bluuebunny/crossref_metadata_2025 huggingface dataset:
TIME AND FREQUENCY LOADING ANALYSIS OF SUBMARINE PIPELINES
Authors: Alexander H.C. , Allen P.L. , Warner J.L.
Published: June 2019

Fatigue damage to marine pipelines subjected to wave forces is evaluated using time-domain and frequency-domain methods. Spectral techniques are applied to North Sea, Gulf of Mexico and offshore Atlantic Canada wave conditions. Time-domain analysis is applied to wave conditions in the Canadian North Atlantic Ocean. The frequency-domain analysis is performed using spectral and probabilistic techniques suggested by L. Borgman {?.). The pipeline dynamic characteristics are described by classical analytical descriptions. The time-domain analysis computes time histories of wave force loading on the submerged pipeline from actual wave records. The traditional Morison wave force equation is used to obtain the time history of the loading on the pipeline. Empirically determined wave spectra are shown not to produce as good a correlation with the deterministic results as the actual wave spectra. Free spanning submarine pipelines subjected to cyclic surface wave loading accumulate strength reductions leading to failure from material fatigue. The Palmgren-Miner rule for the linear accumulation of fatigue damage is applied to evaluate the time to failure. The American Welding Society X-X stress accumulation curve is applied. The results of the deterministic analysis were compared with those of the more efficient spectral analysis. It is shown that comparable results can be obtained from the spectral analysis provided the actual spectra of the water surface elevation is employed in the spectral analysis.
WAVE POWER EXTRACTION AT COASTAL STRUCTURE BY MEANS OF MOVING BODY IN THE CHAMBER
Authors: Kondo Hideo , Watabe Tomiji , Yano Kenji
Published: June 2019

A series of study on wave power extractors which may utilize a part of the coastal structures has been performed by the group of faculties of Muroran Institute of Technology since 1978. Three kinds of extractor belonging to the so-called fixed type had been developed and studied in the laboratory. They are the air chamber with flap, the wave turbine system and the pendulor system. The last two systems have been subsequently studied at the field test plant constructed at Port Muroran. The study shows that the pendulor system brings an excellent power conversion efficiency.
WAVE FORCES AND IMPACTS ON A CIRCULAR AND SQUARE CAISSON
Authors: Van der Meer J.W. , Benassai E.
Published: June 2019

The existing breakwater at Civitavecchia Harbour, Italy, will be extended with a part of caissons. In order to investigate wave forces for this caisson, the Ministero del Lavori Public! commissioned the Delft Hydraulics Laboratory to perform a model investigation on the proposed extension. In the first part of the study quasi-static wave forces on the entire caisson were measured by means of a force measuring frame. In the second part wave impacts were recorded by pressure cells at 22 positions of the caisson. The investigation contained two main items which are discussed in this paper: Comparison of quasi-static wave forces with maximum forces by wave impacts. Comparison of forces and impacts for a circular caisson with those measured for a square caisson.
MODELING ESTUARIAL COHESIVE SEDIMENT TRANSPORT
Authors: Hayter E.J. , Mehta A.J.
Published: June 2019

Cohesive sediment related problems in estuaries include shoaling in navigable waterways and water pollution. A two-dimensional, depth averaged, finite element cohesive sediment transport model, CSTM-H, has been developed and may be used to assist in predicting the fate of sorbed pollutants and the frequency and quantity of dredging required to maintain navigable depths. Algorithms which describe the transport processes of redispersion, resuspenslon, dispersive transport, settling, deposition, bed formation and bed consolidation are incorporated in CSTM-H. The Galerkin weighted residual method is used to solve the advection-dispersion equation with appropriate source/sink terms at each time step for the nodal suspended sediment concentrations. The model yields stable and converging solutions. Verification was carried out against a series of erosion-deposition experiments in the laboratory using kaolinite and a natural mud as sediment. A model application under prototype conditions is described.
WATERQUANTITY AND -QUALITY RESEARCH FOR THE RHINE MEUSE ESTUARY
Authors: Roelfzema A. , Karelse M. , Struijk A.J. , Adriaanse M.
Published: June 2019

In commission of the Dutch Government (Ministry of Public Works), the Delft Hydraulics Laboratory carries out a long term research programme on the water quantity and water quality of the Rhine-Meuse estuary. The research programme has to provide the necessary hydraulic data as Input for a management decision-making process. The programme is based on an "integrated approach philosophy" with respect to the various subjects to be studied and the research tools to be used (data from nature, hydraulic model, mathematical models and fundamental research). The paper presents the essentials and backgrounds of the research programme and discusses some first results.
STABILITY PARAMETERS OF WESTERN SCHELDT ESTUARY
Authors: De Jong H. , Gerritsen F.
Published: June 2019

The Western Scheldt is a major estuary in the Southern part of The Netherlands and the Northern part of Belgium. It is an important navigational route connecting the city of Antwerp with the North Sea. At the entrance Vlissingen is a major Dutch port.
EFFLUENT DISPERSAL IN EUROPEAN COASTAL WATERS
Authors: Prandle D.
Published: June 2019

