Comparison with Prototype 



107. Representative profile comparisons between prototype and model after equal numbers of waves 

 are given in prototype dimensions on Figure 13. A complete set of profile comparisons is given in Figure E3 

 in Appendix E (Test T04 versus Prototype). 



108. The net effect of increased wave height after 40 waves is slightly more erosion of the berm and 

 more transport of sediment into the deeper portion of the profile. Calculated RMS variation between 

 prototype and model after 40 waves was 0.64 m (compared with 0.70 m for test T03). 



109. The model comparison to prototype after 370 waves is judged as being very good with an RMS 

 variation of 0.38 m (compared with 0.49 m for test T03). At this point, more of the berm had been eroded 

 than in test T03 (see Figure 10), and a good correspondence is also seen in the surf zone and in the 

 offshore region. 



110. The center-line profile after 1,650 waves, when near-equilibrium had been achieved, showed a very 

 favorable reproduction of the prototype profile development. The RMS variation calculated for this 

 comparison was 0.30 m (compared with 0.44 m for test T03), whereas comparison with the model average 

 profile at 1,650 waves (Figure 12) produced an RMS variation of 0.36 m (0.40 m for test T03). 



111. Test T04, with the wave height increased 10 percent over what should represent the equivalent 

 scaled model wave height, produced better comparisons to the prototype case. The increased wave-induced 

 water velocities in the offshore region appear to have transported sediment in the model to a greater 

 offshore depth that more closely corresponds to the prototype. This increased sediment demand was met 

 by the removal of more sand in the nearshore region; consequently, better profile reproduction, both in the 

 final equilibrium and in the developmental stages, was achieved. 



Experiment Serendipity 



112. The fortunate discovery that a 10-percent increase in model wave height provided better 

 reproduction of prototype behavior merited further examination. The possibihty that reported prototype 

 wave conditions were 10 percent less than actually generated was immediately discounted given the care 

 with which the prototype experiments were conducted. Instead, the differences between the prototype and 

 model in the region off'shore of the breakpoint bar were examined. 



113. It was shown in Part II that the fall speed parameter scaling criterion represented a special case 

 of the criterion developed from maintaining similarity of Xie's (1981, 1985) parameter (see Equation 8). 

 Ideally, the scaling criterion given by Equation 10 should be preferred over the selected criterion used in 

 this study. However, as was pointed out, this criterion is impossible to satisfy throughout the modeled 

 regime. To examine the variation in Xie's parameter between the prototype and model, idealized 



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