bluuebunny/crossref_metadata_2025 huggingface dataset:
BONDED POROUS REVETMENTS - EFFECT OF POROSITY ON WAVE-INDUCED LOADS AND HYDRAULIC PERFORMANCE
Authors: Liebisch Sven , Alcérreca Huerta Juan Carlos , Kortenhaus Andreas , Oumeraci Hocine
Published: December 2012

The porosity and roughness of bonded revetments are both crucial for the hydraulic performance and the wave loading of the revetment and its foundation, and thus for the stability and durability of the entire structure. This is briefly shown by the selected results of a tentative comparative analysis of two large-scale test series performed in the Large Wave Flume (GWK) Hanover with two significantly different revetments: a highly porous and rough polyurethane bonded aggregate (PBA) revetment and an almost impermeable and relatively smooth interlocked pattern placed block (IPPB) revetment. These results motivated the initiation of the three years research project BoPoRe (Bonded Porous Revetments) which has the primary objective to investigate more systematically and separately the relative importance of both porosity and roughness for different slope steepnesses. This project is briefly introduced and the first results of preliminary scale model tests using 9 configurations for the porosity and roughness of the revetment subject to a wide range of wave conditions (surf similarity parameters 0.93-7.21) are briefly discussed.
LIMITS OF THE NEW TRANSMISSION FORMULA FOR PI-TYPE FLOATING BREAKWATERS
Authors: Ruol Piero , Martinelli Luca , Pezzutto Paolo
Published: December 2012

The aim of this work is to assess, by means of available experimental results and numerical simulations, the possible extension of the range of application of the formula proposed by Ruol et al. (J. Wat. Port, Coast. Ocean Eng., 1, 2013), giving wave transmission for chain-moored ï-type floating breakwaters. The formula is here applied out of the range used for its calibration and even to other types of FBs. The error between predicted and measured values is described and discussed with reference to the main geometrical variables. It appears that the formula performs fairly well for the box-type FB, but not in cases characterized by very different mooring stiffness compared to the one used for calibration. For instance in case of fixed or tethered FBs, the formula significantly overestimates the wave transmission.
ANTIREFLECTIVE VERTICAL STRUCTURE EXTENDED FOR ATTENUATION OF LOW FREQUENCY WAVES
Authors: Gonzalez-Escriva Jose Alberto , MEDINA Josep Ramon
Published: December 2012

A new maritime vertical structure was designed to improve the antireflective performance for wave reflection of wind waves and oscillations associated with intense storms, resonance waves in port basins, etc. Multiple unit chambers formed with long cell circuits (Medina et al., 2010) are responsible for the low frequency wave absorption that was studied through large-scale model testing.
OPTIMIZATION OF THE WAVECAT WAVE ENERGY CONVERTER
Authors: Fernandez Hernan , Iglesias Gregorio , Carballo Rodrigo , Castro Alberte , Sánchez Marcos , Taveira-Pinto Francisco
Published: December 2012

The development of efficient, reliable Wave Energy Converters (WECs) is a prerequisite for wave energy to become a commercially viable energy source. Intensive research is currently under way on a number of WECs, among which WaveCat©-a new WEC recently patented by the University of Santiago de Compostela. In this sense, this paper describes the WaveCat concept and its ongoing development and optimization. WaveCat is a floating WEC intended for operation in intermediate water depths (50-100 m). Like a catamaran, it consists of two hulls-from which it derives its name. The difference with a conventional catamaran is that the hulls are not parallel but convergent; they are joined at the stern, forming a wedge in plan view. Physical model tests of a 1:30 model were conducted in a wave tank using both regular and irregular waves. In addition to the waves and overtopping rates, the model displacements were monitored using a non-intrusive system. The results of the physical model tests will be used to validate the 3D numerical model, which in turn will be used to optimize the design of WaveCat for best performance under a given set of wave conditions.
MODELING OF DAMAGE PROGRESSION OF RUBBLE MOUND REVETMENT AND APPLICATION TO PERFORMANCE EVALUATION
Authors: Ota Takao , Matsumi Yoshiharu , Kato Nobuaki , Ohno Ken-ichi
Published: December 2012

In this study, the modeling of damage progression of rubble mound revetment and the performance evaluation based on laboratory experiments and numerical computations are performed. The model profiles for the damaged revetment are made on the basis of the experiments to measure the profile change. The model profiles corresponding to the degree of damage are determined by using some empirical equations that are related to the deformation quantity of the revetment. To examine the change of performance due to damage progression, the model profiles are also used in other experiments and numerical computations. The reflection coefficient and overtopping rate are taken as performance indices. The measured reflection coefficient shows a tendency to decrease, while the overtopping rate increases more than twice as much as that of the initial profile with damage progression of the revetment. The computed reflection coefficient and overtopping rate agree reasonably well with the experimental data.
PREDICTION OF WAVE FORCE ACTING ON HORIZONTAL PLATE
Authors: Araki Susumu , Deguchi Ichiro
Published: December 2012