The mixing of dissolved material discharged from the Windscale nuclear re-processing plant is examined. The first phase involves a numerical modelling study of large-scale long-term mixing over the entire Continental Shelf. The second phase involves a similar modelling study of near-source mixing processes over a region some 100 km square immediately adjacent to the discharge position. In this latter phase, reproduction of instantaneous peak concentrations is required. The first phase of this simulation has been successfully completed while the second phase is presently being considered. Ironically, it is shown that this second phase poses far more difficult modelling problems and hence the accuracy of simulation attained in the first phase may not be reproduced. The contrasts in these two modelling approaches are examined and their varying complexities explained.
SEWAGE DISPOSAL IN SHALLOW COASTAL WATERS
Authors: Dette Hans H.
Published: June 2019

The disposal of sewage effluent into coastal waters for dilution and final disposal requires an effective mixing of sewage with the seawater in order to achieve the necessary or demanded reduction of bacterial population. Most of the design parameters originate from work done on ocean outfalls. RAWN et al. (I960) developped curves from field data for the determination of initial dilution in a waste issuing from a horizontal port. ABRAHAM (1963) extended these curves to show that the dilution is a function of the depth of discharge port, the diameter of the discharge orifice D and the FROUDE number F. The question, to which extent this calculation method is also valid for outfalls in shallow water regions, is still open. In connection with the actual design of a diffuser in shallow coastal water the method of ABRAHAM was applied together with a new method derived by BERGEN (1980) which is based upon experiments which were carried out in the Leichtweiss- Institute at semi-technical scale. After the diffuser had been taken into operation by means of in-situ measurements the demanded dilution could be checked and herewith also the reliability of the applied design method for practical use.
A NEW NUCLEAR DENSITY GAUGE TO MEASURE DIRECTLY HIGH TURBIDITIES IN MUDDY AREAS
Authors: Caillot A. , Meyer G. , Chambellan D. , Tanguy J.C.
Published: June 2019

A better knowledge of the characteristics of muddy areas, in access fairways and port basins, and of the behaviour of ships during their crossing, presents the double interest of enhancing the navigation possibilities, through a more precise adjustment of the ship draught to the status of the bottoms, and permiting a more rational organization of the maintenance dredging campaigns. Considerable savings will be obtained through the development of such knowledges for harbours management. These improvements imply the use of measuring equipments which must be handy, sturdy, reliable and which give accurate measurements. The JTD3 gauge presented by the Radioisotopes Applications Service of the French Atomic Energy Commission is an important step in the development of such measuring equipments. It is now in running order, and commercially available, after thorough test campaigns, undertaken during many months in different french harbours. New developments are already engaged, namely through the design of a turbidity gauge able to make dynamic measurements.
DEVELOPMENT OF SHIP WAVE DESIGN INFORMATION
Authors: Sorensen Robert M. , Weggel J. Richard
Published: June 2019

During the last three decades several field and laboratory investigations have been conducted in which the waves generated by a wide variety of vessels have been measured. There is a need to synthesize the data published from these studies and to develop general ship wave prediction methods for designers. To complete this task some additional ship wave data must be collected. This paper initiates the effort to develop these prediction methods. A summary and critique of available data are given. Then, the appropriate portion of these data is employed to develop a ship wave height predictor model that gives the maximum ship wave height as a function of ship speed and displacement, water depth, and distance from the sailing line. This is an interim model that is quite applicable but can be improved pending additional data. Finally, planned future efforts to further develop design wave prediction methods are discussed.
RUN-UP OF PERIODIC WAVES ON BEACHES OF NON-UNIFORM SLOPE
Authors: Ogawa Yoshinobu , Shuto Nobuo
Published: June 2019

Run-up of periodic waves on gentle or non-uniform slopes is discussed. Breaking condition and run-up height of non-breaking waves are derived "by the use of the linear long wave theory in the Lagrangian description. As to the breaking waves, the width of swash zone and the run-up height are-obtained for relatively gentle slopes (less than 1/30), on dividing the transformation of waves into dissipation and swash processes. The formula obtained here agrees with experimental data better than Hunt's formula does. The same procedure is applied to non-uniform slopes and is found to give better results than Saville's composite slope method.
FIELD STUDIES OF RUN-UP ON DISSIPATIVE BEACHES
Authors: Carlson Christopher T.
Published: June 2019

Field measurements of narrow-band incident wind waves and the resulting run-up were made photographically at two different natural sand beaches along San Francisco Bay. The run-up spectra derived from the field-measured time series show some energy at the incident-wave peak frequency, with the predominant run-up spectral energy concentrated in frequency bands below the incident-wave peak frequency. Observations of the swash time series recorded at both beaches indicate that the low-frequency run-up is generated on the beach face by the interaction between the run-up and backwash during the swash cycle. Coherence analyses indicate that the offshore incident waves and run-up on the beach are not linearly correlated but that the run-up is correlated in the alongshore direction. The slopes of the log-log run-up spectra computed over the frequency band of the incident waves are all approximately -3. Statistical hypothesis tests were used to compare the empirical run-up cumulative distribution functions with both normal and Rayleigh distribution functions.
PREDICTION METHOD FOR THE WAVE HEIGHT DISTRIBUTION OEF THE WESTERN COAST OE TAIWAN
Authors: Tang Frederick L.W. , Juang Jea-Tzyy
Published: June 2019

