NCOMING WAVE FRONTS 



' ELLIPTICAL JWAVE FRONTS \ / 



Figure 194. Wave pattern generated by Bowley wave barrier concept 

 of floating breakwater (after Bowley, 1974). 



Bowley (1974) investigated each of the flexibility criteria using three 

 primary module types and more than 500 combinations of wave heights, wave- 

 lengths, and random seas (Pierson-Moskowitz spectrum model). The experimental 

 study was conducted in towing tank facilities (Fig. 195). Much of the data 

 obtained in the study were directed toward the evolution of the system for 

 some degree of optimization under technical and economic constraints. Much of 

 the previously reported data are for periodic wave input. However, the power 

 spectral density versus frequency display is probably better because it 

 approximates the conditions that the system will be subjected to in the open- 

 ocean environment. Bowley (1974) used both types of wave climates in the 

 experimental investigation of the wave barrier system acting as an "air 

 spring." Bowley 's extensive theoretical analysis of the motion of a single 

 module provides little useful information on the performance of the modules 

 because of the extremely complicated interactive, nonlinear process. It does, 

 however, help to understand the relative significance of the primary design 

 variables for a single module. 



Figure 196 provides an indication of row effectiveness for the larger 

 scale modules. In this test, four rows in the full array were anchored across 

 the tank in a sequence of three buoys in the first row, two in the second, 

 three in the third, and two in the fourth. The removal of the last two rows 

 did not affect the function of the system until larger wave inputs were 

 applied. The system is such that the buoy size can be changed with the row 

 position away from the upwave direction (because each successive row must 

 function in a different wave climate); however, standard sizes would probably 

 be more economical to fabricate. 



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