Table 4-4. Values 



of (dp) 



a function of T„ and DF. 

 max r 













Tp 





DF 







2.0 



3.0 



4.0 



5.0 





( P/max 





(s) 





(ft 







20 



20.0 



8.9 



5.0 



3.2 



25 



31.2 



13.9 



7.8 



5.0 



30 



45.0 



20.0 



11.3 



7.2 



45 



101.0 



45.0 



25.3 



16.2 



60 



180.0 



80.0 



45.0 



28.8 



75 



281.0 



125.0 



70.3 



45.0 



90 



405.0 



180.0 



101.0 



64.8 



120 



720.0 



320.0 



180.0 



115.0 



180 



1,620.0 



720.0 



405.0 



259.0 



210 



2,205.0 



980.0 



551.0 



353.0 



240 



2,880.0 



1,280.0 



720.0 



461.0 



must be used to obtain the correct values for wave velocity, the equa- 

 tions Cfrom eqs. 4- 16b and 4- 17b) 



V, = ihY" 



27rd„DF\ 



1/2 



and 



tanh 



27rd, 



1/2 



', - (^X 



1/2 



tanh 



27rd\l/2 



/ 27rd„DFY/2 

 tanh B — I 



\ 



must be used. The use of these relationships does not provide similar- 

 ity of refraction for those conditions of d/A where the wave velocity 

 is not given accurately by the relation V = (gd)-^'^, as explained above; 

 however, this use does ensure that the wavelengths on the model are scaled 

 accurately by the horizontal linear scale (L^) . This ensures accurate 

 simulation of wavelengths relative to harbor-basin dimensions, which en- 

 sures correct simulation of modes of oscillation in the basins for all 

 wave periods and, therefore, the occurrence of resonance at correct wave 

 periods. 



The use of the applicable equation (4-13) or (4-17a), if the equation 

 V = (.gd) ^/^ can be used with sufficient accuracy in wave velocity calcula- 

 tions, also ensures accurate simulation of wave diffraction. However, 

 if a distorted-scale model is operated in such a way as to obtain accurate 



23 