Taiwan Strait locates on the continental shelf of the western Pacific Ocean. The water depth is less than 100 meters. Furthermore, the bathemetry of the eastern side namely the offing of western coast of Taiwan shoals gradually. In consequence, in case of the wind "blows from the north to south, waves in the deeper part of the strait refract to he north west direction while they are approaching the shore and local waves directly generated by the wind still keep the same direction of the wind. The situation is shown in Figure 1. Erom September to April of the next year, anticyclones come from Mongolia causes monsoon in this area. The wind velocity in the monsoon sometimes exceeds 20 meters per second, but it is arround 10 meters per second in general. Howerer, the duration of winds over 5 meters per second has been recorded more than 50 days. Engineering works such as towing caissons for building breakwater as well as dredging offshore have to be done in these days. Furthermore, navigation operations should not be stopped unless the wind is too strong. Of course, waves are forecast every day, however, more precise information about the probability of the occurrence of certain wave height is of great significance. In last conference, the authors submitted a probability density function of wave heights in this area. This distribution model is to be remended by considering energy loss in this paper, and concrete forecasting procedure is submitted for engineering and navigation practice.
CALCULATION OF DIRECTIONAL WAVE SPECTRA BY THE MAXIMUM ENTROPY METHOD OF SPECTRAL ANALYSIS
Authors: Briggs MIchael J.
Published: June 2019

Two analysis techniques for calculating directional wave spectra from measured pressure and biaxial current components were intercompared using data from the 25 October 1980 Atlantic Remote Sensing Land Ocean Experiment (ARSLOE) storm. The two methods are the conventional Fast Fourier Transform (FFT) method and a Maximum Entropy Method (MEM). The MEM is a nonlinear data adaptive method of spectral analysis which is capable of generating higher resolution spectral estimates from shorter data records than conventional FFT methods. The MEM has shown good agreement with the frequency and directional wave spectra calculated using conventional methods.
WAVE ATTENUATION AND SET-UP ON A BEACH
Authors: Svendsen I.A.
Published: June 2019

A theoretical two-dimensional model for wave heights and set-up in a surf zone is described and compared to measurements. The integral wave properties energy flux Ef, and radiation stress Sxx are determined from crude approximations of the actual flow in surf zone waves. Some physical aspects of the outer region are discussed and found to agree with our knowledge of the waves seawards and shorewards of this region.
SWASH ON STEEP AND SHALLOW BEACHES
Authors: Guza R.T. , Thornton E.B. , Holman R.A.
Published: June 2019

Extensive field observations of swash on natural beaches are used to relate the magnitudes of swash oscillations to incident wave conditions and the beach slope. Swash fluctuations at wind wave frequencies (defined here as f > .05 Hz) appear to be "saturated." As in laboratory experiments with monochromatic waves, wave breaking prevents the magnitudes of swash oscillations at incident wave frequencies from increasing past a certain level which depends on the beach slope. All data sets considered support this conclusion. In contrast, the magnitude of swash oscillations at surf beat frequencies (defined as f < .05 Hz) varies between data sets. Possible reasons for the discrepancy are discussed. Despite their differences, all data sets show that motions at surf beat frequencies dominate the swash spectrum on dissipative beaches. As in previous studies, the frequencies of spectral hills and valleys in the spectra of surf zone sensors suggests that a significant fraction of the surf beat energy is contained in motions which are standing in the cross-shore direction. Preliminary analysis indicates that shoreward propagating surf beat is coupled to incident wave groups.
MEASUREMENTS OF SURF BEAT AND SET-DOWN BENEATH WAVE GROUPS
Authors: Kostense J.K.
Published: June 2019

A laboratory study was conducted to measure the amplitudes of long waves In shallow water as induced by wave grouping. In a 55 m long wave channel with a plane beach at the end, two primary waves of nearly equal frequency were generated. Due to a sophisticated control of the wave paddle - including second order wave generation as well as active wave absorption at the paddle face - the wave action at the difference frequency was limited to an incident forced wave, propagating at the group velocity, and a reflected free wave generated in the surf zone. For the incident forced - or bound - wave, also known as set-down, the experimental results show good agreement with the existing theory. Furthermore, the experiments confirm qualitatively a theoretical model by Symonds et al. (198 2) explaining two-dimensional surf beat as a result of the time-varying breakpoint of the incident primary waves.
WAVE KINEMATICS AND DIRECTIONALITY IN THE SURF ZONE
Authors: Van Heteren J. , Stive M.J.F.
Published: June 2019

