Polar plots with measured wave dimension as radial coordinate and 

 orientation angle as azimuth are presented in Figure 6; the average 

 measured wave height, crest height, and trough depth are shown for four 

 test piles with the same incident wave condition. For each pile, the 

 variation in wave height with angle is replicated in crest height, while 

 trough depth shows less variation. CThe circular pile data in Fig. 6, a 

 show an effect of electrical gage drift discussed in App. A.] 



The pattern and bilateral symmetry of wave transformation about the 

 tank centerline direction are emphasized by the polar format in Figure 6. 

 The nonlinearity of wave transformation is emphasized by a data display 

 in which measured peak water level is divided by average incident crest 

 height. Figure 7 shows that two normalized data sets do not superpose, 

 although the test situation is identical in both cases, except for inci- 

 dent crest height. 



Figure 8 illustrates data smoothed by averaging the points symmetri- 

 cally located about the tank centerline, i.e., WC6) and WC360°-B)_j_ , 

 since_ these test situations should be equivalent. This results in WCo) 

 or WCS) data, and removes some data variability caused by electrical 

 gage drift, temporal wave variability, and irregular flow around sharp 

 edges and in wakes. The slight increase in peak water away from B = 0° 

 seems more visible in Figure 8(b) than in Figure 6(c). 



Appendix C is a comprehensive data presentation of computer plots 

 in a rectilinear format with normalized peak water level versus orienta- 

 tion angle. The format of individual figures in this report has been 

 chosen to accomplish the purpose of the data display. 



II. PHOTOS OF HIGH WAVES AT PILES 



The principal data reported are peak water measurements at a point 

 near various surface-piercing piles in wave flow (see Sec. III). This 

 section presents several sequences of frame enlargements from 16-milli- 

 meter motion pictures of high waves at piles. Figure 9 indicates the 

 camera and pile configurations for the photo sequences. These photos 

 provide a qualitative record of wave flow effects indicated by the water 

 surface near the pile, and furnish a framework for several general con- 

 clusions about the flows investigated. 



1. Circular Pile . 



The two photos in Figure 10 are rear views of a circular pile as a 

 wave crest arrives. Test conditions are: 2a = 0.125 foot (3.8 centi- 

 meters) , d = 1.00 foot (30.5 centimeters), T = 2.32 seconds, H = 6.41 

 foot (12.5 centimeters), W = 0.27 foot (8.2 centimeters), 32 frames per 

 second film speed. In Figure 10(a), the crest is approaching the pile. 

 The bow wave around the pile's front is particularly visible at the 

 upper right of the frame, and the spilling flow at the pile's sides is 

 noticeable. The flow separates from the pile near a = tl30**, judging 

 from the breaks in water surface slope. Water flows up the back of the 



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