u.sS. Army Sra pee U.S. Army Coastal Engineering Research Center A FEASIBILITY STUDY OF A WAVE-POWERED DEVICE FOR MOVING SAND MISCELLANEOUS PAPER NO. 3-67 JUNE, 1967 Marine Biological Laboratory yi (45) AUG 1 4 1967 450 WOODS HOLE, MASS. We ie nao —bF DEPARTMENT OF THE ARMY | CORPS OF ENGINEERS OON30 Material contained herein is public property and not subject to copyright. Reprint or re-publication of any of this material shall give appropriate credit to U. S. Army Coastal Engineering Research Center. Limited free distribution of this publication within the United States is made by the U. S. Army Coastal En- gineering Research Center, 5201 Little Falls Road, N.W., Washington, D. C. 20016. When this report is no longer needed, please return it to the originator. MBL/WHOI AAA 0 0301 0089733 4 JUNE, 1967 MISCELLANEOUS PAPER NO. 3-67 A FEASIBILITY STUDY OF A WAVE-POWERED DEVICE FOR MOVING SAND by Frederick F. Monroe U.S. ARMY COASTAL ENGINEERING RESEARCH CENTER ABSTRACT A model of a wave-powered, sand-moving device, suggested by the staff of the U. S. Rubber Company Research Center, was tested for ifs feasibility as a dredging device early in 1965 at the U. S. Army Coastal Engineering Research Center. Sixteen tests were made under various wave conditions at a 1:15 scale reduction. Waves with prototype periods of 5, 7, 9, and |5 seconds were tested. Wave heights varied from |.| to 4.4 prototype feet in) prototype Of fshome! depirhs Of 3857, 34°55) and S30 een.) in halt omy tine 16 runs, more sediment was accreted landward of the dredge than was eroded and deposited seaward of it, yet, in only two of these tests was the shore- ward accretion significant. On the other hand, of the eight tests that resulted in erosion on the shoreward side of the device, five showed sig- nificant amounts. Accretion landward occurred when the dredge was operated in shallow water over a nearly horizontal bottom. Over a sloping bottom, the dredge served generally to erode material and deposit it downslope. These results indicate That the device, at least in its present form, is unsuitable for use in moving sand shoreward from offshore sources, and that further testing in the prototype is not justified. Despite the dis- appointing results, the operation of the device illustrates the possibility of a great potential for The utilization of wave power. FOREWORD Artificial beaches have proven to be so successful and economical as a means of shore protection that in some localities there is now a scarcity of onshore sources of hydraulic fill. Presently seismic explorations are seeking offshore sources of sand that could be recovered by ocean-going hopper dredges. A device, such as the one tested here, could prove in- valuable in moving sand to The turbulent zone from the limit of deep-draft dredge operation. Frederick F. Monroe, an Oceanographer in the Research Division, con- ducted the tests and prepared the report under the genera! supervision of Thorndike Saville, Jr., Chief of the Research Division. During the time of the tests, Colonel F. O. Diercks was Director of the Center, and at the present time, J. M. Caldwell is both Acting Director and Technical Director. NOTE: Comments on this publication are invited. Discussion will be published in the next issue of the CERC Bulletin. This report is published under authority of Public Law 166, 79th Congress, approved July 31, 1945, as supplemented by Public Law 172, 88th Congress, approved November 7, 1963. CONTENTS Page SSCs © C ENERABMre chi ey moulded Rel onc iiel cu mleWittel gedmeware: Popecewilevahey ch Uist haw on ice de | lo Imrrecwerion oo 4 RGMeR. isp chime eit oho): kiya molak crue: grollee era ver. Oey live 2. Description of Bewies 0 6 nid Now Onur Ol Oyo ® ONO NG move 3. Operation of Sand-Moving Device Aion od Ol Ouchy aiaoy Vo oan oun 3 Ssserion Will, WESIESEIUIP on vehtol sore: tele ho Bd Lol al cg nolan, yal tom Guliah culos auns 5 lo Ihe Wave TaRK oo oo 6 0 6 6 Oooo 6 OO 6 Oo Oo 5) 2o INOSOROGP SACI 66 oo 646 6 6 5 6 00 6 8 Oo 0.0 0 0 8 HO 6 3o Sail Similan Proril@ oo 6 os do 6 6 8 6 606 0 0 6 06 6 4, Sand Simulant Characteristics . 6 5. System for Moving Device 0 6 6. Establishment of Equilibrium PORTIS. 8 Seeing MME SIP ROCEDU RES ciue Us WatielMsiuoi tel sres) p/eomrellifeh cep te) ies)iateh ey ptey (ark 8 lo Iesr Iyoes 8 2. Water Level 03 SIV COMION iat UCT > DMO IOS etts CNecabn a naeee deo ouec 9 3. Wave Height Measurement? 00 SUI terion Nou Mteuitsthied De umremints 9 4, Wave Height and Period Calibration. g) 5. Profile Surveying Technique . 9 6. Slope Remolding . : DRS blesih acraieetcn aioe kos cbs 6 1G 9 fa Device Placemeiir so 05-9 0 6h 000 0 Oo 6.6 016.6 0-6 6 5 10 8, Device Ooerariom 6 so CHUAN Lostod HC INGTON Gu linte cp Rate, 10 9. Run Termination and ARIES. SLAs WMvoy Jule hietbir cu) fact i glrotidonpare) Affe) Massy Pa Hee 10 I@. Seale RelerioMmsiipS ¢:o%o.0 6 6 66 6 0 6106 6 6 6 6 I | Seerion IW (RESUILTIS oo 56 040.0 06.00 006 6 616 00°95 0 0.6 6 4.0 | General Deseriprion OT Figures © wWhiroligiN Zl o 56 6°96 6 06 6 || ie 2, Generel Descripirion OF Valoles |] ahold So o'6.06 60 0 0 |2 5, Discussion and Resulrs oF Rums | winrougi) I 6 oo 6 6 696 6 14 4, ComelUSIONS o 05 6 6 0 0,026 46106 0.0 0 0606.00.00 00 25 | LLUSTRAT | ONS Figure a View of Device, Check Valves in Open Position -b View of Device, Check Valves in Closed Position View of Test- enum é 6 a Cross Section of Absorber Beach | Bronte. b Cross Section of Test Flume Profile -a Winch for Moving Device : b Shoreward Section of Cable Syston NNUWMFN ND ILLUSTRATIONS (Cont. ) Figure 5 Molded Slope vs sage Frorile ror [Firsir Wave Condition... 000000000000 6 Profile after Run | vs Equilibrium Profile for First Wave Condition... Sako omic “be OMS eOntonMouaa 7 Profile Run 2 vs Profile Run lo 9 § Prorile Rum 5 VS Prorile Rum 2 o 9 Profile Run 4 vs Profile Run 3 . : 10 Profile Run 5 vs Profile Run 4 . I | Profile Run 6 vs Profile Run 5 . c [2 Profile Run 7 vs Profile Run 6 . 15 Profile Run 8 vs Profile Run 7 . 0 0 °c 14 Profile Run 9 vs Profile Run 8 ID Prorile nun 10 vs Proriie Ruin 9 16 Profile Run II vs Profile Run 10 . I” lProrlie Rum |2 vs Profile Rum Il o.oo oc a 0 18 Profile Run 13 vs Equilibrium Profile for Third Wave Condition 0 19 Profile Run 14 vs Profile Run 13. . . 20 Profile Run 15 vs Equilibrium Profile, Fourth Wave Condition 0 2| Profile Run 16 vs Profile Run 15 . Table | Basic Run Characteristics 0 2 Wave Conditions and Water Dente 0 9 3 Reduction in Wave Height Caused by Device de WE Tes) [oreehi oll. aso Geo uicl culo. loeto Osbe ol ou GuG9 5 oo)-o8-G 1646 5 Device SrriM] oo6o000%0 0 0 9 0 009000000000 6 Effect of Device Operation, Landward Side 600 6000 0 7 @Effect of Device Operation, Seaward Side . 8 Net Effect of Device Operation . Page A FEASIBILITY STUDY OF A WAVE-POWERED DEVICE FOR MOVING SAND by Frederick F. Monroe Research Division, Coastal Engineering Research Center | GENERAL alin dtcisiion A model of a wave-powered sand-moving device, suggested by the staff of the U. S. Rubber Company Research Center, was tested for its feasibility as a device for moving sand toward shore, at the U. S. Army Coastal Engineering Research Center, Washington, D. C. from | Jaunary 1964 to 15 March 1965. The purpose of the series of tests was to determine whether the model operated sufficiently well to justify further testing in the prototype or at very large scale. It had been suggested that a successful prototype would provide an economical means of moving sand from offshore through water too shallow for standard floating dredge operation to the beach area itself, or to within reach of a beach-based, permanently placed suction line, or dragline. The possibility existed that such a device could be useful in the general program of proposed beach improvement around the shores of the United States and other areas, particularly if offshore sand deposits, presently being sought, proved to be of sufficient size and quality to warrant their being used as borrow areas for beach replenishment. 1|f practicable, nearshore sources could provide sand for beach nourishment or possibilities might exist that an ocean-going dredge could unload within the reach of the wave-powered sand-moving device which would then transfer the sand to the surf zone. Although the use of devices such as modified amphibious military craft have been proposed for this purpose, the develop- ment of an economically operated and soundly engineered machine has remained elusively beyond the reach of existing technology. An additional benefit to be derived from the use of a wave-powered sand-moving device is that it would use naturally available energy to move considerable sand quantities to shore, except for the winching and emplacement phases of operation. Ds Description of Device The model wave-powered sand-moving device used in this study was shipped to the Coastal Engineering Research Center on 28 October 1964 by the U. S. Rubber Company, which had done considerable preliminary development and testing. The initial development of the device is covered in a report by Rhodes.* This model, as received, consisted of two flotation pads composed of synthetic closed-cel|! rubberoid foam, located fore and aft, and attached ¥Rhodes, 1. J., Memorandum on Wave-Dredging Systems, United States Rubber Company Research Center, Wayne, New Jersey, March 4, 1963. Figure I-a View of Device Showing Check Valves in Open Position Figure |-b View of Divice Showing Check Valves in Closed Position by two laterally located horizontal beams. The waterline of the device, in fresh water, lay along the center of these rigid beams. Suspended out- side these beams and pivoting on the connecting rod to them, was a pair of rigid vertical members, between which were held four fiberglass flaps acting as check valves, with lead sheathing on their lower edges to speed their closing (see Figure |-a). With this configuration, the device could be operated only in a constant water depth sufficient to utilize all 4 flaps. The configuration was modified by narrowing the flap valves and placing their supporting vertical beams inside the horizontal beams that connected the flotation pads. In this way, the apparatus could be either raised or lowered by moving the rod from a particular flap valve and replacing it through a lower, or higher, valve as desired. Hence the dredge could be operative and in various water depths (in shallower water than before its modification). 