The two examples show the Influence of the wave theory used on the value 

 of Cj) determined from a field experiment. Since the determination of wave 

 forces is the inverse problem (i.e., C^j and wave conditions known), it is 

 important in fovoe calculations to use a wave theory that is equivalent to the 

 wave theory used to obtain the value of c^ (and %) • A wave theory that 

 accurately describes the fluid motion should be used in the analysis of 

 experimental data to obtain Cj) (and C^) and in design calculations. 



Results obtained by several investigators for the variation of Cj^ with 

 Reynolds number are indicated in Figure 7-85. The solid line is generally 

 conservative and is recommended for design along with Figures 7-72 and 7-74 

 with the Reynolds number defined by equation (7-45). 



*************** EXAMPLE PROBLEM 26 ************** 



FIND: Were the values of C/j used in the preceding example problems 

 reasonable? 



SOLUTION : For the first example with H = 3.0 m (9.8 ft) , T = 10 s , d = 

 4.5 m (14.8 ft) , and D = 0.3 m (1 ft) , from equation (7-47), 



= 2.3 m (7.5 ft/s) 



(v = 9.29 X 10 ^ m^/s) 



= (2.3) (0.3) ^ ,^,3 ^ ^^5 

 9.29 X 10 



From Figure 7-85, Cj; = 0.7 , which is the value used in the preceding 

 example. 



For the example with H = 3.0 m (9.8 ft) , T = 10 s , d = 30.0 m (98.4 

 ft) , and D = 0.3 m (1 ft) , from equation (7-47) , 



11 (3.0) (1) ,, / /i/-£»./\ 

 "moo: = -(lor (0789) = '*' "^^ ^^'^ '^'^^ 



From equation (7-46), 



R =0^0_(M) = 3.55 X 105 



^ 9.29 X lO"'' 



7-143 



