) were employed (see

Appendix A in Smith et al. 1998). The conditions of the CHL-I experiments

were such that blocking should not occur according to the criterion based on

linear theory (Equation 19) with the peak spectral wave period characterizing

the waves. The measured wave heights in the experiments indicate that this

was indeed the case.

5

0.055

1.4

0.14

7

0.055

1.4

0.24

9

0.055

0.7

0.14

11

0.055

0.7

0.24

Standard values were employed for the coefficients in the wave

Γ = 0.4. Waves were represented by a Monte-Carlo simulation by assuming

a Rayleigh pdf in the offshore (i.e., in the horizontal portion of the basin

where wave breaking and the current were negligible). NMLong-CW

normally provides the root-mean-square (rms) wave height as output since

this quantity may be calculated in a straightforward manner without having to

save all intermediate calculation results from individual waves in the

ensemble representing the offshore pdf. However, Smith et al. (1998) only

reported the energy-based significant wave height *H*mo, so the entire

simulated series of waves at each location were run in the present cases to

compute the significant wave height by taking the mean of the one-third

largest waves (assumed to be equal to the spectrally determined zero-moment

wave height *H*mo reported for the experiments).

The measured current at six locations defined the input cross-shore

current distribution. Linear interpolation was employed between the

measurement points to obtain values at the different model grid points.

However, because no measurements of the current were made at some

distance seaward of the inlet mouth (except close to the wave maker where

26

Chapter 4 Verification of Wave Model

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