3. Operation of Sand-Moving Device Theoretically, the sequence of operation of the sand-moving device is as follows. The device was initially floated over the shoreface seaward of the breakers. Then a wave crest passed, causing the submerged valves to open landward (Figure |-a), allowing the orbital current to pass through them unobstructed, except for the energy required to open the valves. With the passage of the subsequent trough, a seaward directed current is generated. This current closes the valves and creates a very powerful current downward and seaward, under the device (see Figure I-b). This current causes con- siderable scour beneath the device if it is located a relatively short dis- tance above the surface of the bottom. This scouring action places large amounts of sediment in suspension on the seaward side of the device. The presumption then was that with the passage of the next wave crest, the suspended sediment would be flushed through the opened valves and deposited on the landward side. Thus material is removed from under the dredge, placed in suspension to seaward, and carried shoreward and deposited by the shore- ward component of the orbital current. By moving the device slowly shoreward, the mound of deposited material ahead of it would be progressively transported inshore. Il TEST SEP |. The Wave Tank The test series took place in a wave tank which measures 85 feet in length, !4 feet in width, and 4 feet in depth, and has a series of trans- parent glass panels, spaced about 10 feet apart along one side, and an eccentrically driven pusher-blade type of wave generator at one end. This tank was modified somewhat for the testing of the wave-powered sand-moving device. The modification consisted of the construction of a narrow flume along a portion of the windowed tank wall. The narrow flume was necessary to fit the size of The model device so that the waves would not act around it, and to minimize the needed amount of the sand simulant which was fine coal. In addition, the narrowness of the flume allowed the remainder of the shoreward end of the tank to be used as an absorber beach to eliminate Figure 2 View of Flume and Absorber Beach Setup (taken after testing) _-s— End Wall LOS ale aa abs? SSS ae | on 10 slope Gravel = Armor Lancer Tank Bottom Figure 3-a Cross Section of Absorber Beach Profile ego a ! on 10 slope -——-— Water Level —- 2 : SILLLALT ELT L MLD gS fe, 2) 2 Tank Bottom Concrete Separator Layer (1 "thick minimum ) Figure 3-b Cross Section of Test Flume Profile 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 |.5 feet from the windowed wa!l 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 shim was fastened to the splitter wall delineating the initial profile 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 I!-inch layer of concrete. A |.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 |.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 wal | Figure 4-a Winch for Moving Device Figure 4-b Shoreward Section of Cable System and the tank side wall at the generator end of the flume. A 3/8-inch diameter cable was wound several times around the winch and passed through a sheave that was connected to a turnbuckle which was, in turn, attached to the shoreward wall, and made continuous by fastening the ends together with U=-clamps (see Figures 4-a and 4-b). This system allowed the device to be moved back and forth about half the length of the flume, limited only by the inability of the U-clamps to pass either through the sheave or around the winch. The device was then connected to the overhead winching cables by smaller cables attached to the vertical flap valve supporting members on each side of the device above and below the flotation pads. This configuration allowed the device to be moved by the wave action in a dominantly vertical direction unhindered, but restricted to a very smal! amount of its horizontal motion, back and forth in the flume in the direction of wave motion; the flume walls, of course, eliminated any lateral motion. 6. Establishment of Equilibrium Profile Before testing for each wave condition, the slope was brought to an equilibrium profile using the waves to be tested. First, the water level, measured near the generator blade over the concrete tank bottom well away from the flume, was set at 2.0 feet using a stationary point gage. The model period for the waves to be generated was established using the vari-drive of the eccentrically driven pusher-blade type wave generator. The desired wave height was then established by trial and error by setting the eccentric arms that controlled the amount of horizontal movement of the generator blade. The generator was then started, and the resultant wave heights were measured with a two-wire resistance type wave gage located in 2.0 feet of water just outside the mouth of the flume. By this process, the desired wave height was obtained and waves were allowed to impinge on the coal slope until it was estimated the near-equilibrium had been established over that section of the profile on which the device was to operate. The equilibrium profile for the initial wave condition tested was always established by about 40 hours (about 155 prototype hours) of wave action. Whether or not a profile had reached equilibrium was determined by periodic soundings every 0.5 feet along the flume. The soundings were then reduced to a datum and plotted graphical ly against the profile from the preceding survey. Figure 5 on page 34 shows the equilibrium profile for the initial wave condition for Run | compared with the molded slope before any wave action. Il) WEST PRCOEDURIE |. Test Types The actual testing procedure began after the equilibrium profile was established. Two basic types of tests were conducted. In the first type, a static test, the device remained at a single location in the flume for The duration of the test. In the second type, a mobile test, the device was moved a prescribed distance by a winch and cable after a certain amount of wave action, usually more than one hour in the prototype (about 20 minutes in the model). 2. Water Level Throughout the test program, the water level gage remained at the same location, and prior to each run, the water in the tank was measured and established at the desired level. 3. Wave Height Measurement A resistance type stainless steel dual-wire probe was suspended in the water in the estimated center of the flume at approximately the location proposed for the device for the ensuing test run. This probe was fastened tova flat carriage that spanned the width of the tank, and could roll from one end of the tank to the other over level rails on top of the concrete sidewalls. The wave-height sensing probe, once in position, was linked to a 2-channel pen-motor recorder. The wave gage recorder system was balanced and calibrated before and after each run of short or moderate duration, and periodically during long runs. Also, the sensing probe was adjusted to record linearly. 4. Wave Height and Wave Period Calibration The eccentric arms of the wave generator control the length of the blade movement which determines the height of the wave. The period of the generator is, of course, the period of the wave and can be checked by stop- watch. Approximately 3 minutes of wave action were allowed prior to recording the waves for height analysis to allow tank effects to reach an equilibrium state with respect to the waves being generated at that Time. After the 3 minutes, wave heights were analyzed immediately, and the eccen- tric setting of the generator arms was altered until the desired wave height was obtained. Then all wave action was stopped and the surface of the coal in the flume was surveyed and its profile drawn. 5. Profile Surveying Technique Two technicians surveyed the flume bottom profile. A technician on the carriage sounded the depth of the coal surface with a modified Philadelphia rod attached to the carriage and fitted with a foot to prevent its penetration into the coal. A measuring tape, 40 feet long, was attached to the inside wall of the flume where it could be easily read by another technician who also pushed the carriage to the desired location and noted the depth reading and its location on a data sheet. 6. Slope Remo | ding After a series of runs involving the use of the device, the bottom was sometimes deeply entrenched and uneven. If this was the case, it was felt that variable shoaling and reflection effects might well cause erroneous results, and the coal bed was remolded. The wave conditions for. the run sub- sequent to remolding were set on the generator and the water was drained below the level of that segment of the bed to be remolded. Crushed coal was added 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 |-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 |7 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 comparison 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. 10. Scale Relationships The test series was conducted on a reduced scale of roughly I:15. Representative profiles obtained during the study are shown in Figures 5 through 21; all dimensions are in actual model terms unless otherwise specified. In Tables | through 8, both model and prototype terms are listed where applicable. Prototype terms are computed according to Froude relationships as follows: linear dimensions, such as length, height, width, and depth are obtained by multiplying the actual model dimension by a factor of 15: that is, | foot in the model is equivalent to |I5 feet in the proto- type. Volume dimensions, such as the amount of sediment moved by the device, are computed by multiplying the actual model volume by a factor of IDeeor 3375; for example, 0.2 cubic feet in the model is equivalent to 675 cubic feet in the prototype. Time dimensions are computed by multiplying the actual time in the model by a factor of the square root of 15, 3.873, so | hour of actual running time in the model is equivalent to 3.873 hours, or 3 hours, 52 minutes in the prototype. In the discussion of the indivi- dual test runs, prototype terms will be used throughout unless otherwise spectfied. 1V RESULTS |. General Description of Figures 6 through 2| Figures 6 through 2! show the profiles that existed prior to and after each run, and thus shaw the effect of the device. operation for each run. For contrast, a 4X vertical exaggeration was employed. The tank wal | at the end of the tank opposite the generator is represented by the left side of the graph. The solid |ine represents the profile that existed prior to each run, and is so labeled; the dotted line shows the profile as it existed after each run. The numbers along both the ordinate and abscissa of each graph represent actual (not prototype) distances in the model in feet. The stillwater line is shown for each run and is so labeled. The water depth, measured outside the flume near the wave generator, labeled "offshore water depth", the wave period, and the wave height are listed for each run in both model and prototype terms. The wave height listed is the average of the wave heights recorded during each run as measured by a dual-wire resistance probe located outside the mouth of the flume in roughly the same depth as the offshore water depth. In each of the first seven runs (Figures 6 through 12) the location of the wave gage between the device and the shore is marked and labeled. Each position occupied by the device for any period of time is also marked on each of the graphs showing the effects of device operation. It should be noted that the dotted line (post-run) profiles do not always extend the entire length of the solid line (pre-run) profile. By observing the device in operation for short periods of time, it seemed that the area directly affected extended only about 3 model feet on either side of the device. This observation was severely limited by the shortage of window area in the tank wall. Some profiles were thus taken only to show these direct local effects, and so extended only a portion of the length of other profiles. 