Type Of Breakwater Research Articles

Oblique Wave Scattering by a Pair of Asymmetric Inverse Π-Shaped Breakwater

Abstract The topic of wave scattering by different breakwaters has unfolded over the past few decades, largely driven by the profound impacts of global climate change. In this study, a completely new type of breakwater, inverse Π-shaped breakwater, has been taken into account for serving both purposes from analytical as well as an application point of view. During the formulation, the actual physical problem is transferred into a boundary value problem by employing the small amplitude water wave theory. With the aid of eigenfunction expansion, the problem is reduced to a set of integral equations having square-root singularities at the submerged edges of thin structures. To address such singularities, a multi-term Galerkin approximation technique is used along with Chebyshev polynomials (multiplied with suitable weights) as basis functions. The numerical methodology employed here validates with different previous literatures as special cases. Then, numerical solutions of the reflection and transmission coefficients, hydrodynamic forces are graphically illustrated across various dimensionless structural parameters. In summary, the present paper offers valuable insights into the dynamics of wave scattering by a pair of asymmetric inverse bottom-mounted Π-shaped breakwater, emphasizing the role of different non-dimensional parameters in this system.

Empirical Predictions on Wave Overtopping for Overtopping Wave Energy Converters: A Systematic Review

Over the past three decades, the development and testing of various overtopping wave energy converters (OWECs) have highlighted the importance of accurate wave run-up and overtopping predictions on those devices. This study systematically reviews the empirical formulas traditionally used for predicting overtopping across different types of breakwaters by assessing their strengths, limitations, and applicability to OWECs. This provides a foundation for future research and development in OWECs. Key findings reveal that empirical formulas for conventional breakwaters can be categorized as mild or steep slopes and vertical structures based on the angle of the slope. For the same relative crest freeboards, the dimensionless average overtopping discharge of mild slopes is larger than that of vertical structures. However, the formula features predictions within a similar range for small relative crest freeboards. The empirical formulas for predicting overtopping in fixed and floating OWECs are modified from the predictors developed for conventional breakwaters with smooth, impermeable and linear slopes. Different correction coefficients are introduced to account for the effects of limited draft, inclination angle, and low relative freeboard. The empirical models for floating OWECs, particularly the Wave Dragon model, have been refined through prototype testing to account for the unique 3D structural reflector’s influence and dynamic wave interactions.

Simulation of the effects of pile-rock breakwaters on the coastal sediment transport at Ganh-Hao beach, Bac-Lieu province, Vietnam

Abstract In recent years, the flat riverside coastal area of the Mekong Delta has been dealing with complex issues related to erosion and the buildup of sediment. Numerous research efforts have been undertaken to propose ways to address the adverse effects of shoreline erosion. One of these proposed solutions involves the construction of various types of breakwaters. A contemporary approach includes a design featuring concrete piles combined with a rock core, which has shown promising initial results in reducing wave impact and promoting sediment accumulation behind the structure. This study adopts a quantitative approach to examine how this structure influences sedimentation and erosion processes, the movement of suspended sandy sediments, and the seafloor within the zone extending from the structure to the shore. The research team utilized the Telemac numerical model, which combines dynamic hydrological calculations with simulations of coastal waves and sediment transport. The simulation results indicate a noticeable reduction in the concentration of suspended sandy sediments and an enhancement in sediment deposition in the area behind the coastal structure.

Experimental Study of the Relationship between Slope and Opening Height of OWC Type Wave Breaker Model on Wave Reflection

Breakwater is a very effective wave dampening building to be used as a coastal protection against coastal abrasion by destroying wave energy before it reaches the coast. The working mechanism of the OWC type is the rise and fall of ocean waves which will push the air in the OWC column, then will rotate the turbine connected to the generator to produce electricity. This study aims to determine the effect of slope and opening height on breakwater on wave reflection. Then analyze the parameters that affect the amount of wave reflection and compare the resulting wave parameters. This research was conducted at the Hydraulics Laboratory, Department of Civil Engineering, Faculty of Engineering, Hasanuddin University. The method used was experimental based. The resulting wave characteristics consist of three depth variations, three period variations and three stroke variations. The research model used is an Oscillating Water Column (OWC) type breakwater with slope variations of 45°, 60° and 90° and open wall variations as high as 5 cm, 10 cm and 15 cm. The reading of the water level fluctuation is done electronically through the reading of the wave monitor. The results showed that the magnitude of the reflection coefficient is influenced by structural parameters, namely the slope and height of the model opening and hydraulic parameters, namely depth, period and wave height. The effect of the model slope on the reflection coefficient is that the greater the slope, the greater the reflection coefficient value. The effect of the model opening height is that the greater the opening height, the smaller the reflection coefficient value.