The applicability of the existing prediction methods of the wave force acting on a horizontal plate above the still water
level is investigated by comparing the estimated wave force with the measured wave force. The applicability of a
numerical model as well as the equations from experimental results is investigated. Some prediction methods overestimate the measured wave force, and some prediction methods underestimate the measured wave force.
HYDRAULIC STABILITY OF COASTAL STRUCTURES MADE OF GEOTEXTILE SAND CONTAINERS (GSCS): EFFECT OF ENGINEERING PROPERTIES OF GSCS
Authors: Dassanayake Darshana Tharindra , Oumeraci Hocine
Published: December 2012

Due to their numerous advantages, Geotextile Sand Containers (GSCs /or Geobags) are getting increasingly popular as an alternative to conventional hard (rock / concrete) structures. This study attempts to evaluate the significance of the most important engineering properties and their influence on the hydraulic stability of GSC-structures. The most important engineering properties of GSCs are the mechanical properties of the geotextile material, the sand fill ratio, type of the fill material, the interface friction, etc. In fact most of these properties will affect the deformation of GSCs and the movement of sand inside the container. More importantly, these properties are interrelated. The importance of these aspects has been highlighted in many studies and projects worldwide. However, the knowledge about the influence of the sand fill ratio, the properties of fill material and the interface friction of GSCs on the hydraulic stability of GSC-structure is still very poor. Therefore, a series of experimental investigations were conducted, in order to better understand their effect on the hydraulic stability and to develop a computational tool and simple formulae for the hydraulic stability of different types of GSC-structures subject to different wave conditions. This paper contains some selected findings from these experimental investigations, which were performed at Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI). Furthermore, the sensitivity of each GSC property on the hydraulic stability and new hydraulic stability nomograms are presented, including the implications for the engineering practice.
MODELLING WAVE-INDUCED RESIDUAL PORE PRESSURE AND DEFORMATION OF SAND FOUNDATIONS UNDERNEATH CAISSON BREAKWATERS
Authors: El Safti Hisham , Kudella Matthias , Oumeraci Hocine
Published: December 2012

A finite volume model is developed for modelling the behaviour of the seabed underneath monolithic breakwaters. The fully coupled and fully dynamic Biot's governing equations are solved in a segregated approach. Two simplifications to the governing equations are presented and tested: (i) the pore fluid acceleration is completely neglected (the u-p approximation) and (ii) only the convective part is neglected. It is found that neglecting the pore fluid convection does not reduce the computational time for the presented model. Verification of the model results with the analytical solution of the quasi-static equations is presented. A multi-yield surface plasticity model is implemented in the model to simulate the foundation behaviour under cyclic loads. Preliminary validation of the model with large-scale physical model data is presented.
RISK-BASED LIFE CYCLE MIM STRATEGY FOR COASTAL STRUCTURES - EFFECT OF PRE-EXISTING DAMAGES ON FAILURE PROBABILITY -
Authors: Horstmann Nannina , Hinze Kerstin , Schimmels Stefan , Oumeraci Hocine
Published: December 2012

A risk-based strategy for monitoring, inspection and maintenance (MIM) is described as a key component of an overall framework for life-cycle engineering and management. Its application for coastal structures is exemplarily outlined for sea/estuary dikes and harbor quay walls. The necessity of the incorporation of pre-existing damages into this strategy is exemplarily illustrated for quay walls, showing how this will affect the failure probability in comparison to a quay wall without any pre-existing damages.
RESEARCH ON STABILITY OF OPENING SECTION AT BAYMOUTH BREAKWATER
Authors: Sakunaka Junichiro , Ariakawa Taro
Published: December 2012

The baymouth breakwater is to protect the port area from tsunami. It narrows the bay mouth and prevents tsunami from flowing in the port area. A submerged breakwater is built at the central opening section of the baymouth breakwater (Tsunami breakwater) to close the bay mouth as much as possible. Because of narrowness, it is expected strong current is generated at the opening section of the breakwater when tsunami occurs. The purpose of this study is to examine the stability of the opening of the breakwater on the basis of the result of numerical wave tank. Thus, conducting the experiments of the stability of the opening of the breakwater in large flume confirms the validity of results of calculations.
HYDRODYNAMIC LOAD ON THE BUILDING CAUSED BY OVERTOPPING WAVES
Authors: Chen Xuexue , Hassan Wael , Uijttewaal Wim , Verwaest Toon , Verhagen Henk Jan , Suzuki Tomohiro , Jonkman Sebastiaan N
Published: December 2012

Wide crested dike can reduce the kinetic energy of the overtopping wave and make the overtopping wave to flow back to the seaside. If a coastal town were built on or near a dike, the overtopping wave running on the dike crest generates the force which can affect the buildings located in its path. However, quantifying the hydrodynamic load on the building caused by overtopping waves is not straightforward because little empirical formulas are given in literature for this kind of configuration. Therefore, physical scale model research was carried out. The purpose of this research is to come up with a relationship describing the force on a vertical wall exerted by the overtopping wave as a function of wave parameters and geometrical characteristics.
PLACEMENT OF CUBIPOD ARMOR UNITS IN SAN ANDRÉS BREAKWATER (PORT OF MALAGA, SPAIN)
Authors: Corredor Antonio , Santos Moisés , Gómez-Martín M. Esther , Medina Josep R.
Published: December 2012