Measurements of surface elevations and internal velocities have been conducted in a natural surf zone. The results were used to investigate the quantitative performance of linear theory in predicting the wave kinematics from the surface elevations. It appears that linear theory systematically overpredicts the horizontal velocities by 20 % in the frequency range around the peak, where the coherence with the surface motion is high, by 15 % at 2 times the peak frequency, changing in an underprediction of 15 % at higher frequencies. In these higher frequency ranges the rate of turbulent energy induced by breaking, contributes to the variance, so that the ratio of measured to theoretical r.m.s. fluctuation shows a trend of 25 % theoretical overprediction at negligible turbulent energy rates to 5 % underprediction at high turbulent energy rates. Furthermore the results were used to investigate the linear prediction of radiation stress and the effect of directionality on the radiation stress. Prediction of the radiation stress by unidirectional, linear theory gives an overestimation of 50 % at negligible turbulent energy rates to 35 % at high energy rates, which percentages reduce to 45 % and 25 i when the effect of shortcrestedness is taken into account.
THE PROBABILITY CHARACTERISTICS OP WAVES AND WAVE PRESSURES AT A VERTICAL BREAKWATER
Authors: Peiji Huang , Binglai Zhao
Published: June 2019

In this paper, under the condition of waves in front of a breakwater being not broken, studies were made on the characterises of probability distribution of waves and wave pressures, the regularity of the spectral component attenuation with depth and the constitution of the high frequency band of wave pressure spectrum. The distributions of wave heights in front of a vertical breakwater, the range of wave pressure fluctuation at different subsurface levels, and the wave periods have shown that they are practically invariable with depth and can be determined theoretically. The spectral constitution of wave pressure field and the regularity of attenuation of spectral components were analyzed at the vertical breakwater, and a new expression describing the equilibrium range of wave pressure spectrum was obtained.
WAVE MEASUREMENT WITH DIFFERENTIAL PRESSURE GAUGES
Authors: Bodge Kevin R. , Dean Robert G.
Published: June 2019

The potential error of estimating the small pressure gradient under a directional wave field through the subtraction or comparison of relatively large total-head signals from adjacent pressure transducers in an array is avoided through the use of differential pressure transducers which measure directly the pressure gradients. A device which utilizes four differential pressure tranducers placed orthogonally about one absolute pressure transducer, (the "DPG"), was developed and field-tested at the U.S. Army Corps of Engineers Coastal Engineering Research Center Field Research Facility, Duck, North Carolina. The first five directional Fourier coefficients of the directional ocean spectra were developed from the DPG data, and although no other in_ situ directional wave monitors were available for comparison, the directional peak determined from the DPG agreed well with simultaneous High Frequency (HF) radar data. The DPG instrument is about one-half the size and less than one-sixth the weight of conventional pressure sensor arrays. The field establishment of the orientation of directional-measuring instruments is also discussed.
WAVE-INDUCED OSCILLATIONS IN HARBORS WITH WAVE-ABSORBING QUAY
Authors: Yoshida Akinori , Ijima Takeshi , Okuzono Hideaki
Published: June 2019

An artificial wave-absorber (wave-absorbing quay) has come to be widely used to counteract excessive wave action on ships and structures in harbors. Its two-dimensional characteristics on wave absorption have been investigated with several types of the wave-absorbing quay theoretically as well as experimentally, e.g., Jarlan (5), Terret, Osorio and Lean (9), Ijima, Tanaka and Okuzono (3), and Ijima and Okuzono (4), but the effects on the wave reduction in harbors seem to be not fully clear. This may be due to the lack of analytical methods for solving wave-induced oscillations in harbors with the wave-absorbing quay. When the side wall in the harbor basin is assumed to be perfectly reflective, many theoretical methods for solving wave-induced oscillations in harbors have been presented: Ippen and Goda (2) solved the problem of a rectangular harbor by using the Fourier Transform technique. Hwang and Tuck (1) presented powerful method, which is applicable to arbitrary shaped harbors, by using integral equation (source distribution along the boundary) for the expression of the velocity potential. A similar method to that of Hwang and Tuck, but more suitable one for numerical computation, was presented by Lee (6), who used integral equation separately in the harbor basin and in the open sea. Raichlen and Naheer (8), Mattioli (7), and Yoshida and Ijima (10) presented the methods being applicable to the harbors of arbitrary shape and variable depth by further extending Lee's method.
STEEP UNSTEADY WATER WAVES: AN EFFICIENT COMPUTATIONAL SCHEME
Authors: Dold J.W. , Peregrine D.H.
Published: June 2019

A new method for computing the unsteady motion of a water surface, including the overturning of water waves as they break, has been developed. It is based on a Cauchy theorem boundary integral for the evaluation of multiple time derivatives of the surface motion. The numerical implementation of the method is efficient, accurate and stable.
THE EXACT SOLUTION OF THE HIGHEST WAVE DERIVED FROM A UNIVERSAL WAVE MODEL
Authors: Chen Yang Yih , Tang Frederick L.W.
Published: June 2019

The solitary wave is first established in this paper by extending the series solution of periodic gravity wave as the wavelength approaches to infinite. Then, the highest gravity wave of permanent type in finite depth of water is immediately analyzed. The maximum ratio of wave height to water depth is obtained as 0.85465')..., and the angle at the crest for the considered highest wave is estimated to be 90°.
MEASUREMENTS OF MASS TRANSPORT OVER A ROUGH BED
Authors: Sleath J.F.A.
Published: June 2019

