bluuebunny/crossref_metadata_2025 huggingface dataset:
MULTIPLE REGRESSION ANALYSIS OF EFFECTS OF BAR AND TIDE ON SHORELINE CHANGE
Authors: Banno Masayuki , Kuriyama Yoshiaki
Published: December 2012

The effects of bars and tides on shoreline change were investigated by a multiple regression analysis. The shoreline change rates used for the analysis were estimated from the beach profiles measured every workday during a 22-year period from 1986 to 2007 on the Hasaki coast in Japan. The examined parameters which had the potential to affect shoreline change rates were offshore wave energy fluxes, previous shoreline positions, maximum, minimum and average tides, and inner and outer bar crest elevations. In the multiple regression analysis, parameters which affected the shoreline change rate were selected by comparing the multiple regression models developed by combining the parameters on the basis of the Akaike Information Criterion (AIC) value, and the effects were also estimated by using the coefficients of the best model which had the smallest AIC. The shoreline change was affected by not only the offshore wave energy fluxes and the previous shoreline positions but also the maximum and minimum tides and the inner and outer bar crest elevations. The largest effect was the offshore wave energy fluxes, followed in order by the maximum tides, the previous shoreline positions, the minimum tides, the outer bar crest elevations and the inner bar crest elevations.
A NOVEL CELLULAR AUTOMATA APPROACH TO ESTUARINE MORPHODYNAMIC MODELLING
Authors: Bentley Ian , Karunarathna Harshinie
Published: December 2012

The need for reliable modelling techniques for the prediction of morphological change in coastal settings has become increasingly important to coastal planners and policy makers in recent years due to the effects of accelerated sea level rise and a shift in approach from coastal defence to coastal management. In this research a new cellular automata based model is developed in order to bridge the gap between current bottom-up, process based models and top-down behaviour oriented models of estuarine morphodynamic evolution, and make predictions of morphological change over medium time-scales (one year to several decades). The key processes of tidal flows, waves, sediment transport and salt marsh ecology are represented in simplified form in order to capture the complex interactions and feedbacks that occur between them and which ultimately determine how the morphology will develop in response to environmental change. The initial bathymetry of the estuary is represented by a cluster of rectangular cells in a CA domain. Tidal flows are estimated using a new routing model, which shows good agreement with a conventional 2D hydrodynamic model but is much more computationally efficient.
PROCESS-BASED MODELING OF COASTAL DUNE DEVELOPMENT
Authors: Muller Martijn Christiaan , Roelvink Dano , Luijendijk Arjen , De Vries Sierd , Van Thiel de Vries Jaap
Published: December 2012

In this paper, the aeolian transport model DUNE (Sauermann et al., 2001, Kroy et al., 2002) that describes important features and dynamics of typical desert dunes, is extended such that it can be applied in sandy coastal areas. Initial tests explore the limitations of the model in coastal areas after which adaptations are proposed and implemented. The final model version is applied to a coastal profile near Vlugtenburg (Dutch Holland coast).
PREDICTION OF DEVELOPMENT OF SAND SPITS AND CUSPATE FORELANDS WITH RHYTHMIC SHAPES CAUSED BY SHORELINE INSTABILITY USING BG MODEL
Authors: Serizawa Masumi , Uda Takaaki , Miyahara Shiho
Published: December 2012

The BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept) was used to simulate the shoreline evolution caused by the high-angle wave instability discussed by Ashton et al. Three calculations were carried out: the wave direction was assumed to be obliquely incident from 60Ëš counterclockwise (Case 1) or from the directions of ±60Ëš with probabilities of 0.5:0.5 (Case 2) and 0.65:0.35 (Case 3), while determining the incident wave direction from the probability distribution at each step. The three-dimensional development of multiple sand spits and cuspate forelands with rhythmic shapes was successfully explained using the BG model. The results of the previous study conducted by Ashton et al. were reconfirmed and reinforced.
EXPERIMENTAL INVESTIGATION ON DYNAMIC EQUILIBRIUM BAY SHAPE
Authors: Weesakul Sutat , Tasaduak Somruthai
Published: December 2012

Equilibrium bay is a bay that its shoreline is stable and does not change with time in long term. This concept can be applied for coastal protection. Experiments on dynamic equilibrium bay planform are conducted in a laboratory. There is one location of sediment supply source into a bay near upcoast headland and its magnitude vary from case to case. Wave obliquity varies from small to moderate values. These are two main parameters while wave condition is kept constant. The final bay planforms are investigated and recorded once they reach equilibrium with condition that sediment transport gradient approaches zero and no further shoreline change are observed. The parabolic equation similar to that for static equilibrium is newly proposed. The coefficients are originally derived and found to be a function of wave obliquity and the ratio of sediment supplied into bay to longshore sediment transport. The new dynamic equilibrium bay equation can be used and applied to study morphology change with variation of supplied sediment from inland.
EXPERIMENTAL STUDY ON THE EFFECTS OF THE OFFSHORE NOURISHMENT USING THE COASER SANDS WITH THE CROSS-SHORE SEASONAL CHANGE
Authors: Shibutani Yoko , Matsubara Yuhei , Kuroiwa Masamitsu , Yao Noriko
Published: December 2012