2. General Description of Tables | through 8 Tables | through 8 list variously the basic conditions that existed for each run, and some of the changes caused by the presence and operation of the device. Table | lists the test type of each run; that is, whether the deyice remained at a single location throughout a run, a static test; or whether it was moved periodically during the run, a mobile test. The condition of ‘the slope prior to each run is also listed, that is, whether the slope was in approximate equilibrium with the wave condition to be tested, or whether the slope was the result of the preceding run. This listing defines the solid line profile on Figures 6 through 21. The length of time each run lasted is also noted in Table |, in model terms, in minutes and in equiva- lent hours and minutes for prototype derived by reducing the model times to hours and multiplying them by the square root of the scale factor, 3.873, according to Froude redationships. Table 2 lists the offshore water depth, wave periods, and average off- shore wave height that prevailed for each run, in both model and prototype terms. Table 3 lists the changes in the average wave height caused by the presence and operation of the device for Runs | through 7. The offshore wave gage, as noted in Figures 5 through 21, was placed outside the mouth of the flume in 2 feet of water in The model, the equivalent of 30 feet in the prototype (except as specified in Table 2). This measurement was made a distance offshore from the end wall of the wave tank of 43 feet in the model, 645 feet in the prototype. The inshore wave gage was located at various places between the device and the intersection of the bottom profile with the stillwater line. Due to the changing profiles, this gage was ope- rated in various water depths and located as shown on the comparative pro- files for the first seven individual runs (Figures 6 through 12). The use of this gage was terminated after Run 7 due to calibration problems. The inshore gage was located an average distance of 10.4 feet in the model, or 156 feet in the prototype, from the end wall of the tank. Another column in Table 3 lists, for the applicable runs, the percentage of average wave height reduction inshore of the device caused by its presence and operation. Table 4 lists the location of the device at the beginning and end of each run relative to the end wall of the wave tank in both model and proto- type terms. An additional column lists the distance the device was moved in mobile tests, again in both model and prototype terms. Table 5 defines the device setting for each run, that is, the depth Cin feet) of the deepest part of the device below the stillwater surface in both model and prototype terms, and the number of flap valves operating. The depth of the deepest part of the device is the distance from the water- line on the device, down to the lower edge of the lowest flap yalye. The number of flap valves operating during a run was equal to the number of valves extending below the axial supporting rod through the uppermost act- ing valve, the vertical valve supports, and the horizontal flotation pad support beams. The inactive valves were attached to the vertical valve supports as were the active valves, but were suspended aboye the flotation pads and thus out of reach of impinging waves. Table 6 lists the effect of the presence and operation of the device on its landward side. Table 7 lists, similarly, the effect on its seaward side. In the case of a static run, the landward side of the device was de- fined as that portion of the pre- and post-run profiles extending from the station over which the device was located, proceeding toward the inter- section of the bottom profiles with the stillwater line as far as the device was believed to have caused changes. The seaward side, also in the case of a static run, was similarly defined, But in the opposite direction. [n the case of a mobile run, both the seaward and landward effects were defined beginning immediately under the final rather than the initial position of the device. These tables |ist the computed volume of sediment in both mode! and prototype terms, either accreted, that is, where the post=run profile had a higher elevation above the bottom than the pre-run profile, or eroded, where the post-run profile had a lower elevation that the pre- run profile. These volumes were derived, in model terms, by planimetering the two-dimensional area of the comparable profiles, and multiplying this value by the width of the flume. The prototype volume was then obtained by multiplying the model volume by the cube of the scale factor, 15°, oF 3375, with both model and prototype values given in cubic feet. Table 8 lists the net effect of the presence and operation of the device in two columns headed "Landward" and "Seaward", in both model and prototype terms. These two columns show results of the summation of Tables 6 and 7, respectively. For example, Table 6 lists the amount of accretion of sediment on the landward side of the device after Run | as 0.007 cubic feet in model terms. Also, the amount of eroded sediment on the landward side is listed as 0.003 cubic feet. Therefore, by subtraction, the net resultant is accretion of 0.004 cubic feet on the landward side. Like pro- cedures were followed to obtain the remainder of Table 8. The real sig- nificance of this table is, however, somewhat uncertain. As has already been stated, the profile surveys made after each run covered only that portion of the bottom that was suspected of having been affected by the presence and operation of the device. The distance covered, therefore, was extremely variable; for example, after Run |, a distance of 2 (mode |) feet was covered on.the landward side, with 3 feet being included in the post-run profile on the seaward side. In contrast, however, a very notice- able bar was formed inshore of the device during Run 7, so the surveyed profile was expanded to cover 2.6 model feet landward and 5.5 feet seaward of its final position. The uncertain significance of Table 8 lies in the origin of the resultant accreted sediment, and in the deposition of the eroded sediment. In addition to the variable survey coverage, other possible sources of the discrepancies between the net landward and net seaward quantities of accreted and eroded sediment, which should theoretically balance, can only be qualitatively explained. One explanation is the loss of suspended sediment, seaward of the device, out into the main part of the wave tank. This loss most certainly occurred to some extent as coal was noted in the form of small ripples over the entire tank bottom after the tank had been drained. Some of the sediment in several runs was contributed by the shoreward erosion of the bottom profile. Some sediment was probably moved to the measured bottom profile by the migration of the ripples into the flume from the main wave tank. In addition, some sediment may have been moved by the device from the seaward to the landward side and vice versa. Other possible contributing causes for the existing net discrepancies may be error in measuring, plotting and in planimetering the comparative prot! 16S. lt is likely that some combination of each of these various possibilities did occur. Nevertheless, a run resulting in a net accretion on the landward side of the device should be viewed as successful, although, with waves of extremely long period, such as in Runs 14 through 16, the natural tendency is to build the beach. The contribution of sediment move- ment by the device therefore remains somewhat indefinite, even though com- pared To generally near-equilibrium conditions. Experience indicates that for the waves of low steepness, more sediment would have accreted landward of the position of the device had the device not been present. However, in the case of impinging, shorter period (high steepness) waves, accretion landward should be viewed as significant. 3. Discussion and Results of Runs | through 16 a. Run |. Figure 5 onpage 34 illustrates the differences between the molded slope and the profile as it had evolved in approximate equilibrium with the prescribed wave conditions at least sufficiently far seaward to cover the location at which the device was to be placed. The nearshore concavity and offshore convexity of the equilibrium profile are normal for waves of such a short period as 5 (prototype) seconds. The equilibrium profile thus established, the device was placed about 237 feet offshore from the intersection of the stillwater line with the equilibrium profile, in water having a depth of about 18.75 feet (see Figure 6). The device was set at its deepest setting so that its lowest flap valve was touching the bottom. At this setting 4 flap valves were operat- ing and the topmost rod was connected to the vertical valve supports through the top hole set, one hole above the uppermost valve. On the landward side of the device most of the 10 cubic feet of sediment that was eroded was de- rived from the immediate vicinity of the device, while the accretion on the landward side was composed of a rather thin, uneven layer of sediment, having a volume of about 24 cubic feet, covering an area landward of the device location for a distance of about 40 feet. The trough dug by the device, which accounted for most of the erosion landward of the location of the device, continued even more deeply to seaward and accounted for the erosion of 35 cubic feet that took place on that side of the device. Seaward and downslope from the trough, 49 cubic feet of sediment accreted tn a rather thick layer extending about 36 feet seaward of the downslope trough limit, about 48 feet from the device. Run | lasted about 50 minutes so the sedi- ment movement took place at a rather rapid rate. Waves having an average height of 1.8 feet in 30 feet of water impinged on the