reflected waves (see Figure 2). To create the flume, a splitter wall, 40 

 feet long and 4 feet high, was constructed of 3/4-inch plywood, and rigidly 

 fastened in the tank, extending from the shoreward wall toward the wave 

 generator, parallel to, and 1.5 feet from the windowed wall of the tank. To 

 prevent seepage of either sediment or water from the flume, a bead of caulk- 

 ing was placed between the base of the splitter wall and the tank floor. 



2. Absorber Beach 



After construction of the wall, an absorber beach, composed of 

 gravel overlain by angular rock about 4 inches in diameter was placed on a 

 1:10 slope in front of a 5-foot level berm between the splitter wall and 

 the tank side opposite the flume. The height of the absorber against the 

 shoreward wall was 3 feet. The absorber beach extended 35 feet toward the 

 wave generator (see Figure 3-a), and 12.5 feet horizontally along the tank 

 width, creating an extensive absorber area. 



3. Sand Simulant Profile 



The sediment profile over which the wave-powered sand-moving device 

 was to be tested was molded in the flume, or obtained as a result of wave 

 action on a previously molded beach. Initially, a lath shorn was fastened to 

 the spl itter wa I I del ineating the initial prof i le to be molded. In order to 

 further minimize the amount of crushed coal needed to simulate to reasonable 

 scale a beach sand which might be encountered in the prototype, a supporting 

 underlayer of sand was first placed in the tank and capped with a 1-inch 

 layer of concrete. A 1.5-foot layer of crushed anthracite coal (the sedi- 

 ment simulant) was then placed atop the supporting underlayer. The coal was 

 shoveled into the flume, vibrated underwater, and molded into a 5-foot level 

 berm, extending toward the generator from the shoreward wall, then sloping 

 with a 1:10 slope to the tank bottom 35 feet from the shoreward wall (see 

 Figure 3-b) . 



4. Sand Simulant Characteristics 



The anthracite coal used in the study has been compared with quartz 

 sand in previous beach deformation studies at the Coastal Engineering Research 

 Center. It had been found that the coal behaved in the model in much the 

 same way as the quartz sand did in the prototype at a scale reduction roughly 

 similar to that used in this study. For that reason it was selected as the 

 bottom sediment material for the wave-powered sand-moving device study. The 

 median diameter of the coal grain was 0.2 millimeters; the average specific 

 gravity was about 1.52 versus 2.65 for quartz sand. The coal grains had been 

 found to have a settling velocity in fresh water of about 4 centimeters per 

 second. 



5. System for Moving Device 



After placement of the coal slope, the system for moving the device 

 was installed in the flume. A hand-operated winch was fastened to a rec- 

 tangle of angle irons that had been attached to the plywood splitter wall 