In recent decades, beach erosions have become severe at sandy beach in the world. The coarser sand nourishment has been noticed in Japan because of the stabilization of the beach coast. However the performance is not clear. Therefore in this study, laboratory experiments were conducted for the beach nourishment using the coarser sand. Through of this experiment, the effect of the coarser sand nourishment was investigated.
PROBABILITY OF EXCEEDING THE CRITICAL SHEAR STRESS FOR SAND MOTION IN SPECIFIC WAVE AND CURRENT CONDITIONS
Authors: Henry Pierre-Yves , T¸rum Alf , Artsen ˜ivind , Myrhaug Dag , Ong Muk Chen
Published: December 2012

This study is focusing on the threshold of sand motion under random waves combined with a following current. The analysis is based on some flume experiments realized over a natural sand bed for different flow conditions (waves and currents). The main result comes as a map of the probability to exceed the threshold of sand motion, as a function of a wave and a current mobility parameter. These observations are compared to methods predicting the bed shear stress using an equivalent monochromatic wave, and links between the probability of exceeding the critical shear stress for initiation of sand motion and the calculated maximum bed shear stress are found.
RIDGE-RUNNEL MIGRATION
Authors: Figlus Jens , Kobayashi Nobuhisa , Gralher Christine
Published: December 2012

The recovery of beaches after a storm can be influenced significantly by ridge-runnel migration. Ridges are made up of large volumes of sand which is important for the coastal sediment budget. The experiment described in this paper gives an insight into the complex hydrodynamics and sediment transport mechanisms related to onshore ridge-runnel migration. Detailed water free surface elevation, fluid velocity and sediment transport rate measurements were taken in a mobile bed wave flume with a focus on the effect of water ponding and runnel drainage on the profile evolution. The measured results have been used to calibrate the time-averaged numerical cross-shore model CSHORE. The model has the capability to deal with the effect of a pronounced profile depression (water-filled runnel) forming on the intermittently wet and dry zone of the beach. Results of the experiment compared with the corresponding numerical model computations show that the rapid onshore migration of a ridge-runnel system under fairly energetic wave conditions can be computed with CSHORE but further improvements of the model are necessary.
SHEETFLOW SEDIMENT TRANSPORT UNDER SKEWED - ASYMMETRIC WAVES AND CURRENTS
Authors: Phuong Dong Le , Sato Shinji
Published: December 2012

Prototype scale laboratory experiments have been conducted to investigate the sheetflow sediment transport of uniform sands under different skewed-asymmetric oscillatory flows. Experimental results reveal that in most of the case with fine sand, the "cancelling effect†, which balances the on-/off-shore net transport under pure asymmetric/skewed flows and results a moderate net transport, was developed for combined skewed-asymmetric flow. However, under some certain conditions (T > 5s) with coarse sands, the onshore sediment transport was enhanced by 50% under combined skewed-asymmetric flows. Sand transport mechanism under oscillatory sheetflow conditions is also studied by comparing the maximum bed shear stress and the phase lag parameter at each half cycle. A comparison of measurements including the new experimental data with a number of practical sand transport formulations shows that the Dong et al. (2013) formulation performs the best in predicting the measured net transport rates over a wide range of experimental conditions
EFFECT OF SURFACE ROLLERS ON THE FORMATION OF CRESCENTIC BARS
Authors: Calvete Daniel , Ribas Francesca , De Swart Huib E. , Falques Albert
Published: December 2012

The formation of crescentic bars is examined using a morphodynamic model based in linear stability analysis. The effect of surface rollers for off-normal wave conditions is examined. The effect of the rollers is to increase the efolding times with increasing the angle of incidence. For angles large enough the formation of crescentic bars is even inhibit. The main effect of the rollers it be through hydrodynamics. The longitudinal changes in current produced by the rollers cause the maximum of sediment concentration to be shifted towards the coast with the final effect of prevent the formation of crecscentic bars.
THE MORPHOLOGICAL RESPONSE OF BEACHES PROTECTED BY DIFFERENT BREAKWATER CONFIGURATIONS
Authors: Lorenzoni Carlo , Postacchini Matteo , Mancinelli Alessandro , Brocchini Maurizio
Published: December 2012

A series of experimental tests on a 2D movable-bed physical model of the protected sandy beach of Gabicce Mare, on the central Adriatic Sea in Italy, is described. Three emerged and three submerged configurations of rubble-mound detached breakwaters, for beach protection, placed at different positions, were tested in the Ancona (Italy) wave flume and the obtained results were compared with those found for a structure-free configuration. Both wave dissipation and reduction of beach erosion efficiency under various wave conditions were obtained and, in particular, the short-term hydro-morphodynamic response of the different tested breakwater configurations.
LONG TERM BEACH EROSION: MORPHODYNAMIC CASE STUDY IN MONT-ROIG BEACH, SPAIN
Authors: Galofré Jordi , Galofré Jordi , Ortiz Dolores , Medina Raúl
Published: December 2012