device and were reduced in height 22 percent to |.4 feet by its presence and operation. The resultant energy released was used primarily to operate the device and to move sediment. The device, located in front of a window in the sidewall of the tank, could be observed in operation. However, after the first few waves, the water was filled with suspended sediment which severely limited visibility and photography. The activity that took place very close to the window could be seen and gave the impression that the sediment in suspension was primarily present in two vortexes, one on either side of the device, with the seaward one being considerably larger in extent. These vortexes rotated rapidly, but at different rates, directions, and at different times, the main impetus being provided by the trough-generated current that flowed in a seaward directim beneath the device. This current caused the larger, seaward vortex to spin in a counterclockwise vertical direction at a rapid rate when the trough was passing. This spin direction seemed to continue at a decelerating rate for some time after the trough had passed and the passage of the subsequent crest had begun, then accelerated again with the oncoming trough. Most of the seaward deposition seemed to take place as the vortex was slowing down, beginning farther seaward and progressing toward the device. As the crest passed, some sediment was seen to flow through the opened flap valves but, relative to the whole seaward vortex, the amount seemed to be quite small. Similarly, a smaller vortex was observed on the landward side of the device. This vortex seemed to spin rapidly in a clockwise direction when the trough was passing, but reversed direction with the passage of the wave crest and spun counterclockwise quite slowly until the subsequent trough arrived. The sediment on the landward side of the device was deposited during the short periods of time when the spin reversal was taking place, which may account for the thinness and unevenness of the accreted layer. The narrowness of the window in the tank wall prevented observation of the full scope of the activity within the flume, and observation from above was prohibited by the density of -the black suspended material. The net effect of the presence and operation of the device was to produce an equal net accretion of 14 cubic feet over the surveyed areas of both sides of the device. Due to the limitations of the post-run survey, if is not known where the accreted material came from, but a net accretion on the landward side of the device was at least initially promising though of such smal | amount as to possibly be within the error of measurement. b. Run 2. For Run 2, the device was moved landward some 4.0 feet from its location during Run | (see Figure 7). The profile over which the device was to operate was the same as existed at the end of Run |. For this run, the wave period was the same as for the preceding run, 5 seconds, but the average wave height in 30 feet of water was lowered to |.5 feet. The average wave height was decreased by the device only 7 percent, to |.4 feet, during this run. Run 2, like Run |, was a static test and lasted 50 minutes. The setting, too, was the same, with 4 flap valves operating; the edge of the deepest was about 20 feet below the stillwater surface and in contact with the bottom at the start of the run. On the landward side of the device, thin layers of sediment, totaling 22 cubic feet and 21 cubic feet accreted and eroded, respectively. In Run 2, most of the erosion that took place in the trench dug by the device, both seaward and landward of its location. The heaviest deposition took place on both sides just beyond the periphery of the trench, with the main portion of landward deposition occurring within about 32 feet of the trough rim. Most of the seaward deposition was occupied with filling the trench dug during Run |, while some erosion took place sea- ward of the trench in some of the accreted material that had been deposited during Run |. On the seaward side, 19 cubic feet of sediment eroded and 25 cubic feet accreted, hence the device produced a net accretion of 6 cubic feet on that side. This result is indicative of the increased hydraulic activity that took place on the seaward side of the device although sti|| within the limits of measurement accuracy. c. Run 3. The device was located about 32 feet farther landward for Run 3 than for Run 2, and quite close to The base of a rather steep off- shore slope in the bottom profile (see Figure 8). As the device was To be operated in shallower water than the preceding two runs, its flap valves were raised one setting so that the rod connecting the flap valve rack to the vertical supports was passed through the uppermost flap valve, causing the lower edge of the deepest valve to extend about |15 feet below the stillwater line, just in contact with the coal bed that existed after the completion of Run 2. Four flap valves operated during the run, however. Run 3, like the two preceding runs, was static, with the device staying in the same location for the 50-minute duration of the run. The wave conditions were the same as during Run 2, with a period of 5 seconds, and an average offshore wave height of |.5 feet in 30 feet of water. The device reduced The wave height quite significantly by 47 percent during the run, cutting the average height from |.5 to 0.8 feet. This was perhaps a consequence of proximity of The device to the steep offshore slope. The effect of the slope was very noticeable with regard to the volume and location of the sediment transplanted by the device. On the landward side of the device, no accretion occurred, but 4 cubic feet eroded. Again the erosion took place primarily in the trench dug by the device on both the landward and seaward sides. A very slight amount of erosion occurred for a short distance immediately landward of the trough. On the seaward side of the device, 27 cubic feet of material eroded, and 48 cubic feet accreted. As before, most of the erosion took place in the trench, the accretion occurring as a sizable mound decreasing in thickness seaward, beginning at the seaward rim of the trench and tapering in thickness downslope after continuing to fill the trenches made during Runs | and 2. The net effect 16 of the presence and operation of the device was net erosion of 4 cubic feet from the landward side of the device, and a net accretion of 22 cubic feet on the seaward side. This net transfer of sediment seaward is probably an indication of the effect of the steeper slope a short distance landward of where the device was operating. That sediment which was flushed landward probably slid down the slope into the trench and thence was transported to the seaward side. d. Run 4. For this run, the device was moved about |7 feet far- ther inshore than it had been for Run 3 (see Figure 9). The wave period remained at 5 seconds, and the offshore water depth at 30 feet, but The offshore average wave height was increased slightly to |.6 feet. In order to accommodate the lesser water depth, the rod connecting the flap valve rack to the vertical supports was passed through the second flap valve from the top, thus placing the uppermost flap valve almost totally above the waterline of the device, and completely removing it from effective dredging operation. With this configuration of three operative valves, the lower edge of the bottom flap valve extended to a depth of about 14 feet beneath the stillwater surface. Like the preceding three runs, Run 4 was a static test, and of the same 50-minute duration. The dredge setting and/or location had a profound effect on the wave height as the average offshore impinging wave height was 1.6 feet, while the average wave height measured at a gage inshore from The device was only 0.7 feet, a reduction of 56 percent. After Run 4, the entire profile was surveyed to see what changes had occurred over its length during the preceding portion of the test series. This survey showed that a rather small amount of headward erosion of the shore had occurred above the still- water line, in addition to the movement and slight enlargement of some of the small nearshore bars (see Figure 9). In the vicinity of the device, Run 4 produced the usual trench and increased the steepness of the slope immediately landward of the device. The depth of the trench was less than in previous runs; the width was about the same. Some accretion also took place on the rim of the steep slope landward of the device. Offshore, there was a small amount of filling in the trench left by Run 3, but some erosion of the seaward rim. Still farther seaward, a small amount of accretion took place. In that portion of the profile landward of the device, about 123 cubic feet of material accreted, while some 189 cubic feet eroded. Seaward of the device, the profile was surveyed some 83 feet. Downslope from the trench, 62 cubic feet had eroded, while 27 cubic feet had accreted. The presence and operation of the device during this run produced a net erosion of 66 cubic feet on its landward side and a net erosion of 35 cubic feet on its seaward side. Presumably, accretion occurred seaward, outside the surveyed area. e. Run 5. Run 5 comprised the first mobile run of the test series, that is, the device was moved a specified distance landward periodical ly without any cessation of wave action (see Figure 10). The pre-run profile was that which existed at the end of Run 4. The initial location of the device was inshore of that of the preceding run by only about 4 feet, so that it remained at the same setting with three valves operating. Run 5 was of 7 hours and 43 minutes duration in all and the device was moved 3 feet landward about every hour and 10 minutes, for a total landward movement of 15 feet. The wave period was 5 seconds and the average wave height offshore in 30 feet of water was 1.5 feet. The device, over the entire run, reduced this wave height only 27 percent to |.1| feet. As this run was the first of its type in the series, a survey of the whole bottom profile was made after the run. Only a smal! amount of headward erosion of the shoreline occurred, with, as in Run 4, some movement and enlargement of the nearshore bars. In the vicinity of the device, however, some rather spectacular changes occurred. Evidently, the usual trench was dug beneath the device, but only that segment of the trench which was dug in the final position is shown in Figure 10, with the rest having been backfilled. The landward progression of the device eroded the steep slope, noted in the discussions of the two preceding runs, and placed only a smal! mound of accreted material on its landward side. This landward erosion amounted to 218 cubic feet, while the amount accreted was only 134 