On the study of a body force model for a jetting type breakwater

The introduction of jetting-type floating breakwaters can significantly enhance the performance of large floating marine structures. Especially, this novel technology may effectively handle traditional breakwaters' bottleneck, namely, weak wave dissipation performance under large period waves. In this paper, a new method is established using body force model, in conjunction with a computational fluid dynamics solver and dynamic overlapping mesh technology, to simulate jetting-type floating breakwaters. The mathematical model is elucidated in the context of fluid mechanics, propellers body force model, and floating breakwaters’ geometric aspects. The method is proved to be compact and flexible in terms of implementation, offering advantages for the simulation of floating breakwaters employing hydraulic systems. Moreover, the new method can resolve low efficiency during computation, normally caused by fine local flows when simulating long-range jetting-type floating breakwaters: By controlling parameters precisely, it simulates accelerating local flows, high-speed water-jets, and it offers efficient visualization of the water-jets and their effects on floating breakwaters. Results show that the novel jetting-type floating breakwater significantly enhances wave dissipation. A comparison is performed between the novel breakwater against the typical example of square box floating breakwater with same dimensions and under wave incidence, thus the accuracy of the method was verified likewise. This research provides a new numerical method for jetting technologies applied to floating breakwaters and porous structures, also offering valuable insights for new types of wave dissipation methods.

Evaluasi Bangunan Pelindung Pantai Sisi Miring Dalam Upaya Penanggulangan Abrasi Pesisir Pantai

The coast of Kampung Jawa Lama, Banda Sakti Sub-district, Lhokseumawe City is a fishing area and densely populated. The breakwater building in the coastal area of Kampung Jawa Lama is a sloping Breakwater with a height of 1.5 m and a width of 1 m. The type of breakwater used is usually determinet by the availability of material on the site. The problem in this research was the cause of abrasion and its impact, as well as how to plant coastal protection structures. The purpose of this study was to reduce the impact of erosion, abrasion and damage to the buildings and to re-evaluate coastal structures. The method used on this research is Hudson method and descriptive analysis by making direct observation and reviuwing research that has been done previously. The cause of abrasion is triggered by several factors such us tides, high sea waves and ocean currents that have the potential to cause damage as a result of strong winds that produce destructive waves. The community also receiver the impact of the abrasion, namely decreasing income, the place where they live is inundated by sea water and it affects the decline in the quality of life of the community. One of the efforts that can be applied to reduce the abrasion problem in the area is to build a Breakwater construction. Based on calculation, the results obtained in the planning reviuw of the existing shoreline protection building were 1.5 m, so that to prevent abrasion the increase in height of the building 4.074 m was 5.574 m with a peak width of 1 m so that increase of 0.20 m was 1.2 m, the thickness of the first layer of protection was 1.2 m and the thickness of the second layer was 0.60 m. The width of the leg guard is 1.8 m with a thickness of 0.5 m

Numerical investigation on the hydrodynamic and conversion performance of a dual cylindrical OWC integrated into a caisson-type breakwater

The hydrodynamic performance of an integrated oscillating water column (OWC) combined with a cylindrical caisson type breakwater was investigated. A three-dimensional numerical wave tank was established to simulate the overall energy conversion performance and hydrodynamics of the integrated system with the software Star-CCM+. The developed Computational Fluid Dynamics (CFD) model was initially verified with the published physical results and numerical results derived from an analytical solution. The effects of the structural geometry and the pneumatic damping of the PTO system on the wave absorption and power conversion efficiency of the proposed device were investigated using this developed model. Based on this proposed numerical model, the velocity of the air flow, the corresponding air pressure characteristics in the air turbine nozzle and chamber zone were discussed. The results indicate that this proposed half-open land based OWC is adapted to absorb shorter nearshore waves, characterized by dimensionless wave number kd approaching 1.49. Furthermore, a larger opening inlet zone for this proposed OWC would shift the resonant corresponding kd to higher wave frequencies, while lowering the opening inlet could help to increase the power extraction efficiency for long waves. The peak hydrodynamic efficiency is observed at a ratio of OWC inlet width to diameter B/D of 0.97, which is approximately six times larger than that at B/D = 0.5. The inclusion of an impulse turbine yields a more uniform pressure distribution within the central chamber and effectively mitigates wave reflection for smaller incident waves, with maximum efficiency achieved using 37 blades. The property of the efficiency mitigation with insufficient certain intake depth of the wave chamber should be avoided for system design.