Long term coastal erosion in beaches induced by long-shore sediment transport is an important aspect to be taken account in beach behavior. If anthropogenic impacts in coastal stretch (harbor, detached breakwaters, lack of sediments from streams and gullies, and urban pressure) interrupting long-shore currents and transport and decreasing sediment supply, the coastal equilibrium disappears. In this paper a case study is shown in order to analyze long term beach behavior in a coastal stretch affected by erosion. After a brief description of morphological aspects, causes and effects that have incidence on the case study area will be shown. General background and coastal works are detailed. The ideas based on a classical analysis of beach behavior are exposed and results obtained from bathymetric analysis and numerical models are showed. Morphology, wave climate, morphodynamics and sediment budget are evaluated and morphodynamic beach behavior is proposed. A diagnosis is made and mitigation proposal for coastal erosion will be proposed.
NUMERICAL AND EXPERIMENTAL STUDY OF DAM-BREAK FLOOD PROPAGATION AND ITS IMPLICATION TO SEDIMENT EROSION
Authors: Hsu Hung-Chu , Torres-Freyermuth A. , Hsu Tian-Jian , Hwung Hwung-Hweng
Published: December 2012

Regarding the hydrodynamics, within the past two decades it has become popular in numerical modeling of free-surface flow to adopt a Reynolds-averaged Navier-Stokes approach, where the volume of fluid (VOF) method is utilized to track the evolution of free-surface. However, this robust numerical model has not been widely applied to the study of sediment transport processes. In this study, we shall extend the numerical model to simulate suspended sediment transport and study the erosion pattern during the initial stage of the dam break flow. We also conducted a series of experiments in a horizontal channel of rectangular section and recorded the snap shots of surface profiles of a dam- break wave during the initial stage of dam-break. Measured data is utilized here to study the hydrodynamics and to validate the numerical model.
PHYSICAL MODELING STUDY ON SCOUR AND SCOUR COUNTERMEASURE FOR SEA-CROSSING BRIDGE PIERS
Authors: Chen Hsin Hung , Yang Ray-Yeng , Kuo Ping-Chiao , Hwung Hwung-Hweng
Published: December 2012

There are significant engineering challenges in placing the sea-crossing bridge piers in more or les shallow coastal waters because, as well as having to withstand storm-force waves and tidal currents, the bridge piers have to remain stable on a sea bed that may be continuously changing. One of the major challenges faced by designers is how to predict, and prevent, scour of the seabed sediments around the sea-crossing bridge piers. This paper describes a physical model study on scour and scour countermeasure for sea-crossing bridge piers. A 1:49 scale movable bed model tests were carried out in the Near-shore Wave Basin (NSWB, 27m x 19m) at the Tainan Hydraulics Laboratory, National Chang Kung University (NCKU), Tainan, Taiwan, with the sea-crossing bridge piers in the test area. Three series of physical model tests were performed in this study. The aim of the first test series is to investigate the maximum scour depth for the initial construction of bridge piers with only one pier model. Then the second test series were conducted to investigate the greatest magnitude of local scour and potential scour area in the sand bed around the sea-crossing bridge group piers with no scour protection. Based on the analysis from the former NSWB experimental results, the suitable scour countermeasure for sea-crossing bridge piers would be proposed and validated its function of preventing scour in the third test series.
3-D WAVE FIELD AROUND SUBMERGED BREAKWATER
Authors: Sharif Ahmadian Amir , Simons Richard
Published: December 2012

Methods for designing submerged breakwaters are still being developed, particularly in respect of the 3D nature of wave-breakwater interaction. Many of the available design tools are inefficient as they are not able to provide any information on the spatial distribution of the wave field around breakwaters, and cannot therefore guarantee reliability and accuracy for the engineer. There is thus a need for an engineering design tool with the ability to model spatial variation of wave height. This paper proposes a method based on machine learning algorithms for predicting the nearshore wave field behind a submerged breakwater that includes both 2D and 3D effects. The proposed numerical model has been validated by various scales of laboratory data. Comparisons reveal the ability of the proposed model to predict the wave field around submerged breakwater.
FORCES INDUCED ON A VERTICAL BREAKWATER BY INCIDENT OBLIQUE WAVES
Authors: Lara Javier , Higuera Pablo , Maza Maria , Del Jesus Manuel , Losada Inigo J. , Barajas Gabriel
Published: December 2012

Over the last years Navier-Stokes numerical models have been developed to accurately simulate wave interaction with all kinds of coastal structures, focusing on both functionality and stability of coastal structures. Although several models have been used to simulate wave interaction with coastal structures in two dimensions (2DV) there are a vast number of three-dimensional effects that need to be investigated in order to improve the design. In this paper a new model called IH-FOAM has been applied to study a vertical breakwater at prototype scale. As a first attempt of validation, the model has been used to simulate a regular wave train generated with a relative angle with the breakwater inducing three-dimensional wave patterns not only seaward the structure due to reflection but also generating an overtopping discharge variation along the breakwater trunk. Pressure laws and overtopping discharge at three different cross-sections along the structure have been studied. The pressure laws have been compared with classical Goda's formulation. Although, the numerical model predictions are in accordance with Goda's calculations, a clear three-dimensional variability of wave-induced pressure has been observed. Moreover, an additional study has been performed calculating pressure laws on the side-wall at the breakwater head. Large three-dimensional effects are detected from the simulations due to the flow separation at that area. Overtopping model predictions have been compared with Overtopping Manual calculations showing very close values along the trunk. However, lower overtopping discharge values are observed at the breakwater head. This paper is a preliminary work to show the range of applicability of a three-dimensional Navier-Stokes model to study wave interaction with a vertical breakwater under the action of an oblique wave train.
LABORATORY INVESTIGATION ON THE EFFECTIVENESS OF AN OVERSPILL BASIN IN REDUCING WAVE OVERTOPPING ON MARINA BREAKWATERS
Authors: Cappietti Lorenzo , Aminti Pier Luigi
Published: December 2012

