Table 4. Stagnation regime and Froude number based 

 on obstacle thickness in photo sequences. 



Figure 



Pile 



Stagnation Regime U^/gt 



12 

 14 



15 

 16 



3-inch circular 

 Pile with 25 fins 

 6- inch circular 

 5x1 H-pile C6 = 0°) 



Smooth runup 

 Smooth runup 

 Jetting runup 

 Smooth runup 



5x1 H-pile (.6 = ^0°) Breaking runup 



0.6 

 0.6 

 1.2 

 7.2 

 1.4 



of V+, but the bluntness and surface complexity of the obstacle clearly 

 have some effects on the stagnation regime. This can be seen by compar- 

 ing Figures 15 (k) and 16(e), where the stagnation regime goes from smooth 

 to breaking runup as F^ decreases, opposite the expected trend. 



The photos indicate that wave flow does not directly penetrate the 

 pile's channels at certain orientations. The water level in the channel 

 is horizontal and responds to the sloping exterior flow around the pile. 

 This is clearly shown in Figure 18; the sloping exterior flow causes a 

 "stairstep" variation in water level within the channels around the pile. 



Figure 18. "Stairstep" runup in channels around a pile with 25 fins. 

 Crest incident from upper right of frame. 



37 