Single- and double-layer Cubipod armors were considered in the preliminary design of the San Andrés breakwater (Port of Malaga, Spain). 2D and 3D hydraulic stability and overtopping tests for single- and double-layer Cubipod armors were carried out as well as realistic 3D placement tests using a small-scale crawler crane and pressure clamps. The low bearing capacity of the sea bottom and the uncertainty about breakwater settlements were the key factors to use the double-layer Cubipod armor in the final design. Optimum placement grids are different for straight trunk, curved trunk and roundhead designs; the dimensionless plan curvature is the key factor for optimum placement grids. The bottom Cubipod armor layer placed on 1-tonne quarrystone was better placed with lower porosity than the upper Cubipod layer placed on 6-tonne (2.6 m3) Cubipods. The on-going prototype placement method with a crawler crane and pressure clamps is similar to that used in the small-scale tests.
WAVE OVERTOPPING AT DYKES WITH TOPPED VERTICAL WALL - IMPACTS OF OBLIQUE WAVE ATTACK
Authors: Kerpen Nils B. , Schlurmann Torsten
Published: December 2012

Hydraulic model tests at a scale of 1:10 are carried out in a 40 m x 25 m wave basin with a state-of-the-art 3D wave generator in order to collect wave overtopping data at vertical walls and dykes with topped vertical walls. Wave conditions in the near field of the structures, velocities under waves and the mean overtopping discharge are measured. The experiments have been commissioned by the Lower Saxony Water Management, Coastal Defense and Nature Conservation Agency (NLWKN) with the purpose to deliver essential overtopping data for validation of numerical models. Two main geometries are analyzed - each for two specific wave spectra. Overtopping rates are investigated with respect to the remaining freeboard height Rc and the influence of oblique wave attack Î²{0°, 10°, 30°, 40°, 50°, 60°}. Results are compared with existing analytical approaches. As expected for this special geometrical coastal protection structure, it is examined that overtopping discharges increase with decreasing remaining freeboard. Intensity of the reduction is more dependent on the wave spectra than on the dyke geometry. Mean wave overtopping rate increases with decreasing relative water depth Hm0/d directly in front of the vertical wall. Furthermore, the mean wave overtopping rates decrease with an increasing angle of wave attack Î². The correlation between mean wave overtopping rate and freeboard height is given in four newly adapted design formulas, describing the overtopping performance of the two discussed dyke geometries with topped vertical walls.
FULL SCALE IMPACT TESTS OF AN OVERTOPPING BORE ON A VERTICAL WALL IN THE LARGE WAVE FLUME (GWK) IN HANNOVER
Authors: De Rouck Julien , Van Doorslaer Koen , Versluys Tom , Ramachandran Karunya , Schimmels Stefan , Kudella Matthias , Trouw Koen
Published: December 2012

To meet up with the requirements of the Flemish Government, the Belgian coastline needs a protection to a storm with a return period of 1000 years. At well-chosen locations, storm walls will be built, and for the structural design of these walls the impact loadings need to be known. Tests have been carried out at full scale in the Grosser Wellen Kanal, to determine the impact loads by overtopping bores. Wave overtopping over the crest of the dike occurs, and the overtopping bore progresses along the horizontal crest of the dike before impacting the storm wall. It is of major importance that such a wall can withstand the impacts. This paper describes the hydraulic process on the crest of the dike, expressed with parameters such as flow depth and flow velocity, and links them to the impact measured on the storm wall. Both pressures and forces are measured, and compared to each other.
SPATIAL DISTRIBUTION OF OVERTOPPING
Authors: Lioutas Anestis , Smith Gregory M. , Verhagen Henk Jan
Published: December 2012

The scope of this research is to find an empirical formula to describe the distribution of wave overtopping in the region behind the crest. A physical model was set up in which irregular waves were generated. In order to find a formula which adequately describes the test observations, the influence of several parameters has been analysed. The proper determination of the crest freeboard, which is a dominant factor, has been investigated. Finally, the test results have been used to assess and compare the existing relevant computational methods.
THE WAVE RUN-UP SIMULATOR, THEORY AND FIRST PILOT TEST
Authors: Van der Meer Jentsje , Provoost Yvo , Steendam Gosse Jan
Published: December 2012

The idea of the Wave Run-up Simulator is based on the experiences with the Wave Overtopping Simulator. It is possible to simulate wave tongues overtopping a dike crest in reality. It must also be possible to simulate waves in the run-up and run-down zone of the seaward slope. This is the zone after waves have broken and when they rush-up the slope. The present paper describes this new idea of the Wave Run-up Simulator, why it is useful to develop the machine, to perform research with it and to develop a prediction method for slope strength. In fact, a prediction method can already be developed from the Cumulative Overload Method, which was developed on the basis of results with the Wave Overtopping Simulator, see Van der Meer et al. (2010). It also means that tests on the seaward slope will be done for validation purposes only. The paper describes in detail what is known about the movement of waves in this run-up zone and what actually the Wave Run-up Simulator has to simulate. Not a lot of research has been performed to describe the wave run-up process in detail, physically nor statistically. Finally, the pilot test has been described including hydraulic measurements on the slope.
COUPLED FLUIDITY/Y3D TECHNOLOGY AND SIMULATION TOOLS FOR NUMERICAL BREAKWATER MODELLING
Authors: Xiang Jiansheng , Latham John-Paul , Vire Axelle , Anastasaki Elena , Pain Christopher C.
Published: December 2012

