258 



fied with a particular type of measurement. A summary description of the 

 pertinent WRL equipment concludes this chapter. 



Experiment Apparatus 



Instrument description 



Two-dimensional wave channel. The two-dimensional wave channel 

 provides a constant channel width of 12 ft (3.66 m) over a length of 342 ft 

 (104.2 m). The test section is 15 ft (4.57 m) deep with 3.5 ft (1.1 m) of 

 freeboard extending above the ground line. The wave generator is hinged at 

 the bottom, 18 ft (5.49 m) from the south end of the channel, in an overall 

 depth of 18 ft (5.49 m). The increased depth at the wave board provides a 

 greater immersed surface area for increased wave generation capacity. The 

 18-ft (5.49-m) depth continues for 4 ft (1.22 m) in front of the wave board 

 and then shoals to a depth of 15 ft (4.57 m) over a horizontal distance of 40 ft 

 (12.2 m). The 15-ft (4.57-m) depth continues for 250 ft (76.2 m) and then 

 rises vertically to a depth of 3 ft (0.91 m). The 3-ft (0.91-m) depth continues 

 for the last 30 ft (9. 1 m) of the wave channel. Plan and elevation views of 

 the channel appear in Figure 13-2. 



For SUPERTANK, a trapezoidal-shaped concrete sill was cast in place in 

 front of the wave board to prevent transported sand from accreting near the 

 wave board hinges and seals. The sill was 1 ft (0.3 m) wide at the crest, 

 1.7 ft (0.5 m) high, and had slopes at 50 deg (0.87 rad), fore and aft, as 

 shown in Figure 13-3. The near edge of the sill was 4 ft (1.2 m) from the 

 base of the wave board. Threaded inserts into the top of the sill allowed it to 

 be removed with a hoist. 



One-inch (2.54-cm), coarse threaded, stainless steel insert pairs were cast 

 into the walls and floor of the wave channel, spaced at 12-ft (3.66-m) incre- 

 ments on center, horizontally. Insert pairs are separated by 8 in. (20.3 cm) 

 horizontally, repeating at 1-ft (0.30-m) centers vertically on both interior wall 

 surfaces of the channel. Insert pairs were also placed in the bottom of the 

 channel, starting 2 ft (0.61 m) from the wall and continuing at 4-ft (1.22-m) 

 spacings across the channel. The threaded inserts allow instrumentation and 

 models to be attached to the walls and floor of the channel. 



The inserts also serve as stations for the SUPERTANK project. The first 

 row of inserts, at the beach end of the channel, occurs 1 ft (0.30-m) from the 

 vertical face separating the 15-ft (4.57-m) and 3-ft (0.91-m) channel depths. 

 This is referred to as Station 1 . Station numbers increase by one for each 

 column of inserts, separated by 12 ft (3.66 m) of longitudinal distance. The 

 extreme station is station number 22, which is (22-1)12 + 1 = 253 ft 

 (77.1 m) from the beach end of the 15-ft- (4.57-m-) deep section of the wave 

 channel. Inserts are identified in Figure 13-2. 



Chapter 13 Wave Generation and Data Collection Systems 



