Table 5. Repeatability Test RMS Variations 





Model RMS 



Prototype Equivalent 



Profile 



Variation 



RMS Variation 



Waves 



in. 



m 



40 



1.9 



0.36 



370 



1.1 



0.21 



1650 



1.0 



0.19 



Irregular Wave Validation Test 



Experiment Setup 



119. Following completion of all regular wave testing in the 6-ft flume, the authors requested and 

 received from Drs. Uliczka and Dette prototype-scale test data stemming from irregular wave tests 

 conducted in the GWK. The prototype tests requested were conducted using the same sand (0.33 mm) as 

 was used in the regular prototype-scale wave tests discussed earlier in this report. The primary difference 

 between the two cases was that approximately three times as much sand was used in the irregular wave 

 tests. This sand was a sufficient amount to prevent exposure of the sloping concrete revetment during 

 testing as occurred during the regular wave tests. Consequently, the irregular wave tests took significantly 

 more time to approach equilibrium, and in fact, had not reached equilibrium after nearly 7,000 waves 

 (compare with equilibrium being reached after 1,600 waves when the revetment was exposed in the regular 

 wave tests). 



120. The irregular waves used in the prototype test series were a time series realization of a JONSWAP 

 spectrum having an Hmo equal to 1.5 m and a spectral peak period of 6.0 sec. As in the regular wave tests, 

 water depth was 5.0 m. These waves were scaled to model size using the same scaling determined for the 

 regular wave tests. An irregular wave train was generated using CERC software that reproduced the 

 prototype spectral parameters of significant wave height and peak period. The spectral width parameter, 

 7, in the JONSWAP spectrum was set equal to 3.3. Fine adjustment to the time series amplitude was 

 made prior to testing to assure accurate reproduction of the scaled waves. 



121. Examination of the extent of profile erosion documented in the prototype test indicated that 

 doubling the volume of sand used in the previous regular wave tests would be sufficient to prevent exposure 

 of the revetment and still provide adequate sand cover of the sloping revetment. Therefore, rather than 

 increasing the sediment in the flume by a factor of three, it was increased by only a factor of two (the 



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