FEMDEM modelling which combines the multi-body particle interaction and motion modelling (i.e. Discrete Element Model, DEM) with the ability to model internal deformation of arbitrary shape (Finite Element Model, FEM) has been applied to breakwater models. There are two versions of a FEMDEM solver developed; Y3D_D is for deformable materials and is required for dynamic and static stress analysis and Y3D-R is the rigid version often used to numerically construct the armour unit packs. This paper also reports the placement protocols: POSITIT.
FEMDEM modelling deals with solids interactions and is one modelling component that is to be coupled to other modelling technologies e.g. CFD, interface tracking, wave models, porous media etc. so that the key fluid-solid interactions can be modelled in a full scale virtual breakwater alongside work on scaled hydraulic laboratory models and prototype structures. The latest developments of two-way coupled interactions of waves with coastal structures are also described in this paper.
DESIGN OF A 3D PHYSICAL AND NUMERICAL EXPERIMENT ON FLOATING OFF-SHORE WIND TURBINES
Authors: Tomasicchio Giuseppe Roberto , Armenio Elvira , D'Alessandro Felice , Fonseca Nuno , Mavrakos Spyros A. , Penchev Valery , Schuttrumpf Holger , Voutsinas Spyridon , Kirkegaard Jens , Jensen Palle M.
Published: December 2012

The knowledge of the behavior of floating offshore wind turbines (W/T) under wave and/or wind action remains one of the most difficult challenges in offshore engineering which is mostly due to the highly non-linear response of the structure. The present study describes the design process of a 3D physical experiment to investigate the behavior of the most promising structure technology of floating W/T: spar buoy (SB) and tension leg platform (TLP) under different meteo conditions. In order to properly design the two W/T models, the following topics have been analyzed: mooring lines, mass distribution, appropriate scaling factor and data relative to the geometrical characteristics, wave basin dimensions and wind and waves conditions. In addition, the Smoothed Particle Hydrodynamics method (SPH) (Monaghan 1994) has been considered to simulate the 3D behavior of a floating offshore W/T. In particular, the SPH, calibrated and verified on the basis of the experimental observations, may represent a reliable tool for preliminary test of changes in the floater geometry.
A FARM OF WAVE ACTIVATED BODIES FOR COASTAL PROTECTION PURPOSES
Authors: Angelelli Elisa , Zanuttigh Barbara
Published: December 2012

This paper aims at investigating the efficacy of a floating farm of wave energy converters for coastal protection purposes through physical and numerical modelling. The experiments were performed in 3D conditions on a basic module consisting of two staggered lines and three devices. The numerical simulations were carried out with the software MIKE 21 BW, developed by DHI Water & Environment & Health, and were calibrated based on the experimental results. Additional configurations were tested by varying the gap long-shore width and the device alignment. Despite the model limitations, i.e. the representation of the devices as fixed porous piles, the numerical results well approximate the average measured transmission coefficient and allow to derive a complete map of the hydrodynamics around the devices.
RECONNAISSANCE LEVEL STUDY MISSISSIPPI STORM SURGE BARRIER
Authors: Van Ledden Mathijs , Lansen Joost , De Ridder Hennes , Edge Billy
Published: December 2012

This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further increase the risk of flooding due to hurricane storm surge. A surge barrier downstream of New Orleans has been considered as an alternative to levee raise along the Mississippi River. Hydraulic computations show that the build-up of water behind the barrier due to the Mississippi

River flow is (much) lower than the hurricane surge protruding up the river in the no-barrier situation. The barrier will probably eliminate the need to upgrade the system upstream of the barrier while providing the same level of hurricane risk reduction. A hybrid barrier (a combination of different gate types) with a primary swing gate for navigation (and flow) and secondary lift gates to accommodate for flow is a technically feasible alternative. The barrier remains open for almost the entire year and would only to be closed during severe tropical events (say once every 2 - 3 years). Several measures are included in the conceptual design to mitigate the navigation impact. The construction costs of the barrier are estimated at $1.6 - 2.6 billion. It is recommended to compare the investment costs of a barrier including adjacent tie-ins to the existing HSDRRS to the costs of upgrading and maintaining the levee system throughout the city of New Orleans.
DISPLACEMENT OF MONOLITHIC RUBBLE-MOUND BREAKWATER CROWN-WALLS
Authors: N¸rgaard J¸rgen Quvang Harck , Andersen Lars Vabbersgaard , Andersen Thomas Lykke , Burcharth Hans F.
Published: December 2012

This paper evaluates the validity of a simple one-dimensional dynamic analysis as well as a Finite-Element model to determine the sliding of a rubble-mound breakwater crown-wall. The evaluation is based on a case example with real wave load time-series and displacements measured from two-dimensional physical model tests. The outcome is a more reliable evaluation of the applicability of simple dynamic calculations for the estimation of displacement of rubble-mound superstructures. The case example clearly demonstrates that a simplified one-dimensional sliding model provides a safe estimate of the accumulated sliding distance of crown-wall superstructures, which is in contrast to findings from previous similar studies on caisson breakwaters. The calculated sliding distance is approximately three times larger than the measured one when using the original one-dimensional model suggested in previous studies on caisson breakwaters, but correction terms are suggested in the present paper to obtain almost equal measured and estimated displacements. This is of great practical importance since many existing rubble-mound crown-walls are subjected to increasing wave loads due to rising sea water level from climate changes. Reliable and safe estimates are needed to determine whether displacements of crown wall superstructures during extreme situations would be acceptable or whether they lead to total failure of the structures.
INTEGRATED DESIGN OF COASTAL PROTECTION WORKS FOR WENDUINE, BELGIUM
Authors: Veale William , Suzuki Tomohiro , Verwaest Toon , Trouw Koen , Mertens Tina
Published: December 2012