This paper presents laboratory experiments on scale models of marina breakwaters conducted to assess the effectiveness of an overspill basin in reducing wave overtopping. Six different breakwater models were tested under eight different wave conditions. The comparisons between the overtopping measurements on a classical shaped breakwater model and those conducted on models characterized by the inclusion of overspill basins have proved the effectiveness of this new design. Moreover, increasing the height of the wave wall up to the value that induces the same reduction of the overtopping obtained by the inclusion of overspill basins is also reviewed. Some analysis on mean overtopping discharges as well as analysis on maximum overtopping volumes are reported.
ANALYTICAL INVESTIGATION OF SLAB BRIDGE DAMAGES CAUSED BY TSUNAMI FLOW
Authors: Murakami Keisuke , Sakamoto Yoshiko , Nonaka Tetsuya
Published: December 2012

Tsunami caused by Tohoku earthquake in 2011 had brought fatal damages on many kinds of infrastructures such as ports, roads, bridges, lifelines and other important structures. Among those damages, we have found many bridges whose superstructure was flooded away by tsunami flow. This study proposes a composite simulation method in order to investigate the damage on bridges caused by tsunami action. The numerical method consists of a hydraulic analysis and a structural one. The proposed method is applied to the damaged bridge whose superstructure was flooded away by Tohoku earthquake tsunami. Based on the structural analysis, this study discusses the mechanism of damage ã€€caused by tsunami flow. Furthermore, this study confirms the validity of hydraulic analysis through physical experiment.
INFLUENCE OF CUBE AND CUBIPOD ARMOR POROSITIES ON OVERTOPPING
Authors: Molines Jorge , Perez Tomas J. , Zarranz Guillermo , Medina Josep R.
Published: December 2012

This paper describes a series of small-scale tests which examined the influence of armor porosity on overtopping. The cube and Cubipod armored models corresponded to the Punta Langosteira Breakwater (A Coruña, Spain) during construction, when the primary layer is not in place and the crest freeboard is much lower. Overtopping rates for incomplete cross sections (those under construction) differed significantly from completed ones. After analyzing the variables influencing overtopping, new formulas were developed to estimate overtopping rates in a section during construction. Both the conventional Rc/Hm0 and the ratio Rc/d had a significant influence on overtopping rates of complete and incomplete cross sections.
WAVE REFLECTION GENERATED BY CAISSONS WITH INTERNAL RUBBLE MOUND OF VARIABLE SLOPE
Authors: Faraci Carla , Cammaroto Biagio , Cavallaro Luca , Foti Enrico
Published: December 2012

The paper reports on an experimental campaign focused on the performances of prefabricated caissons with internal rubble mound (combined caissons) in terms of incident wave energy reduction. The frontal opening and the chamber width of the caisson were changed in order to find the optimal design dimensions allowing the reflection coefficient to be reduced as much as possible. As expected, the best performances of the combined caisson occur when the rubble mound slope is gentler. The experimental results were also compared with an analytical model available in literature; such a comparison showed that the combined caisson exhibits a smaller reflection than predicted as far as wave periods higher than 8-9 s at a prototype scale are concerned.
LONG TERM PERFORMANCE OF A SUBMERGED COASTAL CONTROL STRUCTURE: A CASE STUDY OF THE NARROWNECK MULTI-FUNCTIONAL ARTIFICIAL REEF
Authors: Jackson Angus , Tomlinson Rodger , Corbett Bobbie , Strauss Darrell
Published: December 2012

In response to the increasing occurrences of beach erosion along Surfers Paradise and Main Beaches - Gold Coast, Australia, the Northern Gold Coast Beach Protection Strategy [NGCBPS] was developed to widen the beach by 20-30m as well as improving surfing conditions as a secondary objective. The strategy, implemented in 1999- 2000, involved large-scale beach nourishment and construction of a submerged breakwater "reef† to act as a control point at Narrowneck. Construction of the reef involved innovative filling and placement methods using very large sand filled geotextile containers coupled with significant advances with regards to design of the geotextile material and containers. In the 11 years since construction, there has been substantial monitoring of the project since its completion in late 2000 including: - video imaging using webcams; hydrographic and beach surveys; aerial and oblique photography; surf and surf safety observations and GPS surfing track plots; and geotextile container condition and stability. This paper presents an update on the performance of the reef over the last four years. In particular, the response of the structure and the shoreline to a series of major storm events in 2009 has been examined. The results have shown that the erosion caused by these major events was accommodated within the wider beach created in 1999. Over the next 2 years there was a gradual recovery in the lee of the reef with a subtle groyne effect resulting in an even larger increase in the width of the updrift beach. A detailed underwater condition survey was also undertaken in 2011, to determine changes in the condition of the geotextile containers. This revealed a number of containers missing or damaged, and that seaward containers were covered by sand. The marine habitat which has been a feature of the reef has been impacted by the increased coverage of sand, but still shows high abundance and biodiversity.
EXPERIMENTAL STUDY ON THE OVERTOPPING BEHAVIOUR OF STEEP SLOPES - TRANSITION BETWEEN MILD SLOPES AND VERTICAL WALLS
Authors: Victor Lander , Troch Peter
Published: December 2012