Measurements have been made with a laser doppler anemometer of the time-mean velocity of the fluid close to the bed in a wave flume. Both a rough bed, consisting of gravel of median diameter 11 mm, and a smooth bed were investigated. With the rough bed the time-mean velocity at a given height was found to be strongly dependent on position relative to prominent roughness elements. At one point the time-mean drift at a given height might be in the direction of wave propagation while, at another, in the opposite direction. Significant variation in time-mean drift with horizontal position was observed at all values of Reynolds number tested. The effect of bed roughness on the average value of the time-mean velocity at a given height was found to be most marked at low Reynolds numbers: the maximum near bed value with this gravel bed was about 3 times that for a smooth bed at the lowest Reynolds numbers tested. At the highest Reynolds numbers there was no clear difference between the rough and smooth bed values even though the boundary layer over the rough bed was fully turbulent whereas that over the smooth bed was laminar. However, at these high Reynolds numbers both the rough and the smooth beds showed a reduction in drift velocity below that predicted by Longuet-Higgins (9) because of the increased importance of higher harmonics in the flow.
SAND TRANSPORT BY WIND ON A WET SAND SURFACE
Authors: Hotta Shintaro , Kubota Susuma , Katori Sadakazu , Horikawa Kiyoshi
Published: June 2019

Using those results which were judged to be reasonable among various experiments, an equation predicting the threshold shear velocity on a wet sand surface was obtained. Then, based on a literature survey, results from fundamental experiments, and information obtained from a series of field observation carried out by the authors, a hypothesis to explain the blown sand phenomena on a wet sand surface was developed. Experiments with a well-sorted sand having a median diameter of 0.3 mm showed that the prediction was valid if the water content of the sand layer was less than 8 %.
BAYWATER RESPONSE TO TSUNAMIS
Authors: Abe Tetsuo
Published: June 2019

To investigate the transient characteristics of the tsunami-induced oscillations, records of tsunami caused by the Off-Miyagi earthquake in June, 1978 were analysed on the basis of theories on stationary and nonstationary stochastic processes. The stationary spectra show the average feature of the phenomenon. Discrepancies, however,are recognized between the first half oscillations and the second half oscillations during the tsunamis. Besides, the energy densities of non-stationary spectra do not always indicate stationary value at the periods which correspond to the predominant ones of the stationary spectra. These suggest that tsunami induced oscillations are translative.
EXPERIMENTAL VERIFICATION OF SIMILARITY CRITERIA FOR EQUILIBRIUM BEACH PROFILES
Authors: Sayao Otavio S.F.J. , Guimaraes Jose Carlos
Published: June 2019

This paper presents an attempt towards the determination of the geometric distortion for beach mobile bed models. At first, a derivation of a scaling law for modelling equilibrium beach profiles is given, based on Valembois' (1961) work. Further, an experimental verification of some criteria presented in literature for the reproduction of beach profiles in coastal mobile bed models (e.g. Noda, 1971; Yalin, 1971 and Vellinga, 1982) is carried out, leading to a comparison with the criterion developed herewith. Model experiments were undertaken in a two-dimensional wave flume with regular waves in an attempt to verify the validity of the four similarity criteria for the reproduction of beach profiles. For fine sand as model material, the experimental results proved valid the modified criterion based on Valembois (1961), among all criteria used. The use of this similarity criterion showed that the beach profiles were correctly reproduced in the model. The use of cellulose acetate as model material did not give good results, and none of the similarity criteria used were verified. The use of this lightweight material should be avoided for modelling beach processes. Further testing with finer sand is recommended to analyse the influence of the dimensionless fall time parameter (Dean, 1973) and to confirm its use for the prediction of equilibrium beach profiles.
A MODEL FOR OFFSHORE SEDIMENT TRANSPORT
Authors: Stive M.J.F. , Battjes J.A.
Published: June 2019

Observation of the two-dimensional breaking of random waves on a beach suggests that under conditions of active surf an important mechanism in the process of offshore sediment transport is the transport by the undertow or return flow, induced by the breaking of waves. It is found that a model incorporating this mechanism exclusively is able to describe the local sediment transport and the resulting bottom variation of a beach under random wave attack to a first approximation. A laboratory verification is made based on measurements of both the dynamics of the water motion and the bottom profile. Finally, a realistic equilibrium state is shown to result from the model
CHANGING OF WAVE CLIMATE DUE TO BREAKING ON A TIDAL INLET BAR
Authors: Niemeyer Hanz Dieter
Published: June 2019

Changes of wave climate due to breaking on a tidal inlet bar are investigated by analysis of field measurements prosecuted offshore and onshore of the bar. Quantitative results for wave height reduction, period and length transformation and energy dissipation are presented as well as a study considering the dominating breaking criterion.
THE INTERACTION OF WAVES AND CURRENTS OVER A LONGSHORE BAR
Authors: Svendsen I.A. , Hansen J. Buhr
Published: June 2019

A two-dimensional model for waves and steady currents in the surf zone is developed. It is based on a depth integrated and time averaged version of the equations for the conservation of mass, momentum, and wave energy. A numerical solution is described based on a fourth order Runge-Kutta method. The solution yields the variation of wave height, set-up, and current in the surf zone, taking into account the mass flux in the waves. In its general form any wave theory can be used for the wave properties. Specific results are given using the description for surf zone waves suggested by Svendsen (1984a), and in this form the model is used for the wave motion with a current on a beach with a longshore bar. Results for wave height and set-up are compared with measurements by Hansen & Svendsen (1986).
NUMERICAL SIMULATION OF TURBULENT WAVE BOUNDARY LAYERS
Authors: Trowbridge J.H. , Kanetkar C.N. , Wu N.T.
Published: June 2019