Wave overtopping tests were performed with a 1:25 physical scale model to determine the optimal geometry for design of new wave return walls at Wenduine, Belgium. Wave overtopping on the shallow foreshore at Wenduine was found to be dominated by low-frequency infragravity waves (f < 0.04 Hz at prototype scale). Mean wave overtopping discharge measured with the physical model compared well with the Van Gent (1999) empirical overtopping equations for shallow foreshores. Physical model tests confirmed that the stilling wave basin concept proposed by Geerearts, et al. (2006) and wave wall parapet concepts of van Doorslaer & De Rouck (2010) were effective at reducing the wave wall height required to meet the tolerable discharge overtopping standards.
BREAKING WAVE KINEMATICS, LOCAL PRESSURES, AND FORCES ON A TRIPOD STRUCTURE
Authors: Hildebrandt Arndt , Schlurmann Torsten
Published: December 2012

This paper presents breaking wave loads on a tripod structure from physical model tests and numerical simulations. The large scale model tests (1:12) are described as well as the validation of the three dimensional numerical model by comparison of CFD wave gauge data and pressures with measurements in the large wave flume inside and outside the impact area. Subsequently, the impact areas due to a broken wave, a curled wave front as well as for wave breaking directly at the structure with a partly vertical wave front are compared to each other. Line forces in terms of slamming coefficients with variation in time and space are derived from CFD results and the velocity distribution is presented at the onset of wave breaking. Finally, the results are briefly discussed in comparison to other slamming studies.
VERIFICATION OF DESIGN LIFE EXPOSURE AND PERFORMANCE OF A BERM BREAKWATER
Authors: Todd David , Blanksby Amanda , Schepis John
Published: December 2012

A mass armoured berm breakwater design was developed for a deepwater port project, under a build, own, operate and transfer project delivery model. The need to confirm short term (10 year) and long term (100 year) breakwater reshaping performance lead to a detailed assessment of design life exposure over these durations, combined with an extended physical scale model testing program. The aim of this testing program was to simulate, as far as practical, the design life performance of the breakwater with respect to berm reshaping and recession performance.
WAVE RUN-UP OBSERVATIONS ON REVETMENTS WITH DIFFERENT POROSITIES
Authors: Schimmels Stefan , Vousdoukas Michalis , Wziatek Dagmara , Becker Katharina , Gier Fabian , Oumeraci Hocine
Published: December 2012

Wave run-up plays an important role in the design of coastal protection structures. However, none of the existing formulae for wave run-up predictions explicitly considers the effect of revetment porosity. Recently, two revetments have been tested in the Large Wave Flume (GWK) of Forschungszentrum Kuste (FZK), a new type of highly porous polyurethane bonded (PBA revetment) revetment and a smooth interlocked pattern placed concrete block revetment (IPPB revetment), which is considered as "weakly permeable† for the present study. Wave run-up is evaluated by video data analysis based on timestack image processing. The results derived from the timestacks are compared to run-up data measured with conventional wire gauges and the good agreement demonstrates the accuracy and reliability of the video data analysis. The effect of the porosity of the revetment is incorporated into the EuroTop wave run-up formula, showing that for the present case it may reduce the relative run-up heights Ru,2%/Hm0 by about 25 % to 50 % as compared to a smooth impermeable slope.
DISTRIBUTION OF IMPACT INDUCED PRESSURES AT THE FACE OF UNIFORMLY SLOPED SEA DIKES: PRELIMINARY 2D EXPERIMENTAL RESULTS
Authors: Stagonas Dimitris , Muller Gerald , Ramachandran Karunya , Schimmels Stefan , Dane Alec
Published: December 2012

Although existing knowledge on the vertical distribution of impact pressures on sea-dikes is well established only very little is known with respect to their horizontal distribution. A collaboration developed between the University of Southampton, Uk and FZK, Hannover looks in more detail at the distribution of pressures induced by waves breaking on the face of a sea-dike. For this, 2D large scale experiments with waves breaking on a 1:3 sea dike were conducted but instead of pressure transducers a tactile pressure sensor was used to map the impact pressures. Such sensors were initially used with breaking waves in the University of Southampton and their use for large scale experiments was attempted here for the first time. In the current paper the calibration and application of the tactile sensor for experiments involving up to 1m high and 8sec long waves are initially described. Preliminary results illustrating the simultaneous distribution of impact induced pressures over an area of 426.7x487.7mm are then presented. Based on these pressure maps the vertical and horizontal location of maximum breaking wave induced pressures is also deduced.
AN UNIFIED DESIGN METHOD OF MARITIME WORKS AGAINST WAVES
Authors: Clavero María , Vílchez Montserrat , Pérez Dulce , Benedicto María Izaskun , Losada Miguel Angel
Published: December 2012