Extensive knowledge is available on the overtopping behaviour of traditional smooth impermeable sea defence structures, such as mildly sloping dikes and vertical walls, both typically featuring a high crest freeboard to reduce wave overtopping. A particular design application emerges in the development of wave energy converters of the overtopping type, where maximisation of wave overtopping is required, i.e. smooth impermeable steep sloping structures with low crest freeboards subjected to non-breaking waves. To date, only relatively limited knowledge is available on the overtopping behaviour of those structures. In this study, the average overtopping rate obtained from new experiments has been analysed and compared with existing prediction methods. This study contributes to a better knowledge on the overtopping behaviour of the steep low-crested structures, which is positioned in between that of mildly sloping dikes and vertical walls on the one hand, and in between that of structures with zero crest freeboards and relatively large crest freeboards on the other hand. The existing prediction methods seem unable to predict the significant effects of the slope angle and small relative crest freeboards on the average overtopping rate accurately. Therefore, a new set of prediction formulae is proposed based on the new experiments combined with existing data from literature. These formulae include wave overtopping at vertical walls subjected to non-impacting waves and at structures with zero crest freeboard.
DESTRUCTIVE WAVE OVERTOPPING AND WAVE RUN-UP TESTS ON GRASS COVERED SLOPES OF REAL DIKES
Authors: Steendam Gosse Jan , Provoost Yvo , Van der Meer Jentsje
Published: December 2012

In March 2011 new wave overtopping tests have been performed in the Netherlands. In contrast to previous tests the grass cover of this dike was not maintained well, which had significant effect on erosion stability. Additionally, for the first time a pilot test has been made on wave run-up from an asphalt berm onto the grass covered upper slope of the dike. The tested dike sections had a sand core covered by a layer of clay and a grass cover. The objective was to test the erosion stability of seaward and landward slopes for wave overtopping as well as wave run-up. For the wave overtopping also the influence on erodibility of the grass cover caused by obstacles or other elements, which may be present at dikes (stairs, fences), was investigated.
NEW DESIGN OF THE BALTRUM DUNE REVETMENT BASED ON HYDRAULIC MODEL TESTS
Authors: Thorenz Frank , Blum Holger , Kortenhaus Andreas
Published: December 2012

The sandy barrier island of Baltrum is located in the north-western part of the German Federal State Lower Saxony in the North Sea. The north-western part of the island is protected by a dune revetment against storm surges and erosion. In order to determine the functionality and loading of the construction under design storm surge conditions and investigate planning alternatives, numerical modeling of sea state conditions in combination with hydraulical model tests for the construction were executed. Measured overtopping rates of up to 125 l/(s.m) and loads up to 150 kPa showed the necessity to strengthen and heighten the initial construction. A combination of wall elements for wave run-up and overtopping reduction in combination with a crest wall were designed in order to meet the technical demands of coastal defence as well as the touristical needs of an important recreation locality.
EXPERIMENTAL STUDY OF PRESSURE DISTRIBUTIONS DUE TO THE BREAKING WAVE IMPACTS
Authors: Kisacik Dogan , Troch Peter , Van Bogaert Philippe
Published: December 2012

Results from wave impact tests are used to analyze the pressure distribution on a vertical structure with an overhanging horizontal cantilever slab. The structure faces two individual impacts, occurring sequentially on the vertical and horizontal parts. An expression is being proposed for the location of maximum pressures p_max (z_max) on the vertical part as a function of the wave steepness (Hâ,,L_0 ). The boundary conditions for occurring of high dynamic pressures are determined both on the vertical and horizontal part. Three different pressure distribution cases are proposed as SBW, BW and BWSAT according to the breaker type. For each breaker type, the local pressure ratio's p_h3â,,p_h1 , p_h1â,,p_v1 , and p_h2â,,p_v1 are analyzed, where p_h1, p_h2 and p_h3 are the local peak pressure at the SWL and top and bottom of the vertical part respectively, whereas, p_v1 is the local peak pressure on the horizontal part. Recommended profiles are calculated from local p_max values.
NUMERICAL MODELING OF TSUNAMI-INDUCED HYDRODYNAMIC FORCES ON ONSHORE STRUCTURES USING SPH
Authors: St-Germain Philippe , Nistor Ioan , Townsend Ronald
Published: December 2012

