The reported tests with circular piles all correspond to the subcriti- 

 cal range, having a larger drag coefficient than intense prototype flows. 

 McNown and Keulegan (1959) stated that increasing wake size is associated 

 with a smaller C^,, so the measured laboratory wakes are generally 

 smaller than prototype wakes. Thus, measured peak water around the rear 

 o£ circular piles is not generally typical of prototypes included in 

 Table 3. 



For the noncircular piles tested, the modeling inaccuracies seem to 

 be of minor importance. The piles have small cross sections, measured as 

 X/L, and Section 111,2 has pointed out that channel shape has a more 

 important effect than pile size on the shape of the W(e) pattern with 

 these thin piles. Also, the Reynolds number is less important in flow 

 past a pile with channels, because the sharp edges establish the points 

 of flow separation. 



3. Conclusions . 



The wave tanks were wide enough that the reported data are free of 

 significant pile confinement effects except for the 3x3 H-pile in the 

 96-foot tank. Because the Reynolds number is lower for the reported 

 laboratory tests, measured peak water around the rear half of circular 

 piles is not typical of prototype situations in Table 3. However, the 

 identical Froude number in model and prototype implies the conclusions 

 concerning wave stagnation effects at various piles (Sec. 111,3) pertain 

 to prototype situations. 



V. COASTAL ENGINEERING APPLICATIONS 



The data in this report (especially App. C) can be used to improve 

 the solutions for the following coastal engineering design problems: 



(a) Determining deck elevations for pile-supported struc- 

 tures in cases where deck elevation is not limited by other 

 design factors. 



(b) Improving the design of decks near pile supports in 

 cases where deck elevation will be subject to wave runup at 

 the pile supports. 



(c) Estimating height to which different types of corro- 

 sion protection is needed on piles and pile-supported 

 structures. 



(d) Clarifying the physical processes causing the wide 

 scatter in measured coefficients used for computing wave forces 

 on piles. For example, it appears that runup can significantly 

 affect wave force on piles in shallow water when 



F^ = ll2/2ga = 1 (Hallermeier, 1976). 



(e) Suggesting novel pile shapes for special design 

 requirements; e.g., capping a thick concrete pile with a narrower 



63 