This work studies the interaction of a composite breakwater and irregular waves as a function of the breakwater geometry and wave characteristics. For this, tests in a flume wave were carried out. The model consisted of a composite breakwater with rectangular cross section and with the width, foundation depth and stone diameter varying in order to know their influence in the breakwater behavior. Results show that reflection coefficient increase with B/L (where B is the width of the dike and L is the wave length) until a maximum value (saturation point) from which it is constant or decreases slightly. Before this point, reflection coefficient depends on breakwater geometry and wave characteristics and when the dike reaches the saturation regime, it only depends on stone diameter or porosity. The value of the sea water elevation at the wall and the horizontal pressure depends on the reflection coefficient. Finally, the relationship between horizontal and vertical forces is linear depending on the reflection regime. This analysis shows that energy distribution is the main variable to know the structural behavior of a dike. Based on these results, a methodology to obtain the loads over the composite breakwater is proposed.
PHYSICAL MODELING OF SAND LIQUEFACTION UNDER WAVE BREAKING ON A VERTICAL WALL
Authors: Michallet Hervé , Rameliarison Valerie , Berni Celine , Bergonzoli Maxime , Barnoud Jean-Marc , Barthelemy Eric
Published: December 2012

The wave induced liquefaction at a coastal structure is studied. Experiments in a glass-wall flume filled with a partially saturated bed of light-weight sediment are presented. Single wave loadings are simulated. For large enough wave height conditions an excess pore pressure is recorded within the soil and a liquefaction threshold is reached. Velocity fields obtained from video recordings display large zones of the bed that behave as a fluid. Phases of soil compaction and dilatancy are identified.
COMBINED PHYSICAL AND NUMERICAL MODELLING TO INFORM OPTIMAL MARINA DESIGN
Authors: Albanese Vincenzo , Powell Keith , Cuomo Giovanni
Published: December 2012

A new Marina, capable of hosting up to 1,000 boats, is being constructed along the southern Tyrrhenian Sea coast of Italy. The Marina is separated from the shore by a 80 m wide channel and access to the harbour will be via a bridge designed by Santiago Calatrava. Design improvements and refinements were identified through physical and numerical model studies. This paper shows the important role of numerical and physical models in the design process of a marina. For this project the physical model study has confirmed the effectiveness of the optimised design
RUBBLE MOUND BREAKWATER OVERTOPPING: ESTIMATION OF THE RELIABILITY OF A 3D NUMERICAL SIMULATION
Authors: Cavallaro Luca , Dentale Fabio , Donnarumma Giovanna , Foti Enrico , Musumeci Rosaria E. , Carratelli Eugenio Pugliese
Published: December 2012

Until recently, physical models were the only way to investigate into the details of breakwaters behavior under wave attack. From the numerical point of view, the complexity of the fluid dynamic processes involved has so far hindered the direct application of Navier-Stokes equations within the armour blocks, due to the complex geometry and the presence of strongly non stationary flows, free boundaries and turbulence. In the present work the most recent CFD technology is used to provide a new and more reliable approach to the design analysis of breakwaters, especially in connection with run-up and overtopping. The solid structure is simulated within the numerical domain by overlapping individual virtual elements to form the empty spaces delimited by the blocks. Thus, by defining a fine computational grid, an adequate number of nodes is located within the interstices and a complete solution of the full hydrodynamic equations is carried out. In the work presented here the numerical simulations are carried out by integrating the three-dimensional Reynolds Average Navier-Stokes Equations coupled with the RNG turbulence model and a Volume of Fluid Method used to handle the dynamics of the free surface. The aim of the present work is to investigate the reliability of this approach as a design tool. Two different breakwaters are considered, both located in Southern Sicily: one a typical quarry stone breakwater, another a more complex design incorporating a spill basin and an armoured layer made up by Coreloc® blocks.
NUMERICAL ANALYSIS OF WAVE AND NEARSHORE CURRENT FIELDS AROUND LOW-CRESTED PERMEABLE DETACHED BREAKWATERS
Authors: Nishihata Takeshi , Tajima Yoshimitsu , Sato Shinji
Published: December 2012

A Boussinesq type numerical model was developed which can simulate both wave fields and current fields around permeable detached breakwaters. The validity of the model was verified through measurements of waves and nearshore currents in hydraulic experiments investigating reflection and transmission capability. The porosity of the structure was accounted by a friction term incorporating turbulent resistance. The combination of turbulent friction model and anisotropic diffusion type wave breaking model was found to reproduce wave fields around the detached breakwaters and nearshore current fields behind the structures with a good accuracy.
NUMERICAL INVESTIGATION OF PRESSURE ACTING ON FLOATING PANEL FOR WAVE OVERTOPPING REDUCTION UNDER REGULAR WAVE ACTION
Authors: Kawasaki Koji , Dinh Han Ut , Matsuno Tetsuya , Fukumoto Tadashi
Published: December 2012

In this paper, a 3-D multiphase flow model with solid-gas-liquid interaction, named 'DOLPHIN-3D', is utilized to numerically investigate the characteristics of pressure acting on a floating panel, which is installed in front of an upright seawall for wave overtopping reduction. The validity and utility of the model were confirmed through good agreements between the numerical results and experimental ones in terms of the dynamic response of the floating panel and the pressure at the bottom of the panel. The numerical results revealed that the model can appropriately simulate the pressure acting on the floating panel as well as the dynamic behavior of the panel under wave action.
ASSESSMENT OF COASTAL FLOODING AT SOUTHERN MEDITERRANEAN WITH GLOBAL OUTLOOK FOR LOWLAND COASTAL ZONES
Authors: Ismail Nabil , Iskander Moheb , El-Sayed Walid
Published: December 2012