Numerical simulation study of wave dissipation performance of step‐type breakwaters

AbstractTo improve the force endurance capacity of plate breakwaters, a step‐type plate breakwater was proposed. The performance of the step‐type breakwater was investigated by numerical simulation method. First, a two‐dimensional numerical regular wave tank was constructed using FLUENT software, and the effectiveness of the tank application was verified by comparing with theoretical value and test data. Then, the numerical tank was used to simulate various working conditions, and the variation rules of the breakwater transmission coefficient with wave height, period, perforation rate, relative plate width, wave steepness, and number of layers were obtained. Finally, the difference in the wave dissipation mechanism between the step‐type breakwater and the “”‐type breakwater was discussed. The results indicated that the transmission coefficient of the step‐type breakwater was small, which also proved to be good at dissipating long‐period waves. In general, the wave dissipation performance of the step‐type breakwater was better than that of the “”‐type breakwater. The research can provide some clues for the research and design of corresponding breakwaters.

An experimental study on the hydrodynamic performance of the underflow breakwater with two unequal baffles

In our previous paper (Li et al., 2022), the hydrodynamic characteristics of the underflow breakwater with two identical baffles were experimentally studied. In this work, the properties of an underflow breakwater with two unequal baffles on the front and back sides is investigated with respect to the hydrodynamic characteristics of this type of breakwater. Different parameters, including the relative blockage of front baffle, breakwater width, relative water depth, and two water surface states between two baffles, is considered under the regular and irregular waves. First, the resonance phenomenon is analyzed under the regular wave conditions. It has been observed that the resonance period is influenced by the width of the breakwater and the minimum relative blockage between the two baffles. The resonance has significant influence on the hydrodynamics of the breakwater characteristics. Thereafter, the transmission coefficient and reflection coefficient are studied. The transfer function of the breakwater under irregular wave is calculated. The transfer functions of different frequency spectrums are nearly identical and coincide with the transmission coefficients under regular waves. The results also indicate that this type of breakwater provides a better protection against short-period waves, whereas its effectiveness in the protecting against long-period waves is relatively weak. The results can be employed as a reference for practical engineering.

Experimental Study on Hydrodynamic Characteristics of Barge-Type Breakwaters under Different Mooring Methods

In this paper, a yacht project in Tingjiang Town, Mawei, Fujian, is suggested as an example of a barge type breakwater made out of scrap barges. The physical modelling of a two-dimensional flume wave test was carried out on a barge-type breakwater, focusing on the wave dissipation and anchor chain forces under two different mooring methods, the “crossed tilt” mooring and the “front and rear direct pull” mooring, with no change in the size of the breakwater. The test results show that the effect of wave elimination of the barge-type breakwater gradually decreases with the increase of wave elements under different mooring conditions, but the effect of wave elimination of the barge-type breakwater is significantly better under the “crossed tilt” mooring systems than under the “front and rear direct pull” mooring systems; the maximum tension of the anchor chain under the “inner eight” diagonal mooring method is significantly higher than that under the front and rear straight pulling mooring method. The maximum anchor chain tension under the “crossed tilt” mooring system is significantly greater than that under the fore and aft straight mooring method, while the average anchor chain tension does not change significantly under the two mooring methods.

Effect of data normalisation in estimating wave overtopping discharge parameter of semicircular breakwater using ANN and Random Forest.

Breakwaters are the structures constructed in the coastal areas to maintain calm inside the port or prevent beach erosion. Semi-circular Breakwater (SCB) is an innovative type of Breakwater made of hollow caisson on a base slab with or without perforations. In this study, the wave overtopping discharge parameter of an SCB is estimated using Artificial Neural Network and Random Forest. The data is collected and used in the current research from an experimental investigation conducted in the Wave Mechanics Laboratory of the Department of Water Resources and Ocean Engineering (WROE), NITK Surathkal. Using this experimental data, the ANN and Random Forest models are developed for the prediction of the wave overtopping discharge parameter of an SCB. The performance of the models is evaluated using different statistical parameters. Data with and without normalisation are used separately to check the effect of normalisation in the prediction of wave overtopping discharge parameter using ANN and Random Forest. From the results, it is found that ANN gives better results when the data is normalised. The performance of Random Forest is independent of the data normalisation.

