Figure 40. Plan view of inlet. 



waves. It is assumed in this case that B x ■* ». The experimental results 

 of Ippen, Raichlen, and Sullivan are shown in Figure 41, where k is the 

 wave number 2tt/L. The results are for a fixed inlet width and varying 

 wavelength, the variation in the curves illustrating the dependence of 

 the results on the ratio of wavelength to inlet width, particularly for 

 short, wide inlets. 



Each curve in Figure 41 was obtained by varying the inlet length for 

 a fixed wavelength. The results were dependent upon the efficiency of 

 the wave filters and wave absorbers used in the experiments. Using 

 equation (293) to define Tj , 



kL>, = T 



2 T 



(296) 



Therefore, Figure 41 shows that the maximum amplification occurs where 

 T]7T < 1. Ippen, Raichlen, and Sullivan did not explore the amplifica- 



tion for shorter period waves; i.e., Tj/T - 3, 5, 7, 



etc. The maxi- 

 mum amplification occurring where T 2 /T < 1 is equivalent to resonance 

 for a longer inlet. It can be assumed, therefore, that the inlet has an 

 effective length L g extending into the open sea; i.e., since a node 

 does not exist at the entrance, L g > Lj and the effective primary period.. 

 T le , is 



le 



4L, 



(297) 



The length L , is defined by equation (297) if it is assumed that 

 T, /T = 1 where maximum amplification occurs. 



Nishimura, Horikawa, and Shuto (1971) carried out similar experiments 

 for an inlet with the entrance partially closed by a breakwater. They 

 also found that the inlet had an effective length greater than the actual 

 length. Ippen, Raichlen, and Sullivan (1962) and Nishimura, Horikawa, and 



135 