This paper reports numerical computations of fully rough turbulent boundary layers produced by first and second order Stokes waves. The computations are based on a mixing length turbulence closure and on a slightly more sophisticated turbulent kinetic energy closure. The first order results compare well with existing laboratory results. Reversal of the second order steady streaming under relatively long waves, which has been predicted analytically, is also predicted in the numerical results, The steady second order velocity field is found to become fully established only after a development time on the order of a few hundred wave periods. Both the first and second order results indicate that advection and diffusion of turbulent kinetic energy play a minor role in determining the Reynolds averaged velocity field.
TRANSIENT RIPPLE FORMATION AND SEDIMENT TRANSPORT
Authors: Vongvisessomjai Suphat , Munasinghe L.C.J. , Gunaratna P.P.
Published: June 2019

A knowledge of sediment transport rates due to wave action is essential for an understanding of various coastal engineering problems. Many problems have to be resolved before successful measurement can be made for sediment transport rates due to waves. Since gradients of sediment transport cause changes of beach morphology, the sediment transport rate outside breaker can be determined from measured beach changes. Measurements of ripple growth and migration yield their mathematical descriptions in the same manner as those of surface waves. Expressions of sediment transport rates are then derived. It is found from the study that the sediment transport rates are strongly controlled by the rates of growth and migration of ripples.
A PROCEDURE FOR THE ANALYSIS AMD DESIGN OF CONCRETE ARMOR UNITS
Authors: Baird W.F. , Readshaw J.S. , Scott R.D. , Turcke D.J.
Published: June 2019

A rational approach to the design of rubble mound breakwaters that incorporates both the hydraulic stability and the structural integrity of individual concrete armor units is presented. A key element of this improved design procedure is the development of instrumentation to measure loads occurring on armor units in a physical model of a breakwater. Numerical methods have been employed to determine stresses throughout the armor unit once the loads are known and interaction design curves were developed from measured data. These interaction curves provide a useful assessment of the structural integrity of the armor units. The curves clearly demonstrate the overall factor of safety associated with the armor unit and the expected mode of failure. Based on the results of this type of analysis, the cost effectiveness and safety associated with different design alternatives may be explored and a breakwater that is both hydraulically and structurally efficient may be designed.
STUDY OF STATISTICAL CHARACTERISTICS OF IRREGULAR WAVE PRESSURE ON A COMPOSITE BREAKWATER
Authors: Chang Chien-Kee , Hwang Ching-Her
Published: June 2019

Wave pressure is the most important external force for the design of breakwater. During recent years, there has been considerable development in the technology of vertical face breakwater; however, there is no reliable method to compute wave forces induced by irregular waves. The purpose of this study is to obtain statistical characteristics of irregular wave pressure distribution from the data of model tests. The results of this study shown that vertical face breakwater under the action of irregular waves, some waves are reflected, so that the next wave breaks a critical distance resulting in a rapidly rising shock pressure on the breakwater. On the average, the wave pressure increase with incoming wave height, but the maximum wave force does not necessarily occur for the largest wave height. It can be occurred for serval larger wave group in an appropiate phase composition. The irregular wave pressure distribution on the breakwater is quite uniform; the ratio of tested and calculated wave pressures decreases with the reduction of relative crest height of breakwater. Coda formula can predict the total horizontal force of the upper part of breakwater quite well except exetreme shock pressure occurred by non-breaking waves. Wave forces calculated by Miche-Rundgren and Nagai wave force formula are about 10% cummulated exceeding percentage of wave force obtained from model test.
SCOUR ABOUT A SINGLE, CYLINDRICAL PILE DUE TO COMBINED RANDOM WAVES AND A CURRENT
Authors: Eadie Robert W. , Herbich John B.
Published: June 2019

There have been many studies of scour around piles caused by waves, and some studies of scour by waves and currents combined. However, almost all of the studies were conducted with monochromatic waves. The purpose of this investigation was to study what scouring effects various currents and random waves have on a single, cylindrical pile. These results were then compared with the results from previous studies of scour resulting from currents and monochromatic waves at Texas A&M University (Armbrust, 1982 and Wang, 1983). Experiments were conducted in a two-dimensional wave tank. The pile used in this study had a diameter of 1.5 inches. Two water depths, four currents, one sediment size and four random wave spectra were utilized. Using data obtained from the experiments, an attempt was made to describe scour in terms of relevant dimensionless parameters.
APPLICATION OF A NESTED NUMERICAL MODEL TO IDEALISED RECTANGULAR HARBOURS
Authors: Falconer Roger A. , Mardapitta-Hadjipandeli Lida
Published: June 2019