Research Progress and Prospect of Wave Attenuation Performance and Integration of Wave-Energy Converter of Floating Breakwater

A floating breakwater can significantly reduce the wave invasion of marine structures and provide a safe construction environment and service environment for wave attenuation protection for marine structures. With the development and utilization of marine resources, the application of floating breakwaters in engineering is becoming more and more important; research on integrated systems of a floating breakwater and wave-energy converter (WEC) is also valuable. However, existing research has not yet systematically improved the influencing factors of wave attenuation performance of floating breakwaters and the summary of the wave attenuation mechanism; there are few summaries about the integration of floating breakwaters and wave-energy converters. Therefore, the research progress on the wave attenuation performance and wave-energy integration of floating breakwaters is reviewed and summarized. Firstly, according to the structural shape, floating breakwaters are divided into three types: box type, floating cylinder type, and other types. Secondly, the wave attenuation performance of three types of breakwaters and the research progress of floating breakwater-WEC integrated devices are discussed and reviewed. Finally, the problems to be solved in the study of various breakwaters and the key directions for future research are summarized. This review is helpful to deepen the cognition and understanding of wave attenuation performance of floating breakwater and floating breakwater-WEC integration devices, which can provide reference for the optimization research and engineering application of floating breakwaters.

A Laboratory Scale of the Physical Model for Inclined and Porous Breakwaters on the Coastline of Soc Trang Province (Mekong Delta)

In the last few decades, the Mekong Delta coastlines have suffered serious erosion. Strong waves during the Northeast Monsoon are one of the main reasons for this. Many types of breakwaters with different structural components have been designed and built to mitigate coastline erosion. Vertical seawalls have been widely used, but they create reflection waves, which can generate water particle kinematics in front of the structure and increase the toe scour. In this study, an innovative block of inclined and porous breakwaters was studied by conducting laboratory-scale experiments. The experimental results show that inclined and porous breakwaters can considerably reduce wave energy due to transmission, reflection, and diffraction compared to inclined breakwaters. The porosity on the front and back sides of the structures has also been studied. Letting sediment-laden seawaters penetrate inside the sheltered zones, porous breakwaters promote accretion and facilitate the forestation of mangrove belts.

Oblique wave trapping by a permeable wall breakwater connected with thick surface porous layer

ABSTRACT The reflection of surface gravity waves by a vertical wall breakwater connected with a thick surface porous layer is analysed under the framework of potential flow theory. The thick surface porous layer is placed within the confined space available between the vertical permeable wall and the impermeable seawall. The analytical investigation is progressed by creating the hidden water chamber beneath the surface porous layer. The Matched Eigenfunction Expansion Method (MEEM) is used based on the continuity of velocity and pressure along with orthogonal mode-coupling relation. The hidden water chamber will be helpful to enhance the trapping of incident wave energy and also to reduce the quantity of construction material. The present study results are well agreed with the results available in the literature when a hidden water chamber is absent. The effect of permeable wall porosity, thick surface layer porosity, angle of wave contact, depth of the surface porous layer, thickness of the permeable wall, and hidden chamber spacing on wave reflection against incident wave properties and breakwater physical properties are studied. A comparative study is performed between three different types of porous breakwaters to investigate the integrity of the proposed breakwater. The minor value of wave reflection and gradual reduction of fluid force experienced by the rigid wall is achieved due to the presence of a surface layer, which maximises the incident wave damping, as most of the wave energy propagates near the free surface.

Numerical Study on the Effects of the Multiple Porous Medium Breakwaters on the Propagation of the Solitary Wave

Submerged breakwater, as an important marine engineering structure, can effectively absorb wave energy and is widely used in marine engineering protection. As a new type of breakwater, porous medium breakwater has a certain influence on wave propagation. However, the influence of multiple porous medium submerged breakwaters on extreme waves remains to be studied. In the study, considering effects of extreme waves generated by hurricanes or tsunamis, the influence of the solitary wave on the multiple semi-circle porous medium breakwater is systematically investigated. According to the computational fluid dynamics theory, a numerical tank is established, in which the porous medium module is coupled. The computational capability of this model is verified first. Then, depending on the model, a series of cases are carried out to study the effects of different porous medium breakwaters on the propagation of the solitary wave. The results show that when the porosity is 0.8, the force on the submerged breakwaters is the smallest, and the water level and the velocity decrease seriously. With the increase in the diameter of the submerged breakwater, the wave profile gradually becomes flat. The higher the wave height, the more serious the wave deformation after passing through the submerged breakwater.