cubic feet, a net loss of some 84 cubic feet of sediment. Seaward of the device, however, only 89 cubic feet of material eroded, all from the steep slope, i.e., that portion of it that became the trench as the device was moved. Seaward of the rim of the final position trench, all of the material, about 248 cubic feet, accreted. This material took the form of a long, deep, flattopped mound, extending from the final position trench of Run 5 to over the land- ward rim of the trench created during Run 3. Offshore of this mound was a dip reflecting the filling of the Run 3 trench, and a subsequent mound reflecting the seaward rim of this now-buried trench. Beyond this point, the mound of accreted material tapered down rather sharply to the pre-run profile. In all, only 89 cubic feet of sediment eroded, while some 248 cubic feet accreted on the seaward side of the device, a net gain seaward Of ISS cubic fee; From the results of Runs 4 and 5, it was concluded that the device, when backed by a rather steep slope, contributed sediment some distance offshore; much of it to points seaward of the device. It is likely that the steepness of the slope landward of the device was too great for any accretion to take place on if. f. Run 6. For Run 6, the device was located about |18 feet land- ward from The apex of the mound accreted at the inshore rim of the steep slope during Run 5 (see Figure |!1). Due to the shallow depth of the water at this location, the device was set at its highest setting, that is, the rod connecting the flap valve rack to the vertical supports was passed through the lowermost flap valve, making only one valve operable, the re- maining three being suspended above the waterline. At this setting, the lowest edge of the flap extended about 5 feet beneath the stillwater surface. This run was static, the device remaining at the same location for the hour and |7-minute duration of the run. The waves had a period of 5 seconds and an average height of |.4 feet in 30 feet of water. The presence of the device again served to reduce the average wave height inshore of the device, but produced only a 14 percent lower wave, with an average height of |.2 feet. The device dug the usual trench but during this run, probably due to both the shallow water depth and the length of Time the device was operated at one location, the trench was wider and deeper than those noted 18 during preceding runs. The mound which accreted during Run 5 on the land- ward rim of the steep slope and some of the upper portion of that slope eroded away. Most of the sediment derived from this erosion filled the trench dug at the base of the slope at the final device position of Run 5. During Run 6, the profile inshore of the’ device had a gentle slope and sub- sequently was more receptive and retentive of the sediment placed in sus-. pension and deposited by the device. The largest mound of accreted material was deposited just landward of the inshore rim of the device-dug trench, with smaller assemblies of accreted sediment farther landward. In all, on the landward-side of the device within the distance covered by the survey, 62 cubic feet of material accreted and 46 cubic feet eroded, resulting in a net inshore gain of 16 cubic feet. Seaward of the device location, how- ever, 58 cubic feet of sediment eroded, while 25 cubic feet accreted in the distance surveyed, giving a net loss of 33 cubic feet. The accretion of such a volume of material on the landward side of the device tends to support the hypothesis that the device operates more effect- ively on a gentle slope than on a steep slope. g. Run 7. Run 7 served as a mobile test of the device in shal low -water, over a more moderate slope. As in Run 6, only one flap valve was operable. The initial location was 9 feet inshore of the position during Run 6, and it was operated in waves having a 5-second period, but only a |.l-foot average height in 30 feet of water. Due to the mound of accretion that developed during the run, the inshore wave gage had to be moved to various locations as noted on Figure 12. The average inshore wave height, computed from the various gage measurements, was reduced by the presence and operation of the device, about 46 percent to 0.6 feet. As a small amount of sediment had been accreted on the landward side of the device during Run 6, one of the main purposes of Run 7 was to attempt to move the mound farther inshore, and, if possible, enlarge it in the process. For The duration of this run, the device was moved shoreward 3 feet approxi- mately every hour and 56 minutes, for a total running time of 25 hours and 10 minutes, and a total distance of 36 feet. The results of this run were most interesting. About 14 feet landward of the final device location, beginning at the inshore rim of the device- dug trench, was a large mound of accreted sediment which attained a maximum elevation of 0./5 feet above the stillwater line. This mound of accreted material terminated about 40 feet inshore from its point of origin. This occurrence resulted in the creation of an offshore bar with a back bay inshore of it. The beach area profile, however, changed almost negligibly. The trench beneath the device was deeper and wider than any previously noted. The trench created during Run 6 was filled for the most part by the accretion of material placed during Run 7, but no other accretion occurred within the surveyed area seaward of any of the device locations. Landward of the final location, 218 cubic feet of material accreted and only 35 cubic feet eroded; the net accretion of 183 cubic feet was in the * form of the inshore bar. Seaward of the final location, 38 cubic feet of sediment had accreted and 319 cubic feet had eroded, a net erosion of 281 CUDIC eek. One noticeable difference in the behavior of the device during this run versus its previous behavior was that the flotation pads rose and fel| vertically with considerable force. This flapping created what appeared to be a possible pumping effect caused by the rapid passage of wave crests. This phenomenon may or may not have had an effect on the creation of the large mound of accreted material inshore from the device. h. Run 8. The main purpose of Run 8 was to attempt to move the large mound that accreted inshore of the device during Run 7, still farther inshore, and up on the beach. As many be seen in Figure 13, this did not happen. For Run 8, the wave period remained at 5 seconds, but the average offshore wave height in 30 feet of water was increased from |.| feet to |.5 feet. The device remained at its same setting, with one flap operating, for the entire run. The run was of the mobile type, and the device was placed 3 feet seaward of its final position at the end of Run 7. The device was moved 3 feet every hour and 56 minutes, without stopping wave action, for a total running time of 38 hours and 44 minutes, covering a total dis- tance of about 57 feet. The most noticeable effect of This run was The total erosion of the large mound accreted in the previous run. This ma- terial not only filled the trench made during Run 7, but caused a consider- able amount of sediment to be accreted on the surface of the shelf near the seaward edge of the device, but also down the steep offshore slope and beyond. A small trench was dug during Run 8 at the location beneath the final device position, and a small amount of accretion was noted adjacent to the device on its landward side. Due to the proximity of the device to the shoreline, as well as calibration difficulties, the inshore wave gage was not used during this run, nor for the remainder of the test series. No measure of wave height reduction by the device was thus obtained. Figure 10 shows the amount of accretion landward of the final position of the device to be small; planimetric analysis showing that 30 cubic feet of material were accreted, and 25 cubic. feet were eroded, a net accretion of 5 cubic feet. Seaward of the final location, however, some 483 cubic feet accreted within the limits of the survey, while 472 cubic feet eroded, a net gain of || cubic feet (the net value being within the errors of measurement). The pumping effect of the flotation pads of the device, as noted in the discussion of Run 7, was not observed during Run 8, which may account for the very limited amount of accretion that took place landward of the device. This run destroyed all the good effects observed in the previous run and showed essentially that a mound of material, accreted in shallow water, landward of the device, could not be moved inshore to the stil lwater line by the device in its present form for at least some common wave and slope conditions. i. Run 9. For Run 9, the device was returned to deeper water and set so that three of its flap valves would be operable. The profile re- mained as it was at the end of Run 8, which resembled the equilibrium profile shown in Figure 5. The offshore water depth remained at 30 feet, but the wave period was increased to 9 seconds, and the average offshore wave height 20 to three feet. Run 9 was a static run in order to observe the single- station behavior of the device under this new set of wave conditions. The run was about one hour and |I7 minutes in duration. As may be noted in Figure 14, the device was located about one-third of the way down the final offshore slope. This slope, prior to Run 9, continued down to the tank bottom rather evenly with but a small level step about one-third of the way up from the bottom. The lower edge of the deepest flap extended to a depth of about 14 feet below the stillwater line. A trench of con- siderable width and depth was dug during Run 9, and caused the accretion of a rather sizable mound landward up the slope. Seaward of the trench, the device caused the accretion of two smaller layers of sediment, one immediately seaward of the trench rim, and the other immediately seaward of the previously mentioned level step in the slope. These two areas of accretion were separated by a smal! area of erosion when the level step in the slope had been. Landward of the device location, about 132 cubic feet accreted, (al in the mound) and 82 cubic feet eroded (all in the trench) for a net gain of 50 cubic feet. Seaward of the device, an erosion of 149 cubic feet occurred, mostly from the trench but with some from the downslope step, while the two areas of accretion seaward amounted to about 154 cubic feet, a net accretion of 5 cubic feet. The extra accretional material was most probably contributed both from offshore and headward erosion not surveyed. The results of this run indicated that the device might be somewhat effective in waves of longer period. Jj. Run 10. The purpose of Run 10 was primarily to attempt to move the mound of material accreted landward of the device during Run 