The paper gives details of a two-dimensional depth averaged nested numerical model and its application to a range of idealised rectangular harbours, having a constant plan cross-sectional area and varying length to breadth ratios. The main aims of the study have been to investigate the problems associated with nested numerical modelling and to apply this modelling approach to assess the influence of the shape of a harbour on its natural tidal flushing efficiency and mixing characteristics.
WAVE ENERGY DISSIPATION IN ARBITRARILY SHAPED HARBOURS OF VARIABLE DEPTH
Authors: Kostense J.K. , Meijer K.L. , Dingemans M.W. , Mynett A.E. , Van den Bosch P.
Published: June 2019

A finite element model for combined refraction-diffraction problems of linear water waves has been extended to include the effect of various dissipative mechanisms on wave excitation response in harbours of arbitrary shape and variable depth. Especially, the effects of bottom friction, partial absorption along the harbour, contours, and transmission through permeable breakwaters have been considered. Although, within the mild slope approximation, the model is valid for arbitrary wave lengths, in this paper its effectiveness for harbour design applications is demonstrated for long wave induced resonance phenomena. For this purpose a realistic harbour geometry has been selected. A hydraulic scale-model of this harbour enabled experimental verification of the computational results.
THE STRUCTURAL RESPONSES OF DOLOS ARMOR UNITS UNDER THE DYNAMIC LOADING
Authors: Lin Wei-Ming , Rau Cheng , Su Rea-Lon
Published: June 2019

The "Dolos" is now used widely for harbor and shore protection works in various ports of Taiwan (R.O.C.) and some damage has been noted. The purpose of this research is to understand the major factors which influence dolos breakage. The factors studied include plain or reinforced concrete, rebar arrangement, chamfered or enlarged fillet corner and the fracture behavior by pendulum and drop test. Site observations and laboratory dynamic tests are included in this paper. The site observation investigated the behavior of the broken dolos at each habor. In the laboratory dynamic tests 42 specimens of 1.5 tons dolos were used for drop tests; frontal and transverse pendulum tests (Fig.l). The results show that the fracture behavior in the laboratory tests agree with those of site observation, i.e. cracking due to frontal impact is more severe than that of transverse impact. The arrangement of rebar also influences the strength of the dolos. Therefore, it is suggested that the dynamic tests are necessary for dolos testing.
PROTOTYPE EXPERIENCE WITH RUBBLE MOUND BREAKWATERS
Authors: MacIntosh K.J. , Baird W.F.
Published: June 2019

At the 19th ICE Conference in Houston in 1984 an alternative concept for the design of rubble mound breakwaters was introduced. This concept has the objective of providing a least cost structure by optimizing the use of locally available materials and utilizing simple construction procedures. Contractors' bids demonstrated that significant cost savings could be achieved, when compared to the cost of traditional designs. Considerable prototype experience has now been obtained with this concept of breakwaters. Breakwaters have been built using the concept in Canada, the United States, and Iceland since 1984 and have been subjected to storms and ice action. Prototype observations have supported the performance predicted during the design process. In this paper surveys of a breakwater taken after construction and after storm action are presented. In addition to wave action, this breakwater has also been subjected to extensive ice action. The response of the breakwater has been monitored and observed and is discussed.
ANALYSIS OF PERMEABLE BREAKWATERS
Authors: Murakami Hitoshi , Hosoi Yoshihiko , Goda Yoshitaka
Published: June 2019

This paper discusses the characteristics of hydraulic and water exchange due to the wave action against vertical slit-type breakwaters. The theoretical solution of the reflection and the transmission coefficients for the breakwater models is compared with the experimental results. Furthermore, the water exchange discharge and the water concentration change through the gap of the permeable breakwater are examined experimentally. Finally the most effective geometry of the cross section is suggested for the breakwaters used here.
DEVELOPMENT OF DESIGN CRITERIA FOR SEGMENTED BREAKWATERS
Authors: Pope Joan , Dean Julie L.
Published: June 2019

This paper will discuss experience and approaches to the use of segmented breakwaters for beach erosion control in the United States. Several prototype cases are examined and generalizations drawn concerning the resultant beach response. This experience is further evaluated in order to develop a preliminary approach for developing design criteria.
A NEW DESIGN METHOD OF RUBBLE MOUND STRUCTURES
Authors: Ryu Cheong-Ro , Sawaragi Toru
Published: June 2019

A new design method of rubble mound structures with stability and wave control consideration is proposed, by which the reduction of wave reflection and run-up and increase in rubble stability are assured under the given wave conditions. Wave control and stability increasing functions due to change of the slope shape of rubble mound structures are discussed on the basis of the experimental results for regular and irregular waves. The new design formula developed here considered the allowable percentage of damage and the wave grouping effects on rubble stability using a new assumption of the mean run-sum as an index of the irregular wave force. The run-sum is defined as the energy sum of a run satisfying a critical wave condition and the mean run-sum is the mean of run-sum for a irregular wave train.
REFLECTION OF IRREGULAR WAVES AT PARTIALLY REFLECTING STRUCTURES INCLUDING OBLIQUE WAVE APPROACH
Authors: Scheffer Hans-Joachim , Kohlhase Soren
Published: June 2019