In this paper, the simulation of the violent impact of tsunami-like bores with a square column is performed using a single-phase, weakly compressible three-dimensional Smoothed Particle Hydrodynamics (SPH) model. In order to avoid large fluctuations in the pressure field and to obtain accurate simulations of the hydrodynamic forces, a Riemann solver-based formulation of the SPH method is utilized. Large-scale physical experiments conducted by the authors are reproduced using the numerical model. Time-histories of the water surface elevation as well as time-histories of the pressure distribution and net total force acting on the column are successfully compared. As observed in previous breaking wave impact studies, results show that the magnitude and duration of the impulsive force at initial bore impact depend on the degree of entrapped air in the bore-front. Although ensuring a stable pressure field, the Riemann solver-based SPH scheme is believed to induce excessive numerical diffusion, as sudden and large water surface deformations, such as splashing at initial bore impact, are marginally reproduced. To investigate this particular issue, the small-scale physical experiment of Kleefsman et al. (2005) is also considered and modeled.
SETTLEMENT MEASUREMENTS OPTIMISING CONSTRUCTION OF A BREAKWATER ON SOFT SOIL
Authors: Verhaeghe Hadewych , Van Damme Luc , Goemaere Jan , Boone Evy , De Rouck Julien
Published: December 2012

The need of an improved harbour access resulted into the construction of two new rubble mound breakwaters in Ostend, Belgium (Verhaeghe et al., 2010). Extensive soil investigation during the design phase of the breakwaters showed that the most northern part of the western breakwater is located in a zone containing a thick upper layer of soft material. To deal with the bad soil characteristics, a very strong geotextile was used to serve as a kind of armouring of the breakwater. An extensive analysis was carried out to determine how fast construction could go on, avoiding overall geotechnical failing, and to determine the settlements to be expected. During construction of the western breakwater, extensive settlement measurements were performed. This paper describes the settlement calculations performed with Plaxis2D versus the settlement measurements performed on site, leading to an optimised phasing of the construction works.
STABILITY OF RUBBLE MOUND BREAKWATERS AGAINST SOLITARY WAVES
Authors: Esteban Miguel , Morikubo Izumi , Shibayama Tomoya , Aranguiz-Muñoz Rafael , Mikami Takahito , Nguyen Thao Danh , Ohira Koichiro , Ohtani Akira
Published: December 2012

No formulas currently exist to design armour units against tsunami attack. To develop such formulae, laboratory experiments were carried out to clarify the failure mechanism of these types of structures. Also, the behavior of armour units against real cases of tsunami attack during the 2011 Tohoku tsunami were evaluated. Both the results of the laboratory experiments and the breakwaters studied in the field where then analyzed in terms of well established formulas such as that of Van der Meer or Hudson. The design of structures that only fail partially during a given tsunami event ("resilient† or "tenacious† structures) should be prioritized in future counter-measures, and in order to make it possible to construct such structures a modification of the Hudson formula for their design is proposed.
PARAMETRIC AND NON-PARAMETRIC METHODS FOR THE STUDY OF THE VARIABILITY OF WAVE DIRECTIONS: APPLICATION TO THE ATLANTIC URUGUAYAN COASTS
Authors: Solari Sebastián , Losada Miguel ngel
Published: December 2012

Wave direction is a fundamental variable in coastal engineering, whether one is interested in analyzing coastal processes or designing harbor structures. In this work a mixture of circular (wrapped) distributions is introduced for modeling the non-stationary probability distribution function of mean wave directions. The proposed distribution is able to accommodate seasonal and inter-annual variability, as well the influence of several climatic indices. This function was applied to the Atlantic Uruguayan coast, finding that both the Tropical South Atlantic index and the Antarctic Oscillation index have a significant influence on the variability of the wave directions.
THE EFFECT OF DIFFRACTION ON THE REDISTRIBUTION OF WAVE ENERGY IN THE LEE OF AN OVERTOPPING TYPE WAVE ENEGRY CONVERTER ARRAY
Authors: Monk Kieran Umit , Zou Qingping , Conley Daniel
Published: December 2012

A computationally efficient approximate analytical solution based on the classic solution for diffraction about a semi-infinite breakwater, is developed to assess the wave energy shadow down-wave of a single row array of overtopping type wave energy converters approximated as partially transmitting breakwater segments. The approximations associated with the solution are mitigated by a comparison with the mathematically exact but more computationally expensive boundary element method for the same problem. The approximate analytical solution is compared with a non-physical solution where diffraction is not accounted for to quantify the net re-distribution of wave energy by the diffraction mechanism with increasing down-wave distance from the array.
THEORETICAL AND NUMERICAL STUDY OF WAVE-CURRENT INTERACTION IN STRONGLY-SHEARED FLOWS
Authors: Dong Zhifei , Kirby James T.
Published: December 2012