9 farther inshore. As may be noted in Figure 15, this did not happen. Run 10 was of the mobile type, with the device being moved approximately every hour and |7 minutes for a total distance of 5 feet with the device at two locations and a total running time of 2 hours and 35 minutes. At its final location, the flap valve rack was tilted 30° with the lowest flap nearer the shore. This was done to attempt to force the sediment, placed in sus- pension by the under-device current generated by the passage of the wave trough, to remain closer to the seaward side and so make more suspended sediment available to be flushed through the open valves with the passage of the subsequent crest. As the device would be working in shallower water than it was in Run 9, it was set so that two valves would be operating. At this setting, the lowest edge of the deepest flap would extend about 9.5 feet beneath the stillwater line with the device in a vertical attitude. For this run, the waves had the same 9-second period as in Run 9, but their offshore height was decreased a smal! amount to average 2.7 feet in 30 feet of water. The device*caused a very smal! mound of accretion (see Figure 15) rather high up on the level portion of the profile above the slope. Seaward of this small mound, the device eroded a considerable amount of ma- terial down the slope to the wide, but rather shallow, trench dug during Run 10. This erosion created a gentler seaward slope, but removed all of the material accreted landward of the device during Run 9, plus more material up the slope. Seaward of the device location during Run 10, a large mound of accretion more than filled the large trench created during Run 9. 2l Landward of the device final location, about || cubic feet of material accreted, while 258 cubic feet eroded, producing a net loss of 247 cubic feet. Seaward of the final position, about 228 cubic feet of material accreted, while only 6 eroded, producing a net accretion of 222 cubic feet. lt appeared rather clearly in this run that the sediment eroded from the landward side of the device was deposited on its seaward side. Tilting the flap rack shoreward also seems to have produced negative results. k. Run ||. For Run ||, the device was relocated on the level shelf inshore of its position during Run 10 (see Figure 16). Since it was to operate in shallow water, the device was reset so that only one flap was operable. It was to be operated while in a vertical attitude so the lowest edge of the flap extended about 5 feet below the stillwater surface. It was hoped that a mound of accretion, similar to that created inshore of the device during Run 7, would be repeated, and perhaps be even larger, considering the 9-second wave period with an offshore average wave height of 3.4 feet that was to be used during Run I|. This run was of The static type, with the device remaining on station for about one hour and |7 minutes of wave action. As shown in Figure 16, no mound was accreted landward of the device, but a very wide and deep trench was dug beneath its position. Seaward of the rim of this trench was a rather thick layer of accreted material covering the slope. At the downslope terminus of the accreted, material, a small pocket of erosion occurred. While no sediment was accreted inshore of the device, 126 cubic feet eroded, all from the landward portion of the trench. Seaward, however, 253 cubic feet eroded, mostly from the trench, but 375 cubic feet accreted, producing a net seaward gain of 122 GUDIC reENo Run |1 tended to reinforce the idea that the flotation pad pumping effect, noted in Run 7, was significant in the accretion of the large mound inshore of the device, and that without that effect, with the device moving normally as in Run ||, no landward accretion would be realized. |. Run 12. For this run, the device was moved only a short dis- +ance inshore from its position during Run ||, so that a significant amount of material would be accreted to landward. As may be noted in Figure I7, this did not happen. Run 12, again, was of the static type and lasted for one hour and |7 minutes, as did Run I|. The wave period for this run was 9 seconds as before, but the average offshore wave height was increased to 3.6 feet in 30 feet of water. As the device was to be located just over the inshore slope of the trench dug during the preceding run, it was set so that two flaps would be operative, the edge of the lowest one extending about 9.5 feet below the stillwater line with the device in a vertical attitude. This run caused a smal! mound of accretion, about 19 cubic feet in volume, to be created with its apex about 52 feet inshore of the device location. The device eroded a trench almost as deep as that dug during Run ||, but of considerable width on its inshore slope. The creation of this broad but rather gentle inshore slope, beginning at the seaward | imit of the accreted mound and extending to the point of maximum trench depth, succeeded in eliminating most of the level area inshore of the device location noted in the two previous runs. 22 As may be seen in Figure 17, much of the 228 cubic feet eroded from inshore of the device during Run 12 was accreted seaward, partially filling the trench dug during Run ||, and spilling down the slope into deeper water. The erosion of several steps of the slope was noted, alternating with rather thin layers of accretion, with the result that 152 cubic feet eroded seaward of the device, while 486 cubic feet accreted, a net seaward accretion of 334 cubic feet, versus a net landward erosion of 209 cubic feet. Even with the rather long wave period, the device was unable to create a sizable mound of accretion landward of its position. It is also worth noting that the pre- viously mentioned pumping effect of the flotation pads was not noted in Run 12. m. Run 13. After Run 12, the wave period was changed to 7 seconds. The post-Run 12 profile indicated that an equilibrium profile was needed for the third wave condition of the test series. Accordingly, a 1:15 molded slope was made in the flume and waves having an average wave height of 4.4 feet in 38.7 feet of water, and a 7-second period were allowed to impinge on it for approximately 154 hours at the end of which time near equilibrium was reached. This equilibrium profile is shown in Figure 18. Since Run 13 required a new set of wave conditions, the test was to be a static one, with the device being set so that 3 flaps were operative, the lowest of these extending to a depth of about 14 feet below the stillwater line. Run 13 was of about || minutes duration, but of profound effect on the profile. The change in the equilibrium profile was so great that it was almost certainly caused by the presence of the device in operation, although the trench dug during Run 13 was neither especially wide, nor deep. As may be seen in Figure 18, a small mound of accreted material (about |7 cubic feet) was present inshore from the trench rim after Run 13. In this case, the inshore terminus of this mound has been considered the landward limit of the direct effect of the device operation. A rather long seaward accretion layer was noted extending from the offshore trench rim about 66 feet seaward to The shelf break. In the region near the stillwater line, a considerable amount of headward erosion occurred, causing a rather large amount of sediment to be deposited seaward in a layer of tapering thickness terminating on the shelf a short distance landward of the smal! accretion mound inshore of the device. On the landward side of the device, 5/2 cubic feet accreted, 587 cubic feet eroded. On the seaward side, 61 cubic feet eroded, and 10! cubic feet accreted. Thus a net loss of material attributable to the operation amounting to 15 cubic féet accrued on the landward:side of the device and a net gain of 40 éubic feet was registered on the seaward side. n, Run 14. For Run 14, the offshore water depth was lowered to 34.5 feet, but the average wave height of 4.4 feet and period of 7 seconds remained, as in Run 13. For this mobile run, the initial position of the device was identical with that in Run 13. With the exception of the second position, the device was moved 3 feet every || minutes. The 22-minute stay at the second position produced no noticeable effect on the final profile, which was taken after about 2 hours and 20 minutes of running time, when 23 the device had operated over a distance of about 30 feet. As in Run 13, the device had a vertical attitude with 3 flaps operating, the lowest one extended about 14 feet below the stillwater line. The decrease in the water depth lowered the maximum elevation of wave attack on the shorel ine and greatly decreased the amount of headward erosion that occurred during this run. However, some erosion did take place, providing sediment which created an offshore bar and a rather thick layer seaward down the shelf. The device dug a deep, wide trench and deposited mounds of material near both the inshore and offshore rims. Landward of the device, 499 cubic feet accreted, and 397 cubic feet eroded; on the seaward side, 476 cubic feet eroded, and only 375 cubic feet accreted. A net accretion of about 100 cubic feet resulted on the landward side and a net erosion of the same amount resulted seaward. This run termi- nated the testing under this particular set of wave conditions. o. Run 15. The purpose of Runs 15 and 16 was to observe the operation of the device in waves of low height and long period. Such wave conditions naturally tend to cause the accretion of material on beaches. Accordingly, the offshore water depth was set at 30 feet, the wave period at 15 seconds, and the average offshore wave height at 2.8 feet. A 1:15 molded slope was subjected to these waves for approximately 154 hours until a new equilibrium profile was obtained as shown in Figure 20. The device was then set in the vertical position so that 3 flaps operated, the lowest about 14 feet below the stillwater line. As a mobile run was required, the device was moved 3 feet approximately every hour during a total test time of about 5 hours and 49 minutes, a total distance of |15 feet. The rather long wave used in attaining an equilibrium profile, created a broad, essen- tially bimodal, offshore bar over which the device operated during Run 15. The device was positioned between the peaks and, as usual, dug a trench beneath it, the deepest portion thereof being near its final station. A group of small mounds accreted on top of the inshore lobe of the bar, land- ward of the trench rim. Similarly, a single mound accreted atop the more offshore peak on the bar seaward of the trench. Farther offshore, this accreted sediment tapered down the slope in a thin filet. Landward of the device, 49 cubic feet accreted, and only 35 cubic feet