The peak force per unit pile length at any point along the pile is 

 P = C^ D p ^ 



where, V = peak local velocity, ft/sec 

 Therefore, the total peak wave force on the pile is 



F = f^ pdi = cn P ? r^ v^di 



F = Cd P ^ V2 (3) 



where, V^ = mean square of peak velocity over the pile length 



This peak force occurs when the horizontal components of the water particle 

 velocities reach the peak. This corresponds to a crest or trough at the 

 test section. Assuming the mean peak velocity square does not change as 

 flow reverses direction, the direct wave force on the pile is 



DLc -9 

 Ff =CDfP— V2 



where, Cq£ = drag coefficient at front of pile 



Lc = submerged length of pile at wave crest, ft 



and the reversed wave force is 

 DLt 



■^Dr 



F^ = Cn. P ^^ V^ 



where, Cq = drag coefficient at rear of pile 



Lt = submerged length of pile at wave trough, ft 



The net peak force on the pile is 



AF = Ff F^ = (Cof L^ - C^^ L,) -^ (^) 



Now, if the pile is very long compared to the wave height, the submerged 

 pile length at crest may be considered equal to the length at trough and 

 Equation (4) is reduced to 



AF - (Cjj^ - Cjj^) —2— 