The application of wave-current interaction theory in ocean circulation models has been extensively developed over the past decade, with formulations extended to three dimensions and based either on radiation stress formulations or on the Craik-Leibovich formulation. However, few of these studies consider the interaction of waves with relatively strongly sheared current, in which current shear can affect linear wave dynamics at leading order. The problem arises from the study of the evolution of highly concentrated sediment plumes developing at the mouth of small mountainous rivers. Although the annually averaged discharge of these small mountainous rivers is trivial compared to large rivers, during the extreme flooding events triggered by typhoon or tropic cyclones, these rivers, most of which located at tectonically active mountain belts, can carry highly concentrated sediment ( up to several g/l in the river plume) into the ocean. The magnitude of river discharge velocity at the river mouth may reach several m/s, comparable to the wave phase speed in coastal water. In addition, these flooding events usually coincide with very energetic wave conditions induced by the storms. Therefore, the interaction of waves with strongly sheared current becomes a very important dynamic process at this kind of river plumes. In our study, we establish a new framework to describe the interaction of small amplitude surface gravity waves and strongly sheared currents, where shear can exist in both vertical and horizontal directions. To begin with, we limit the derivation to the case of a narrow-banded slowly varying wave train propagating shoreward in the coastal ocean outside of the surf zone. Accordingly, our problem is assumed to be finite depth without wave breaking. Later we can extend the formulation to describe a spectrum of surface waves and include wave energy dissipation. In contrast to existing formulations, where waves at most feel a weighted depth-average current which follows from a weak-current, weak-shear approximation, the present formulation allows for an arbitrary degree of vertical shear, leading to a description of the vertical structure of waves in terms of solutions to the Rayleigh stability equation. The resulting formulation leads to a conservation law for wave action, and forcing terms for the description of mean flow using the Craik-Leibovich vortex force formulation. This new framework of wave-current interaction can be applied to numerical model based on ROMS/SWAN to study dynamics in coastal waters.
THE INTERACTION BETWEEN SHORT OCEAN SWELL AND TRANSIENT LONG WAVES: DISSIPATIVE AND NONLINEAR EFFECTS
Authors: Kaihatu James , Devery Deirdre , Erwin Richard , Goertz John
Published: December 2012

The dissipation and nonlinear effects of random swell interaction with transient long waves are studied. Results from a laboratory experiment in which random swell was generated both with and without a co-existing transient long wave are analyzed. An instantaneous dissipation mechanism for estimating both instantaneous and bulk dissipation from data is used to determine the characteristics of dissipation for both cases. Fourier analysis of the free surface measurements and dissipation estimates reveals that the presence of the transient long wave does not have an appreciable impact on the known dissipation characteristics of random swell. However, the use of wavelet analysis, centered on the long wave in the time series, shows that the dissipation characteristics of the combined short-long wave signals deviate considerably from that of swell alone, indicating that smearing of the long wave signal by the Fourier analysis is sufficiently strong to affect dissipation estimates. A wavelet-based bispectral algorithm is used to determine the nonlinear wave-wave coupling in both swell and combined swell-long wave signals; the results indicate that there can be broader ranges of frequencies in which nonlinear coupling is present for the case of the combined short-long wave signal.
THE EFFECT OF BED PERMEABILITY ON OSCILLATORY BOUNDARY LAYER FLOW
Authors: Sparrow Kathryn , Pokrajac Dubravka , Van der A Dominic A
Published: December 2012

This experimental study consists of a series of full-scale experiments involving oscillatory boundary layer flow over an impermeable bed and a permeable bed. Velocity measurements have been obtained through particle image velocimetry, and the effect of bed permeability on the velocity profile, phase lead, boundary layer thickness, bed shear stress (as estimated by fitting the log law), and finally the resulting friction factor is presented. For our rough turbulent flows over a permeable bed it has been found that the friction factor is increased by up to 36% and that the friction factor also demonstrates a dependence on Reynolds number.
THE USE OF ADV IN WAVE FLUMES: GETTING MORE INFORMATION ABOUT WAVES
Authors: Neves Claudio F. , Endres Luiz Augusto M. , Fortes Conceição Juana , Clemente Daniel Spinola
Published: December 2012

This article discusses the advantages of measuring wave orbital velocities in coastal two-dimensional physical models in addition to free surface profiles. A brief presentation of linear theory for partial standing wave is made and early experimental works on this subject are reviewed. Since 2005, additional experiments have been conducted on wave flumes in Brazil (INPH, IPH/UFRGS) and in Portugal (LNEC), in order to characterize wave patterns in terms of velocity data obtained by ADVs. A few questions are posed in the conclusion of the article, which aim at suggesting special care on the interpretation of velocity data, as used today, as well as proposing further research on the subject.
REMOTE SENSING AND DATA ASSIMILATION FOR SURF ZONE BATHYMETRIC INVERSION
Authors: Wilson Greg , Özkan-Haller Tuba , Holman Robert , Kurapov Alexander
Published: December 2012

We demonstrate the implementation and validation of a surf zone forecasting system, which uses remote sensing observations to control errors in surf zone bathymetry. This system uses ensemble-based sequential data assimilation techniques, which are adaptable to arbitrary geophysical observations, and/or arbitrary improvements to model physics. The system is validated using data from a 2010 field experiment at Duck, NC (U.S.A.), and is shown to produce accurate corrections to bathymetry, leading to improvements in prediction of currents.
EFFECTS OF TIDE ON WAVES IN THE OUTER SEINE ESTUARY AND THE HARBOR OF LE HAVRE
Authors: Guillou Nicolas , Chapalain Georges
Published: December 2012