eroded, leaving a net gain of 14 cubic feet. Seaward of the device, much more activity was noted with the accretion of 124 cubic feet and the erosion of 94 cubic feet. The amount of sediment accreted landward of the device was considered too small to attempt to move it toward the shore, so the device was moved inshore of the bar for the next run. p. Run 16. The water depth remained at 30 feet for Run 16, the offshore wave height at 2.8 feet, and the period at I5 seconds. As in Run 15, the device remained set with 3 operating flaps extending to |4 feet below the stillwater line. This mobile run lasted 19 hours and 22 minutes, with the device being moved 3 feet about every hour, for a total distance of 5/7 feet. Several small low mounds accreted slightly above and below the stil l- water shoreline (see Figure 21). The device eroded away the inner bar and some of the slope, which probably supplied not only the small amount of 24 sediment for the shoreline area accretion, but considerably more sediment for accretion seaward of the device, which began on the offshore side of the trench and continued seaward, filling the trench created during Run |5, then tapering down the slope. The peaks of the accretion mounds remaining after Run 15 were slightly eroded, also supplying some sediment. Planimetering the compared profiles from this run and Run 15 shows that 58 cubic feet accreted on the landward side of the device, 187 cubic feet eroded, a net erosion of 129 cubic feet. Seaward of the device, 355 cubic feet accreted and 205 cubic feet eroded, a net accretion of 150 cubic feet. The rather small amount of accretion that occurred landward of the device during this run would appear to demonstrate an unsuccessful dredging device, especially in light of the beach-building wave characteristics employed during this run. 4. Conclusions The results and analyses indicate that the device, in its present form, is unsuitable for moving sand shoreward from offshore sources. Table 8 shows that the results are not entirely consistent. For example, during Run 7, the novel behavior of the flotation pads acting in conjunction with the flap valves appeared to produce a pumping effect that may wel! have caused the resultant mound of accreted material. This mound was not moved shoreward during Run 8 in spite of the similarity of the impinging wave conditions. Run 14 is the only other run in which significant landward accretion occurred, but the effect of the beach-building wave used for the run is not known. The small positive net gain from Run 15, and the negative result from Run 16, cast doubt on the usefulness of the device, even under beach-building wave conditions. The offshore wave height was reduced 46 percent by the presence and operation of the device during Run 16. This decrease represents a usage and reflection of about 70 percent of the off- shore impinging wave energy, yet the energy was obviously used to move sediment offshore rather than onshore. Such variegated results are more than likely byproducts of the scale effects present in the test. For example, the device was tested over a coal profile over slopes averaging about | on 18, while in nature, shore- face slopes steeper than | on 60 are quite uncommon. Another area in need of more understanding is that of the water mass transport profile, that is, the onshore=offshore velocity distribution over the shoreface. A compre- hensive understanding of this phenomenon and its relationship with the presence and operation of the device would probably cast considerable light on the results. The operation of the device, however, serves to illustrate the possi- bility of a great potential for the utilization of wave power. It appears That if the sediment placed in suspension with the passage of the wave trough could be directed so as to remain within the region of the landward motion of the next wave crest, and if this landward current could be directed to place the sediment far enough inshore to be beyond the reach of the trough- generated seaward current, a similar device might prove successful. 25 TABLE | Basic Run Characteristics Slope Condition Duration Run Test Type Before Run Model Prototype | Static EquITtoriun Prorile® IS mins © hirSo 50 tiline 2 Static Run | 13 min. O Ars. 50 min. 3 Siren lie Run 2 IS iMifdo © IirSo BO illite 4 Static Run 3 13 min. O hrs. 50 min. 5) Mobile Run 4 120 min. 7 hrs. 43 min. 6 Static Run 5 20 min. I IiPo IY mite 7 Mobile Run 6 390 mito ZS IirSo 10 mime 8 Mobile Run 7 600 min. 38 hrs. 44 min. 9 Stat ic Run 8 20 min. l ro IF mit. 10 Mobile Run 9 40 min. ZA WrS>o 5D mime || Stat ic Run 10 20 min. I ho 8 8IY Mh |2 Static Run || 20 min | iro IY mimo 13 Static Equilibrium Profile Stilo © IrSo Il Mime 14 ‘Mobile Run 13 36 tilio 2 lrSe 19 mln 5 Mobile Equilibrium Profile 90 min. 5 hrs. 49 min. 16 Mobile Run |5 300 mina ID InrS. 22 Mite 26 TABLE 2 Wave Conditions and Water Depths Average Wave Period Offshore Water Depth Offshore Wave Height Run Mode | Prototype Mode| (Prototype Model Prototype | 1.29] sec. 5 sec. Zo OO Fro BO5O Faro DoIZ Fro LoS Tro 2 1.291 sec. 5 sec. ASO rs BOO We O10 Fro lod Fro 3 |.29| sec. 5 sec. 2500 ro BOcO ro Q5)0 wire lo® Vite 4 1.291 sec. 5 sec. 200 Tro BOM OM statge Molt ro lo iro 5 1.291 sec. 5 sec. 2500 aFro SOMO tatre Oo1@ WFP. IoD Tc 6 1.29] sec. 5 sec. 2. OO tro SOO Mitatee ORO OM tatz. lott Faro 7 1.291 sec. 5 sec ZOO Fro 5050 Fro O07 Fir lol Po 8 1.291 sec. 5 sec. 2.00 Tio ° S00 ve O10 wr. les Dastitine 9 2.324 sec. Y S860 2500 Fro SOOM fire O20 ro 35O To 10 2.324 sec. 9 sec. 2500 Fro B60 Tre 0.18 ft. Zoll %1o I | 2.324 sec. 9 sec. 2,00 fro SOMOmatue OZ To 3.4 ft. 12 2.324 sec. 9 sec. Zo Fro SOO tre 0.24 ft. 3 To 13 1.169 sec. 7 sec. Zo33 Vo 9 Bol, wo O52 ro 4.4 ft. 14 1.169 sec. 7 sec. Zo) F Po Aro matalne O29) Faro 4.4 fT. 15 XZ, GIS SEC |B Seec 2.00 Fro SOM OM tatrs OoIO Fro 2oS Fo 16 3.873 sec. 15 sec. 2s OO) FAP o BOO) Aro OoI9 Fro 2oS TV o 27 Reduction in Wave Height Caused by Device Average Wave Height Offshore (in’feet)* Run Model —- Prototype | OoIZ Fre |.8 ft. 2 Oo I@ iro IoD Pio 3 Oc IO Fare JoD To 4 Ost wre lo6O Tio 5 Oo IO re [oD Fro 6 WoO!) Fire |.4 fT. 7 O.OY SAro lol to TABLE 3 Average Wave Height (in feet)** Prototype Inshore Mode | O50 Fro O09 Fro O05 wo 0.04 ft. OoO7 Fire 0.08 ft. 0.04 ft. 0.6 (ie fae to ft. faite ike To Wave Height Reduction 22% 1h 47% 56% 27% *For the Offshore Gage, distance offshore from the tank end wall was 43 feet in the model, 645 feet in the prototype. ** For the Inshore Gage, distance offshore from the tank end wall was 10.4 feet in the model, 156 feet in the prototype. 28 TABLE 4 Device Location Original Position* Final Positfron** Distance Moved Run Model ——s Prototype Model ——_—“ Prototype Model _—«sPrototype | 18.00 fT. 2a OW fiaties 18.00 ft. AYO Fars no movement 2 IVoV® Fro AAS) Ro W7odO tre TASS) FN no movement 3) 15.60 ft. DE Ae Tatne 15.60 ft. 234 ft. no movement 4 14.45 ft. ZN Tati 14.45 ft. ANY Fo no movement 5 14.20 ft. AD TP 13520) ifire 198 ft. 1 O.0 Sitatae |S Fro 6 10.60 ft. |D9 FP 10.60 ft. [D9 FAP no movement 7 10.00 ft. 150 wre UO. Frc 114 ft. DMO) EF o 36 Fo 8 ToBO iro IN Ware 4.00 ft. COMifuige HO Po DY tire 9 15950 Fro Eyam valite WDoDO) Pare DIO. GA 0 no movement 10 ISRO OR tate. DDS) Fo 14.70 ft. 22.0 stale O30 Fro D oifalite 1] 9500 are ISD Fro 9.00 ft. ISD Po no movement 12 S550 fir. IZ7 ro BoDO Fro W207 iFifo no movement 13 19550 Tro 292 FV 0 I9oBO arc LGD. FF 0 no movement 14 ORS ORs tates 2) Paatialite W7sDO Tito ASD Fo DOO) Fo 30) Arc 15 IV OO tars ADD Fo 16000 fare 240 ft. o@O wre 1D Wire 16 (2.90) Aro 194 ft. Qol@ wFpro |BO wre HO) rr Di aatales * Feet offshore from tank end wal | **¥ Feet offshore from-tank end wal | 29 TABLE 5 Device Setting Depth of Deepest Part of Device (in feet) Number of Flap Run Model Prototype Valves Operating | 1oDD. Fro IQo9 wre 4 2 [oBS ire IGDoO tre 4 3 OS mitt. 15.4 ft. 4 4 0.92 fT. 13.8 fT. 3 5 WoIZ Fre Jats Faro 3 6 0.34 ft. Doll Wro | 7 0.34 ft. Doll war | 8 0.34 ft. Doll rc | 9 O92 Fro 13.8 fT. 3 10 O65 Fre 9.4 ft. 2 | 0.34 ft. Doll Fro | 12 0.63 ft. 9.4 ft. 2 13 O82 wre 13.4 ft. 5 14 0.92 ft. SDoS Po 3 15 0.92 ft. ISS Fro 5 16 0.92 ft. 13.8 fT. 3 30 TABLE 6 Effect of Device Operation on Landward Side Accretion Erosion (in cubic feet) (in cubic feet) Run Model Prototype Model Prototype | 0.007 24 0.003 10 2 0.007 22 0.006 2| 3 0 0 0.001 4 4 0.036 123 0.056 189 5) 0.040 134 0.065 218 6 0.018 62 0.014 46 7 0.064 218 0.010 BP) 8 0.009 30 0.008 25 9) 0.039 132 0.024 82 10 0.003 I] 0.076 258 I] 0 0 0.038 126 12 0.006 19 0.068 228 13 0.170 572 0.174 587 14 0.148 499 0.118 3Oi7/ 15 0.015 49 0.010 35 16 0.017 58 0.056 187 3| Run Accretion (in cubic feet) Moder 0.014 49 0.008 25 0.014 48 0.008 27 0.074 248 0.008 25 0.011 38 0.143 483 0.046 154 0.068 228 0.111 3715 0.144 486 0.030 10] O.111 BUD 0.037 124 0.105 355 TABLE 7 32 Prototype Erosion (in cubic feet) Model Prototype 0.010 35 0.006 19 0.008 Zi 0.018 62 0.026 89 0.017 58 0.094 319 0.140 472 0.044 149 0.002 6 0.075 DNS 0.045 152 0.018 6l 0.141 476 0.028 94 0.061 205 Effect of Device Operation on Seaward Side TABLE 8 Net Effect of Device Operation Net Accretion (+) or Net Accretion (+) or Erosion (-) Landward of Erosion (-) Seaward of Device (in cubic feet) Device (in cubic feet) Run Model Prototype Model Prototype | +0.004 +14 +0.004 +|4 2 +0.003 rf +0.002 +b G 3 -0.001 -4 +0 .006 +22 4 -0.020 -66 -0.010 55) 5 -0.025 -84 +0.047 +159 6 +0.005 +16 -0.010 =55 7 +0.054 +182 -0.083 -28 | 8 +0.002 +5 +0.003 +] | 9 +0.015 +50 +0 .002 + 5 10 -0.0732 -247 +0. 