The reflection of irregular seas is increasingly considered in coastal engineering and harbour design as well with respect to wave pattern at the structure and energy dissipation as regarding the dimensioning of structures exposed to waves. It becomes evident that the three-dimensional sea state (oblique wave approach, irregularity of the waves) at partially-reflecting structures of a complex design cannot be described by means of a constant reflection coefficient alone, as is common practice. This is due to the fact that the coefficient is largely frequency-dependent and the physically effective reflection point of the structure cannot be clearly specified. In the light of this, basic investigations on wave reflection have been performed with different partially-reflecting structures, wave spectra and wave approach angles. In addition to laboratory experiments using both a wave flume and a wave basin, a theoretical solution based on diffraction theory was determined to describe the wave field in the reflection area of various structures. The investigations were restricted to non-breaking wave conditions. The reflection behaviour of structures is expressed by a complex reflection coefficient, containing two parameters, which have to be determined by model tests.
SCALE EFFECTS ON STABILITY AND WAVE REFLECTION REGARDING ARMOR UNITS
Authors: Shimada Atsuyuki , Fujimoto Toshimi , Saito Syozo , Sakakiyama Tsutomu , Hirakuchi Hiromaru
Published: June 2019

In the studies on stability of the armor units and reflection from those, there are some indications on scale effects which are included in the results of small scale experiments. In this study, the fact has been confirmed with large wave flume test, and estimated the critical Reynolds Number where was no scale effect. And by this result on the stability of urmor units, we can evaluated the results in small and middle scale test, and can correct the minimum weight of armor units. So we can design the breakwaters and seawalls rationaly and economicaliy. However, it has not been confirmed the critical Reynolds Number where the influence of scale effect on reflection became negligible.
THE INFLUENCE OF OBLIQUE REFLECTION ON BREAKWATERS
Authors: Silvester Richard
Published: June 2019

The degree of reflection from rubble-mound breakwaters, even those comprising large pre-cast concrete armour units is greater than is usually thought. This is because the bulk of the face consists of smaller stones where water exchange in voids is minimal. Theory and experiment have shown that for 100% reflection of oblique waves the orbital motions are very complex, varying across the crest length of the short-crested system from rectilinear oscillation to circular or vortex motion. Also the influence of these high velocity orbital motions on a sedimentary bed have been shown to have a high scouring capacity. This has been exhibited in hydraulic models and in the field.
MEDITERRANEAN SEA LEVEL CHANGES FROM TIDAL RECORDS
Authors: Goldsmith Victor , Gilboa Michael
Published: June 2019

Of the more than 90 tide gage records in the Mediterranean, 10 representative gages were analyzed for indications of sea level rise (SLR). No definitive trend of regional sea level rise has been discerned for this area. The lack of SLR may be partially attributed to local effects on sea level such as seasonal water temperature and wind differences, and to local tectonics. The extent of these seasonal changes is in the order of tens of cms/year, and varies greatly from year to year, probably masking the trends of long-term SLR of mm/yr.
ANALYSIS OF BEACH EROSION AROUND LARGE-SCALE COASTAL STRUCTURES
Authors: Uda T. , Sumiya M. , Kobayashi Y.
Published: June 2019

The coast of Ibaraki Prefecture, facing the Pacific Ocean, has an alongshore stretch of 181 km. On this coast many structures associated with harbors have been constructed since early 1960s. Since then 25 years have passed, and some notable beach changes due to the influence of the construction of the coastal structures have been observed. This study aims to examine the actual situation of the beach change around large-scale structures and the damages of the coastal structures selecting the coast of Ibaraki Prefecture as the study area. For the purpose aerial photographs were taken along the coast, and the topographic surveys and measurements of median diameter of beach-face materials were made. Data of the soundings having been conducted once a year since 1975 around Oharai Port and Hazaki Fishery Harbor were collected in order to study the beach changes around the large-scale coastal structures. For the analysis of these data the comparison of the shoreline changes were performed by using four sets of aerial photographs since 1947 to the present. Moreover, temporal and spatial changes of the beach topography were investigated by the sounding data.
STRUCTURAL BEHAVIOUR OF TEN TON DOLOS ARMOUR UNITS
Authors: Uzumeri S.M. , Basset R.
Published: June 2019

This paper summarizes the results of a research program conducted to examine the structural behaviour of nine full scale ten ton Dolos armour units subjected to a well defined loading regime. Three unreinforced and six reinforced units were tested. The effects of three different types of reinforcement (rebars, hollow steel tubes, and prestressing bars) on the behaviour of the units was determined. Different design approaches for armour units are discussed and one possible new approach is presented.
DOLOS ARMOUR DESIGN CONSIDERATIONS
Authors: Zwamborn J.A. , Scholtz J.D.P.
Published: June 2019

The dolos armour unit has been used all over the world and, although most projects have been successful, there have also been some major failures. When moved around, armour units in general and the rather slender dolosse in particular are prone to structural damage and when dolosse break through the shank, one is left with very unstable pieces of rubble. It is shown in this paper that a safe and economic dolos structure can be obtained if the correct design process is followed. The "optimum" design is based on a reasonable degree of dolos movement which must be established in detailed and representative model tests. To ensure that the dolosse can withstand these movements, prototype dolos behaviour must be monitored, and such monitoring must be supplemented by representative structural tests, analytical studies and special prototype measurements. To increase the structural strength of dolosse, the waist to height ratio can be increased and some (simple) form of reinforcing can be included.