This paper presents an assessment of the performance of a shoreline revetment; M. Ali Seawall, placed to protect the land behind against flooding and overtopping at coastal site, within Abu Qir Bay, East of Alexandria along the Nile Delta coast. Coastal zone management of the bay coastline is of utmost significance to the protection of the low agricultural land and the industrial complex located in the rear side of the seawall under the current and progressive effects of climate change. The latest storm in December 2010, which hit the Nile Delta and which was the severest in the last decades showed that generated surges, up to 1.0 m as well as a maximum of 7.5 m wave height in the offshore of Alexandria presented a major natural hazard in coastal zones in terms of wave run up and overtopping. The storm, fortunately, resulted in a partial and modest flooding of the zone behind the seawall particularly in the beach segment, located in the middle of the seawall. This research project aims to the design review of the seawall which was first constructed in 1830 to protect the lowland agricultural area, 2.0 m below mean sea level, and was rehabilitated in 1981 as part of the Master Plan of the Nile Delta Coastal Zone Management. The seawall was further upgraded in 2009; one year before the 2010 storm. The paper will give an overview of the seawall design and its upgrades and the current conducted hydrodynamic analyses to estimate wave height distributions, wave run up and overtopping over the seawall and its beach segment. Use has been made of the in-house modified ImSedTran-2D model as well as universal design standards as EurOtop (2008). Based on the results for worst design scenarios, recommendations are given to increase the height of the seawall cap, to strengthen the beach top and back slope with a facility to drain storm water to increase coastal resilience behind the seawall. Comparison of the predicted overtopping with the observed wave overtopping volumes during the 8hrs-2010 storm, allowed the verification of the used universal design tools. Impact of precise estimate of storm and barometric surge as well as seawall armor roughness and shapes on overtopping rates are highlighted.
NOTIONAL PERMEABILITY
Authors: Kik Rémon , Van den Bos Jeroen P. , Maertens Jonas , Verhagen Henk Jan , Van der Meer Jentsje W.
Published: December 2012

Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath the armour layer has the ability to dissipate more wave energy and therefore requires less weight of the armour layer. The influence of this parameter is thus very important in economic sense. Up until now only three configurations have been tested. In practice often intermediate structures were designed which do not correspond to the standard situations. P-values then have to be estimated in comparison with the known structures, which gives some uncertainty around the P-value. Therefore there is the demand for more validated values of the notional permeability representing other structures. During this study physical scale modelling is used to produce a value of P for a new structure.
STABILITY OF RUBBLE MOUND BREAKWATERS IN SHALLOW WATER AND SURF ZONE : AN EXPERIMENTAL STUDY
Authors: Prevot Guirec , Boucher Olivier , Luck Maryline , Benoit Michel
Published: December 2012

Rubble-mound breakwaters are often pre-designed with empirical formulae allowing the estimation of armour stone size or weight, taking into account the wave conditions (mainly a characteristic wave height and a characteristic period), the type and density of stone or block used, the slope of the mound, the acceptable level of damage, etc. In deep water conditions, the existing formulas are rather well established (e.g. Hudson and Van der Meer formulas

among others). They use as input data wave parameters that are well defined (e.g. the significant wave height H1/3 or sometimes the height H1/10) and easily accessible, from in situ measurements or from numerical wave models. In shallow water however, and in particular in breaking wave conditions (where most of the small breakwaters are built), a number of physical processes (refraction, shoaling and breaking) significantly modify the incoming waves.

They also lead to changes in the wave height distribution (which can no longer be regarded as being of Rayleightype) and in the shape of the wave spectrum. This, combined with the fact that most of the models used nowadays for nearshore wave propagation are spectral wave models (e.g. SWAN, TOMAWAC, etc.) and thus provide spectral parameters as output (typically the spectral significant wave height Hm0 and the peak period Tp or the mean energetic

period Tm-1,0) has raised the question of which characteristic wave parameter should be used in stability formulas for rubble-mound breakwaters in shallow water. This has led to the consideration of more representative wave parameters such as H2% or Tm-1,0 which are sometimes less accessible from existing wave database or numerical modelling studies. The objective of the present study is to review and compare several available methods to calculate armour stone weight in shallow waters, and to provide some insight into the applicability and limitations of these methods based on a series of wave flume experiments.
DOWNFLOW BAFFLE BREAKWATERS LATEST DEVELOPMENTS AND LESSONS LEARNED
Authors: Frese Marianne , Bleck Matthias , Schöner Michael
Published: December 2012

Downflow baffle breakwaters or floating breakwaters are not as common as "full-depth" breakwaters. As a consequence the scientific work on hydraulic performance and loading is limited and most work dates back to the 1960s and 1970s. Several baffle breakwaters were planned and constructed in Germany in the last decades. Their advantages are reduced costs due to less material required and less impact on sediment transport and water quality. Experiences from different case studies and first results of a desk study on hydraulic performance and hydraulic loading will be described.
THE QUASI-STREAMFUNCTION FORMALISM
Authors: Tian Miao , Cottrell William , Sheremet Alex , Smith Jane
Published: December 2012

