Gj 



2.2 r 



1.8 - 



1.4 



i.O 



0.6 



' Harbor width fixed 

 b=5.72 cm 

 Harbor length varies 



Absorber No. I 

 Rlter No. I 

 Depth = 2571 cm 



• k = 4.907 



e k=4.290 



© k=4.l57 



o k=4.l!9 



e k= 3.427 



i 



0.5 



1.0 



2.0 



Figure 41. Amplification factor versus relative 

 harbor length (from Ippen, Raichlen, 

 and Sullivan, 1962) . 



Shuto all indicate that the effective length may be determined by the 

 ratio of inlet width to inlet length. 



Nishimura, Horikawa, and Shuto reported that variations in opening 

 width at the mouth of an inlet did not affect the effective length. How- 

 ever, they investigated a half -harbor width and assumed symmetry would 

 produce the same resonant motion in the half harbor as it would in a full 

 harbor. Ippen and Goda (1963) indicated this would not be true because 

 the half harbor has a asymmetric entrance one-half the width of the 

 centered entrance of the full harbor. Ippen and Goda showed that the 

 harbor entrance width determined the value of wave radiation functions 

 which are used to determine water surface elevations. 



For a fully open inlet or harbor (see Fig. 40), Ippen and Goda defined 

 resonant amplification (the ratio of an amplitude in the harbor to the 

 amplitude at the closed harbor entrance) as 



ij [(cos kL, - \\) sin kL, ) 2 + (j; 2 sin 2 kLi.] 



1/2 



(298) 



where ^ and ty 2 are wave radiation functions given in Figure 42. The 

 resonant amplification would occur where T^g/T = 1 as before. The func- 

 tions shown in Figure 42 apply to all harbor openings, where b is the 

 width of the opening. 



136 



