and moved by hand, and the surface smoothed to conform to the desired 1:10 

 slope. The water level was then raised above the disturbed portion of the 

 coal surface. The bottom was then vibrated throughout the disturbed portion 

 by means of a heavy submersible penetrating mechanical vibrator. The water 

 level was then lowered, the volume of material needed to offset compaction 

 was added, and the surface resmoothed. Usually, only about a 1-inch layer 

 of coal was lost to compaction, so that the vibration was done only once. 

 Once the slope was remolded, the water level was set at the desired depth, 

 and the adjusted wave generator was started. The system was then allowed 

 to run to approximate equilibrium as defined by a lack of change on the 

 survey profiles to a point approximately 10 feet seaward of the proposed 

 starting location of the device. A suitable equilibrium state was normally 

 attained after about 40 hours of wave action. The flume was then judged 

 to be ready to receive the device again. 



7. Device Placement 



The device was then placed in the flume with its flaps opening in 

 a landward direction. Four cables, bifurcated and attached to the top and 

 bottom of the vertical flap valve supports, were fastened to the overhead 

 cable by turnbuckles and U-clamps. The fastening cable was sufficiently 

 loose to allow the device to float at its normal level, yet sufficiently 

 tight to keep the device from moving either landward or seaward. The flume 

 walls restrained lateral movement of the device without interfering with 

 its vertical oscillations. 



8. Device Operation 



With the device in place, the generator and height-recording 

 apparatus were started. Wave action was allowed to continue for about 20 

 minutes (one hour and 17 minutes in the prototype) for static and mobile 

 tests. At the end of the selected time, for a static test, wave action was 

 stopped. For a mobile test, at the end of the initial period of wave action, 

 the device would be rapidly winched landward, usually about 0.2 feet (equiv- 

 alent to about 3.0 feet in the prototype). After the same length of time, 

 the landward winching process would be repeated. Wave action would not be 

 stopped during the entire mobile test. 



9. Run Termination and Analysis 



At the end of a run, wave action would be stopped, the device 

 removed from the flume, and the coal surface in the flume surveyed. The 

 results of this survey would be graphed as an overlay and compared with the 

 pre-run survey. This compari6on clearly illustrated the areas of accretion 

 and erosion in the vicinity of the device. A quantitative analysis of 

 accretion and erosion, on both sides of the device, was made by planimeter- 

 ing the graphed areas of concern. The results of these analyses from the 

 basis of the conclusions on the feasibility of the device for moving sand. 



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