Development of Online-learning based Adaptive Anomaly Detection Algorithm for Monitoring Data Analysis on Caisson Type Breakwater

Most port structures are massive and data measured on them sensitively changes to the surrounding environment including sea waves, tides, wind, and other operational conditions so it might be difficult to extract and long-term monitor their own features such as natural frequencies and mode shapes. To solve this problem, an anomaly detection algorithm with online learning was developed for the analysis of monitoring data on the port structures. For this, data were first measured on a 1/50 scaled model of caisson type breakwater through hydraulic model experiments, and the characteristics of data were investigated. Then an unsupervised algorithm was developed to online detect abnormal conditions caused by the drift, which can track the reconstruction error from the principal component analysis and the Euclidean distance between original and reconstructed signals. The experimental results showed that the proposed algorithm could be successfully applied to time-dependent dataset shifts with high accuracy and automatically calculate the threshold based on the adaptive model.

A Study Coastal Protection Using Stones Crushed and Tetrapod (Case study at Ujong Blang Beach)

Ujong Blang Beach and Jagu Beach are in Lhokseumawe City. The purpose of this study was to plan a breakwater along the coast of Ujong Blang as an alternative for coastal protection. This includes specifying the details of the breakwater layers and calculating the dimensions of the breakwater. Applying the Hudson method to obtain the diameter and weight of stones grains. The protective layer material uses crushed stones and tetrapods. The results of the analysis obtained breakwater dimensions obtained based on a slope of 1: 2. The results of the analysis that have been obtained are made in the drawing 2D as a result of designing rock mounds with a slope of 1: 2. Breakwaters are planned in a position to protect the coast from waves. The planned breakwater height is 6.32 meters so it has the same elevation and crest dimensions, but the material volume will change less due to the lower contour differences in the sea.This type of breakwater is suitable for Ujong Blang beach, because it will have a good effect on the tourism business. The number of protected layer grains on a slope of 1:2 has a material use of 0.23 tons of tetrapods and a peak width of 3.5 meters.

Bragg Resonance of Water Waves by Multiple Permeable Thin Barriers over Periodic Breakwaters

In this study, the Bragg resonance of water waves scattered by multiple permeable thin barriers over a series of periodic breakwaters was solved by employing the eigenfunction matching method (EMM). The geometrical configuration was divided into multiple shelves separated by steps, on which thin permeable barriers were implemented. The solution was approximated using eigenfunctions with unknown coefficients that were considered as the amplitudes of the water waves for each shelf. The conservations of mass and momentum were then applied to form a system of linear equations, which was sequentially solved by a sparse-matrix solver. The proposed method degenerates to traditional EMM formulations if thin barriers, the permeability of the barrier, or bottom undulations are not considered. The validity of the suggested method was examined based on the results in the literature. Bragg resonances by bottom-standing, surface-piecing, and fully submerged permeable barriers over a series of periodic trapezoidal or half-cosine breakwaters were studied. In addition, the breakwater amplitudes, permeable parameters of the barriers, and incident angles of water wave scattering by different types of periodic breakwaters were discussed.

Recent Investigations on Wave Dissipation of New Type Breakwaters

The performances of wave dissipation, wave force and motion responses for new type breakwater are investigated in the study. Compare with the traditional breakwater, the wave dissipation effect for different new structure type are discussed, including the open plate breakwater, cylinder breakwater, pile breakwater, caisson breakwater, floating breakwater and flexible breakwater. It is found that, the new type breakwaters have advantages on wave damping, lower construction cost, convenient construction and little environment influence. Moreover, the ocean energy such as wave and offshore wind can be captured by optimizing the structure of breakwater. Therefore, it can attain the double effect of wave damping and clean energy utilization.

Numerical simulation of long-wave wave dissipation in near-water flat-plate array breakwaters

A plate system, composed of flat array is proposed to be one type of breakwater. At present, little research has been done on the wave elimination of the plate under long-period waves. The Reynolds-averaged Navier-Stokes (RANS) equations are treated based on three-dimensional closed RNG k-ε turbulence model and the governing equations are solved by VOF method. A numerical model of the interaction between wave and flat array breakwater is established to study the wave elimination performance of different wave period ang steep. The flow and vortex fields are solved to research the wave dissipation mechanism of breakwaters. Results show the wave transmission coefficient tends to increase with the increase of wave period. Wave transmitted coefficient are all less than 0.4 in this test, indicating that the flat array plate breakwater maintains a certain wave dissipation capacity for long-period waves. At the same period, the wave steepness change mainly affects the amount of water passing through the upper part of the flat plate, which has some influence on the way the breakwater dissipates energy. The plate spacing is the main wave energy dissipation area, which provides space for water exchange and effectively eliminate waves while reducing the amount of board. The results preliminarily demonstrated the potential application of flat plate array as a wave energy breakwater, but the flat plate parameter design and the interaction of waves and flat plates needs further research.