FIGURE 2. RIPPLE TANK-SCREEN SHOWING EXAMPLE OF 

 WAVE REFRACTION, DIFFRACTION AND REFLECTION 



The eccentricity of the pusher arm on the disc can be continuously 

 varied from to approximately 10 inches using a screw-driven 

 connection. The wave generating mechanism (shown on Figure 3) can 

 produce a continuous range of wave heights from to approximately 

 8 inches, and a continuous rjinge of wave periods from 0.5 to 5.0 

 seconds. A riprap-type wave absorber behind the generating bulk- 

 head has a face slope of 30° with the horizontal and is held in 

 place by 1/2-inch wire mesh. Figure 4 is a general view of the tank 

 taken near the beach (glass) end. 



" Seventy-two-f oof'Tank . - This glass and steel tank is 72 

 feet long, 1-1/2 feet wide, and 2 feet deep. At the opposite end 

 from the generator, glass walls extend 54 feet on one side and 30 

 feet on the other. The wave generator is a replica of that in the 

 "ninety-six-foot' tank and identical wave characteristics can be 

 obtained. The wave absorber behind the generating blade is also 

 of the same design. Level rods on each side of this tank run the 

 entire tank length and permit measurements from a level base. Figure 

 5 is a view along this tank taken from the beach end. 



