R = <R /R > 0.95 = 0.89 (0.95) = 0.84 . (145) 



P m p 



The two estimates for the reflection coefficient (eqs. 138 and 145) 

 are in close agreement and they may be considered quite accurate since 

 they correspond to values of |A|/(d tang ) = 1.6 and d/h = 0.107 which 

 are within the range of the data presented in Figure 22. The value of 

 the Reynolds number defined by equation (131) is 1.1 X 10*+. This 

 demonstrates that the flow in the model and therefore also in the 

 prototype is fully rough turbulent and indicates that a Froude model will 

 reproduce the energy dissipation on the rough impermeable slope correctly. 



As discussed in conjunction with the numerical example presented in 

 Section II, the numerical example in this section accounts for the 

 external energy dissipation whereas the numerical example in Section II 

 accounts for the partition of the remaining energy among reflected, 

 transmitted and internally dissipated energy. Subtracting the energy 

 dissipated on the rough slope (the external energy dissipation) from 

 that of the incident wave assumed in Table 4 shows that the remaining 

 energy may be regarded as the energy associated with an equivalent 

 incident wave of amplitude aj = Ra^. With a^ = 0.069 foot, as specified 

 in Table 4, and R = 0.84, from equation (145), the amplitude of the 

 equivalent incident wave is a^ = 0.84 (0.069) = 0.058 foot. This is seen 

 to be the incident wave amplitude assumed in the numerical example in 

 Section II, Table 1. The two numerical examples are therefore closely 

 related and illustrate the details of the calculations involved in the 

 procedure for the prediction of reflection and transmission coefficients 

 of trapezoidal breakwaters, which is discussed in Section IV. 



79 