The present study examines the influences of time-varying tide-induced water depths and currents on waves in the outer Seine estuary (southern central English Channel) and their penetration in the harbor of Le Havre and its new infrastructures Port 2000. The investigation is based on a numerical procedure which links regional phase-averaged wave modules with a local phase-resolving wave module within Port 2000 harbor. Required spatio-temporal evolutions of tidal free-surface elevation and current are computed by circulation modules. Numerical results of wave height are compared with field data collected at three wave buoys in the access harbor channel and its inner basin. Predictions exhibit a local increase (up to 30 %) of wave height induced by current refraction at slack tide in the access harbor channel. Respective mappings of the wave height modified by the tide, the water levels alone and the currents alone confirm this finding. The effect of currents on waves are pronounced along the southern breakwater of Port 2000 harbor and in the vicinity of coastal topographic features of the outer Seine estuary. Ultimate predictions of wave propagation within Port 2000 basin exhibit, however, the negligible direct influence of local ambient currents on wave height. Observed-semidiurnal wave-height variations in the inner basin are thus mainly associated with the propagation of the outer tide-induced modulation. Mappings of maximum wave-height within harbor basin reveal an increased exposition of the northern wharves at high tide and the southern western breakwater at low tide in relation to current-induced changes in the approaching-waves direction.
NUMERICAL INVESTIGATION OF TURBULENT BUBBLY FLOW UNDER BREAKING WAVES
Authors: Kirby James T , Ma Gangfeng , Derakhti Morteza , Shi Fengyan
Published: December 2012

We establish a framework for describing the spatial and temporal distribution of entrained air bubbles under breaking surface waves. The computational framework is based on a large eddy simulation (LES) in 3-D together with a VOF treatment of the air-water interface. An Eulerian multiphase approach is used in order to track the entrained bubbles as a number density distribution. Examples of numerical results for breaking periodic surf zone waves are illustrated.
COMPUTER SIMULATION OF MOORED SHIP MOTION INDUCED BY HARBOR RESONANCE IN POHANG NEW HARBOR
Authors: Kwak Moonsu , Moon Yongho , Pyun Chongkun
Published: December 2012

This paper proposes a computational method for estimating moored ship motion taking into consideration harbor resonance, and provides a way to estimate the effect that harbor resonance has on moored ship motion. The computation of harbor resonance used the CGWAVE model, and the computation of moored ship motion used the three-dimensional Green's function method. This method was verified with field motion measurement data from actual moored ships and wave field data and down time record data from Pohang New Harbor. The resonance periods obtained from wave field data in Pohang New Harbor were 80, 33, 23, and 8 min, which were the long waves, and 42, 54, and 60 s, which were the infra-gravity waves inside the harbor slip. The simulation results for harbor resonance were compared to the actual wave field data. This study investigated whether harbor resonance has an effect on moored ship motion using simulated results of ship motion both with and without harbor resonance included. In the case of harbor resonance included, moored ship motion increased by 10-30% when compared with the results without harbor resonance included. We found that harbor resonance has a greater effect on the surge and heave motion of a large-sized ship and on the roll and the yaw motion of a small-sized ship.
SHOALING OF NONLINEAR INTERNAL WAVES ON A UNIFORMLY SLOPING BEACH
Authors: Yamashita Kei , Kakinuma Taro , Nakayama Keisuke
Published: December 2012

The internal waves in the two-layer systems have been numerically simulated by solving the set of nonlinear equations in consideration of both strong nonlinearity and strong dispersion of waves. After the comparison between the numerical results and the BO solitons, as well as the experimental data, the internal waves propagating over the uniformly sloping beach are simulated including the cases of the mild and long slopes. The internal waves show remarkable shoaling after the interface touches the critical level. In the lower layer, the horizontal velocity becomes larger than the local linear celerity of internal waves in shallow water just before the crest peak and the position is defined as the wave-breaking point when the ratio of nonlinear parameter to beach slope is large. The ratio of initial wave height to wave-breaking depth becomes larger as the slope is milder and the wave nonlinearity is stronger. The wave height does not increase so much before wave-breaking on the mildest slope.
PROPERTIES OF FREAK WAVES INDUCED BY TWO KINDS OF NONLINEAR MECHANISMS
Authors: Tao Aifeng , Zheng Jinhai , Chen Botao , Li Hui , Peng Ji
Published: December 2012

We investigate the dynamic and kinematic characteristics of freak waves using a direct phase-resolved nonlinear numerical method. The focus is on the understanding of the effects of different nonlinear wave-wave interactions on freak waves development and characteristics in the evolution process of modulated Stokes wave trains. Long time simulations of modulated Stokes wave trains, with different parameters, are obtained. Based on these simulations, we find that there are different kinds of freak waves in different time scales due to two kinds of different nonlinear mechanisms. One is the modulation instability and another related to the wave group interaction. Both the dynamic and kinematic characteristics of the different kinds of freak waves are distinct. Occurrence of freak waves (especially of large height) is usually correlated with broadband wave spectra.
MIXING IN COASTAL AREAS INFERRED FROM LYAPUNOV EXPONENTS: IMPLICATIONS FOR TRANSPORT
Authors: Orfila Alejandro , Galan Alvaro , Simarro Gonzalo , Sayol Juan Manuel
Published: December 2012

We study the horizontal surface mixing and the transport induced by waves, using local Lyapunov exponents and high resolution data from numerical simulations of waves and currents. By choosing the proper spatial (temporal) parameters we compute the Finite Size and Finite Time Lyapunov exponents (FSLE and FTLE) focussing on the local stirring and diffusion inferred from the Lagrangian Coherent Structures (LCS). The methodology is tested by deploying a set of eight lagrangian drifters and studying the path followed against LCS derived under current field and waves and currents.