Table 5. Runup calculations for [W(a)/W] 



patterns in Figures 21, 22, and 25. 



Data set 



Wave 

 period, 

 T 

 (s) 



Water 



depth, 



d/Lo 



Wave 

 height , 

 H 

 (ft) 



Crest 



height, 



W 



(ft) 



Measured 

 runup , 

 [W(a = 0°)/W]-l 



Calculated 

 runup, 

 [u2/2gWl 



Fig. 21 



(A) 



2". 32 



0.036 



0.08 



0.048 



0.02 



(0.02)1 



Fig. 21 



(•) 



2.32 



0.036 



0.18 



0.11 



0.13 



(0.04) 



Fig. 21 



(•) 



2.32 



0.036 



0.41 



0.26 



0.43 



0.26 



Fig. 22 



(I) 



1.55 



0.081 



0.34 



0.167 



0.40 



0.23 



Fig. 22 



(A) 



2.32 



0.036 



0.34 



0.223 



0.27 



0.19 



Fig. 22 



(■) 



3.10 



0.020 



0.34 



0.256 



0.24 



0.17 



Fig. 23 



(A) 



3.55 



0.036 



0.49 



0.275 



0.21 



0.10 



Fig. 23 



(■) 



3.55 



0.036 



0.68 



0.40 



0.36 



0.16 



Fig. 23 



(•) 



3.55 



0.036 



0.85 



0.51 



0.46 



0.23 



^Value in parentheses calculated from linear wave theory. 



simply related to U; increasing [W(a = 0°)/W] indicates increasing U. 

 Figure 21 shows the W(a) minimums moving slightly toward a = 180° with 

 increasing U, while Figure 22 shows the minimums moving slightly away 

 from a = 180° with increasing U. Figure 23 shows no well-defined trend 

 with U in the minimum locations. Despite the confusing behavior. of the 

 minimums, the peak water level near a = 180° is approximately equal to the 

 incident crest height for the data in Figures 21, 22, and 23. 



Petryk (1969) reported the separation points on a surface-piercing 

 circular pile in steady unidirectional flow move toward the rear of the 

 pile as (u2/2ga) increases, until the wake_becomes aerated. In all the 

 present tests, the minimums in W(a) or W(a) lie within ±35° of 

 \a\ = 125°, but show no regular excursion with U (Figs. 21, 22, and 23). 

 This suggests the minimums do not always indicate the flow separation 

 points, because the peak water records can be affected by secondary flow, 

 such as splashes, in the pile's wake. This is_ clearly indicated in 

 Figure 23, where multiple minimioms occur in W(a) for the highest wave 

 condition. 



Flow separation at a body and wake processes are influenced by the 

 Reynolds number, R = Ul/v, where £ is a characteristic flow length and 

 V is kinematic fluid viscosity. The Reynolds number measures the ratio 

 of inertial to viscous forces. The present tests were designed to show 

 prototype stagnation effects, determined by the Froude number, F = U^/gZ. 

 Since this Froude number is identical in both laboratory and prototype 



44 