066 +222 lI -0.038 -125 +0.036 +|22 12 -0.062 -209 +0.099 +334 13 -0.004 =||5 +0.012 +40 14 +0.030 +101 -0.030 -101 15 +0.004 +14 +0.009 +30 16 -0.038 -129 +0.044 +150 33 3.5 n ou y Offshore Water Depth, d= 2.0 feet in the model, 30.0 feef in the prototype. Wave Period, T = 1.29! seconds in the model, 5 seconds in the prototype. Wave Height, H=0.12 feet in the model, 1.8 feet in the prototype. Still Water Line + Offshore wave seaward from end of tank ———————=>— + gage was positioned 43 feet Elevation above Tank Bottom ( ft.) Profile (molded coal slope ) Equilibrium Profile (established after 40 hours of wave action in the model, the equivalent of 154.9 hours in Prior to any Wave Ac the prototype. ) 05) a6) am Tank Bottom —— 3 4 5 6 7 8 9 fo ow Ie i 1) i (6 1 © ww ese eS Oo ee 2 oO tf we HB HK Distance Seaward from End of Tank (ft.) FIGURE 5. MOLDED SLOPE VERSUS EQUILIBRIUM PROFILE FOR FIRST WAVE CONDITION ee ny o Offshore Water Depth, d= 2.0 feet in the model, 30.0 feet in the prototype. ET Wave Period, T = 1.291 seconds in the model, 5 seconds in the prototype. Wave Height, H= 0.12 feet in the model, 1.8 feet in the prototype. iM i=] Still Water rot ry t it Offshore wave seaward from Inshore Wave Gage Position tL gage was positioned 43 feet end of tank ——————> w = t Profile Prior to Run | (same profile as | equilibrium profile, Figure 5) | Elevation above Tank Bottom ( ft.) ° Device Position During Run | 05 Profile After Run | 35 FIGURE 6. PROFILE MADE AFTER RUN | VERSUS EQUILIBRIUM PROFILE FOR FIRST WAVE 3 4 5 6 7 8 9 0 I MB 6 BH G6 Ww GB DW eh gee & & chy oe 2a Distance Seaward from End of Tank (ft.) ‘ea 2O SOMES |e OMn SS eS) CONDITION Ue Offshore Water Depth, d= 2.0 feet in the model , 30.0 feet in the prototype 4 Wave Period, T = 1.291 seconds.in the model, 5 seconds in the prototype. Wave Height, H = 0.10 feet in the model, 1.5 feet in the prototype. Pio ai Wave Gage Position seaward from e nd of tank. _———>— Device Position During Run 2 | | | | Offshore wave gage was positioned 43 feet ° Elevation above Tank Bottom (ft.) os Profile After Profile Prior (same profile if 8 ‘OMI Boi ii i UW BB DW te) A we ee eb ee ae ee @ eo dl & BM Distance Seaward from End of Tank (ft.) FIGURE 7 PROFILE MADE AFTER RUN 2 VERSUS PROFILE MADE AFTER RUN | 34 Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 1.291 seconds in the model, 5 seconds in the prototype. Wave Height, H>0.10 feet in the model, I.5 feet in the prototype. ial i el ad Offshore wave gage was positioned 43 fe Inshore Wave Gage Position seaward from end of tank ——————_=> Still Water Line Elevation above Tank Bottom (ft.) fter Run 3 Profile Prior to Run 3 (same profile as after Run 2) oO i 2 3 4 5 6 7 8 9 io tl Io 1) tS) iS ie TS Deo eee eS Se ee es ee) et) ee Distance Seaward from End of Tank (ft.) FIGURE 8 PROFILE MADE AFTER RUN 3 VERSUS PROFILE MADE AFTER RUN 2 iT | 3.0 Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 1.291 seconds in the model, 5 seconds in the prototype. Wave Height, H = O.II feet in the model, zn = in ri ari ; Tapas aa at a 3 3.5 N wo Offshore wave gage was positioned 43 feet seaward from end of tank. nN i=] uo ° Elevation above Tank Bottom (ft.) (same profile as after Run 3) | Profile 05 ° 12 13 14 15 6 I7 18 19 20 34 Distance Seaward from End of Tank (ft.) FIGURE 9. PROFILE MADE AFTER RUN 4 VERSUS PROFILE MADE AFTER RUN 3 eee 35 | 3.0 Offshore Water Depth, d= 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = |.291 seconds in the model, 5 seconds in the prototype. Wave Height, H = 0.10 feet in the model, 1.5 feet in the prototype. =25 SS | = a = Inshore Wave Gage Position Offshore wave gage was positioned 43 feet 2 Device Positions During Run 5 Seaward) from/endjofitank: B20 b, (device was moved landward a ~ : 02 feet every 20 minutes.) s io Still Water Line ss HAN | | | | s BIS a o Profile Prior to Run 5 s | (same profile as after Run 4) 5 1.0 Se | i [| o5 (Ol L2INESINN4IMISTLGHNNTA T16N TO) 10) “ll lah 13hul4in (Sp ulep ji7iulapISyuzon, 2Ijme2) 123i ayes) N2emulc7mrcsnni2opcs0N 13I) 1S2mnS3mm34 Distance Seaward from End of Tank ( ft.) FIGURE 10. PROFILE MADE AFTER RUN 5 VERSUS PROFILE MADE AFTER RUN 4 35 Go uw Offshore Water Depth, d=2.0 feet in the model, 30.0 feet in the prototype. OC Cee Wave Period, T= 1.291 seconds in the model, 5 seconds in the prototype. Wave Height, H= 0.09 feet in the model, !.4 feet in the prototype. 1 | pale An id me Offshore wave gage was positioned 43 feet Inshore Wave Gage Position seaward from end of tank ————_= | | | | Still Water Line tinea Position During Run 6 ‘ 44 a Profile Prior to Run 6 { N (same profile as after Run 5) Profile After Run 6 Elevation above Tank Bottom ( ft.) Tank Bottom a ra EN ro 8 o uo Gm eo Ss I oie ts Ib (ch Iv ia, nei a ee an et 6G Of ma ee a ea es oh Distance Seaward from End of Tank (ft.) FIGURE ||. PROFILE MADE AFTER RUN 6 VERSUS PROFILE MADE AFTER RUN 5 | LS) a Offshore Water Depth, d= 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 1.291 seconds in the model, 5 seconds in the prototype. Wave Height, H = 0.075 feet in the model, I-I feet in the prototype. i is] Offshore wave gage was positioned 43 feet al Profile After Run 7 u o Elevation above Tank Bottom (ft.) seaward from end of tank. 4 Al Still Water Line Pa PSS Profile Prior to Run 7 \ (same profile as after Run 6) ALS siti Nu Ss s ; : GS ASSSos ‘ 23 ‘ oS of SFE LE Device Positions During Run 7 S> ESE EL (device was moved landward ESF ESES ESE 0.2 feet every 30 minutes.) {tse ite] {lank Bottom a EZ LS NLS NS CHAS SON LINAIS N45 IG NI 7G NI 20 ee 22 e324 e526 272829 SONS S2mS3 NSS Distance Seaward from End of Tank (ft.) FIGURE 12. PROFILE MADE AFTER RUN 7 VERSUS PROFILE MADE AFTER RUN 6 Ny a Offshore Water Depth, d= 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 1.291 seconds in the model, 5 seconds in the prototype. | ny i=} Wave Height, H = O10 feet in the model, 1.5 feet in the prototype. | Offshore wave gage was positioned 43 feet | sdb dissin seaward from end of tank. Profile Prior to Run 8 ZA ‘| al Water Line | iis (same profile as after Run 7) - Viva ch Profile After Run 8 ° Elevation above Tank Bottom (ft.) tia 2a Tere O Device Positions During Run 8 (device was moved landward 0.2 feet every 30 minutes.) ze Tank Bottom A= LL | a ESS Oe a vo oOo om | 506 112 13 14 15 i I7 18 19 20 21 22 23 24 25 26 27 28 2 30 31 32 33 34 Distance Seaward from End of Tank (ft.) FIGURE 13. PROFILE MADE AFTER RUN 8 VERSUS PROFILE MADE AFTER RUN 7 36 3.5 COE 3.0 Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 2.324 seconds in the model, 9 seconds in the prototype. Wave Height, H* 0.2 feet in the model, 3.0 feet in the prototype. ft sag re = Offshore wave gage was positioned 43 feet E seaward from end of tank. —— = 3 Still Water Line 220 = 4 de ~ iia After Run 9 fd : | | B15 eet Tea During Run 9 ) = eat og Ly el 2 ae Prior to Run 9 S (same profile as after Run 8) 21.0 << WwW Ne Le 05 x Tank ari Mae % 2 3 4 5 6 vu 8 BT 0 0S WS se 0D rs) ee) ey eS eh De) EH EES ch) Distance Seaward from End of Tank (ft.) FIGURE 14. PROFILE MADE AFTER RUN 9 VERSUS PROFILE MADE AFTER RUN 8 i | ee 3.0 Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. = Wave Period, T = 2.324 seconds in the model, 9 seconds in the prototype. a Wave Height, H = 0.18 feet in the model, 2.7 feet in the prototype. =25 4 o Offshore wave gage was positioned 43 feet € seaward from end of tank. Ban | Still Water Line < i Profile Prior to Run 10 a (same profile as after Run 9) 3 Baas B15 = i S = ok Profile After Run 10 > a ‘. = 1.0 T 05 = Device Positions During Run 10 (device remained in each position 20 minutes, and sak Bottom was tilted shoreward 30° in the Final position) INS % 2 Ss) 4 5 6 U 8 9 10 i206 0 ob 1 fb @ Db ew ee ee eb ob BS oo oo oe oe Ue US EG Distance Seaward from End of Tank (ft.) FIGURE 15. PROFILE MADE AFTER RUN 10 VERSUS PROFILE MADE AFTER RUN 9 i | | | | 3.0 Offshore Water Depth, d= 2.0 feet in the model , 30.0 feet in the prototype. | Wave Period, T = 2.324 seconds in the model, 9 seconds in the prototype. = Wave Height, H = 0.23 feet in the model, 34 feet in the prototype. p25 a = Offshore wave gage was positioned 43 feet 5 seaward from end of tank. ——————=— S Still Water Line 20 Profile Prior to Run 11 = (same profile as after Run 10) : Neb ‘\ ~ = \ ‘ Shas 8 15 19 Profile After Run I s \ ak E N i=} 51.0 = S 0.5 = a DING 0 A ge ao G Gr 2 0 OND PE MS Gt OR a aa es Distance Seaward from End of Tank (ft.) 24, 25) 26 27 28 29 30 31 32 33 34 FIGURE 16. PROFILE MADE AFTER RUN I! VERSUS PROFILE MADE AFTER RUN 10 37 35 3.0 i a 2.0 Wave Height, H = 0.24 feet in the model, 3.6 feet in the prototyp: Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T = 2.324 seconds in the model, 9 seconds in the prototype. e. Profile Prior to Run 12 (same profile as after Run 1") Elevation above Tank Bottom (ft.) 0.5 Duri Offshore wave gage was posit seaward from end of tank. ioned 43 feet 5 Go vo oo © W@W OU i EF ey Is iS ie I my Distance Seaward from End of Tank FIGURE 17. PROFILE MADE AFTER RUN 12 VERSUS PROFILE MADE AFTER RUN II Offshore Water Depth, d= 2.58 feet in the model, 38.7 feet in the Ls) @ f+ IL Wave Period, T=1.169 seconds in the model, 7 seconds in the prototype. Wave Height, H = 0.29 feet in the model, 4.4 feet in the prototype. QO 72 SB BEY eh es ae el oe (ft.) prototype. 31 32 33 #4 fy o Elevation above Tank Bottom (ft.) Offshore wave gage Positioned 43 feet seaward from end o} kK. Seen After Run 13 Profile Prior to Run 13 (equilibrium profile for third wave condition ) 35 3.0 ny a FIGURE Tank Bottom 5 6 1 8 9 © MW (2 TE i Js uy We IP. Distance Seaward from End of Tank ore Water Depth, d = 2.30 feet in the model, 34.5 feet in the Period, T= 1.169 seconds in the model, 7 seconds in the prototype. Height, H = 0.29 feet in the model, 4.4 feet in the prototype. 21 22 23 24 25 26 27 28 29 30 (ft) 18. PROFILE MADE AFTER RUN I3 VERSUS EQUILIBRIUM PROFILE FOR THIRD WAVE CONDITION prototype. (c) ° Still Water Line seaward from end of tank. wo hee Offshore wave gage was positioned 43 feet a So Device Positions During Run 14 ( device was moved fandward 0.2 feet every 3 minutes, except at Station 19.3 (#) where the device remained for 6 minutes due to -f--~4 a jammed cable.) Elevation above Tank Bottom (ft.) 05 le Aft Profile Prior to Run 14 (same profile as after Run 13) ink Bottom 6 u 8 9 LOPS 2 SA IS Ct 78 9s 20) 2222s e425 6 er co 29 SO Distance Seaward from End of Tank (ft.) FIGURE 19. PROFILE MADE AFTER RUN 14 VERSUS PROFILE MADE AFTER RUN I3 38 31 3 2 33 34 35 3.0 Elevation above Tank Bottom (ft.) Offshore Water Depth, d = 2.0 feet in the model, 30.0 feet in the prototype. Wave Period, T= 3.873 seconds in the model, 15 seconds in the prototype. Wave Height, H = 0.19 feet in the model, 2.8 feet in the prototype. Toe T | till Water Line Device Positions During Run 15 (device wos moved landward IL Offsh seaward f IL jore wave gage was positioned 43 feet rom end of tank ——————— 0.2 feet every 15 minutes ) cae AR Profile After Run 15 05 Profile Prior to Run 15 4 5 Tank Bottom 6 7 8 9 10 I 12 13 14 15 16 17 18 19 20 21 22 23 XK} ey as Br a EO a) ER ERP EY Distance Seaward from End of Tank (ft.) FIGURE 20. PROFILE MADE AFTER RUN I5 VERSUS EQUILIBRIUM PROFILE FOR FOURTH WAVE CONDITION 3.5 ae 3.0 -—+—_}+—} Offshore Water Depth, d= 2.0 feet in the model, 30.0 feet in the prototype. | Wave Period, T = 3.873 seconds in the model, 15 seconds in the prototype. ee Wave Height, H = 0.19 feet in the model, 2.8 feet in the prototype. =25 t ae, Offshore wave gage was positioned 43 feet 5 23 seaward from end of tank. g SS Still Water Line 2.0 x SI Cc =. A) < $ Sh Profile Prior to Run 16 S| 5 ae == bt (same profile as after Run 15) 5 & 3 /| =H 0 { y, Profile After Run 16 ~——+ 05 F a Device Positions During Run 16 (device was moved landward 0.2 feet every 15 minutes ) = : eran Bottom | I on 1 fl ae ° 2 38 @O 8 G P GO Oo DTD eR Be eo er DBP Oa ea 2 es a oD Fa Distance Seaward from End of Tank (ft.) FIGURE 21. PROFILE MADE AFTER RUN I6 VERSUS PROFILE MADE AFTER RUN I5 39 32.33 «(34 *4emod 8AEM $O UO! 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