This paper provides a review of our recent developments in reformulating the quasi streamfunction (Î¨) formalism proposed by Kim et al. (2001) to relax the common constraint of kinematic bottom boundary condition. A restricted form of the Hamilton's principle for irrotational flows is formulated only on surface variables. This transforms the problem to dynamical equations on the surface and a constraint equation related to the interior water column. The interior solution can be applied to express Î¨ in terms of the natural canonically conjugate variable. The modified Î¨-formalism promises to provide a natural framework for the study of wave over arbitrary bathymetry and in the presence of strong shear flow if Clebsch variables are included. We demonstrate the formalism for horizontally homogeneous flows over mild topography, where asymptotic formulations for the Hamiltonian and Lagrangian are derived. The Hamiltonian shows consistency with Zakharov's results up to the cubic order and the Lagrangian is written in terms of measurable variables.
LONG WAVE EFFECTS ON BREAKING WAVES OVER FRINGING REEFS
Authors: Goertz John T. , Kaihatu James M. , Sheremet Alex , Smith Ernest R. , Smith Jane M.
Published: December 2012

Modeling of wave energy transformation and breaking on fringing reefs is inherently difficult due to their unique topography. Prior methods of determining dissipation are based on empirical data from gently sloping beaches and offer only bulk energy dissipation estimates over the entire spectrum. Methods for deducing a frequency dependent dissipation have been limited to hypothesized linkages between dissipation and wave shape in the surf, and have used bulk dissipation models as a constraint on the overall dissipation for mild sloping beaches. However, there is no clear indication that the constraint on the overall level of dissipation is suitable for the entire reef structure. Using these constraints the frequency dependent dissipation rate can be deduced from laboratory data, taken at the Coastal and Hydraulics Laboratory, of wave transformation over reefs. The frequency dependent dissipation rate can then be integrated over the spectrum to derive an empirically-based counterpart to energy flux dissipation. Comparing the bulk energy dissipation estimates for the reef system to the frequency based method allows for the modification of wave breaking parameters in the frequency estimation, to better estimate total dissipation. Since this method is based on the Fourier transform of the time series data, it allows the dissipation to be found as a function of the frequency. This analysis shows that there is a correlation between the amount of energy in the low frequencies of the wave spectrum and certain characteristics of the frequency dependent dissipation coefficient.
SECONDARY WAVES IN COASTAL ZONE: PHYSICAL MECHANISMS OF FORMATION AND POSSIBLE APPLICATION FOR COASTAL PROTECTION
Authors: Kuznetsov Sergey , Saprykina Yana
Published: December 2012

The formation of secondary wave in a coastal zone was investigated on the base of field, laboratory and numerical experiments. It was found that formation of secondary waves is essentially part of weakly nonlinear-dispersive wave transformation and determined by a periodic exchange of energy between the first and second harmonics. The formation of secondary waves depends on a stage of wave transformation and defined by amplitude of secondary harmonic and by phase shift between first and second harmonics. On the base of numerical modeling and laboratory experiments an idea of combination of underwater structures with floating breakwater is investigated. Waves propagating above submerged bar generate secondary waves that decrease the mean period of waves. Each additional bar reinforces and stabilizes this effect. Behind the bars the floating breakwater can be applied, because it suppresses successfully only short waves. Advantages and disadvantages of this idea are discussed.
ON THE PROBABILITY DISTRIBUTION OF FREAK WAVES IN FINITE WATER DEPTH
Authors: Ahn Kyungmo , Kim Sun-Kyung , Cheon Se-Hyun
Published: December 2012

This paper presents the occurrence probability of freak waves based on the analysis of extensive wave data collected during ARSLOE project. It is suggested to use the probability distribution of extreme waves heights as a possible means of defining the freak wave criteria instead of conventional definition which is the wave height greater than the twice of the significant wave height. Analysis of wave data provided such finding as 1) threshold tolerance of 0.2 m is recommended for the discrimination of the false wave height due to noise, 2) no supportive evidence on the linear relationship between the occurrence probability of freak waves and the kurtosis of surface elevation 3) nonlinear wave-wave interactions is not thh primary cause of the generation of freak waves 4) the occurrence of freak waves does not depend on the wave period 5) probability density function of extreme waves can be used to predict the occurrence probability of freak waves. Three different distribution functions of extreme wave height by Rayleigh, Ahn, and Mori were compared for the analysis of freak waves.
WAVE HEIGHT DISTRIBUTION IN CONSTANT AND FINITE DEPTHS
Authors: Caires Sofia , Van Gent Marcel R.A.
Published: December 2012

Several alternatives to the Rayleigh distribution have been proposed for describing individual wave heights in regions where depth-induced wave breaking occurs. The most widely used of these is the so-called Battjes and Groenendijk distribution. This distribution has been derived and validated in a context of a shallow water foreshore waves propagating over a gently sloping shallow region towards the shore. Its validity for waves propagating in regions with
shallow flat bottoms is investigated here. It is concluded that the distribution on average underestimates (outside its range of validity) high wave height measurements in shallow flat bottoms by as much as 15%.