Pile Breakwater Research Articles

The Effectiveness of Inclined Pile Breakwater on the Transmission Coefficient

The Effectiveness of Inclined Pile Breakwater on the Transmission Coefficient

Numerical simulation of the interaction between waves and pile breakwater with horizontal slotted plates

Pile breakwaters are a coastal structure designed to protect harbors and coastlines from wave attacks while allowing water circulation and fish passage. Conventional pile breakwaters reduce wave transmission by decreasing porosity, but this increases wave reflection and impact on the breakwater. This study proposes a novel structure called pile breakwaters with horizontal slotted plates (PHSP) to enhance wave dissipation by inducing turbulence and jet phenomena. A comprehensive analysis using a numerical wave tank based on OpenFOAM and OlaFlow is conducted to simulate the interaction between waves and PHSP under various wave conditions. The numerical results are validated using experimental data and theoretical formulas and are compared with conventional pile breakwaters. The study investigates the effects of different parameters on wave transmission, reflection, and energy dissipation. The findings demonstrate that PHSP can effectively double wave energy dissipation, considerably reduce wave transmission, and adapt to diverse wave environments through parameter adjustments.

Investigation on innovative pile head breakwater for coastal protection

Coastal erosion is a global concern that has been augmenting due to the natural evolution of beaches, human activities and sea-level rise. One of the eco-friendly shore protection methods is to dissipate the wave energy by constructing offshore breakwaters. Conical pile head breakwater (CPHB) is one of the eco-friendly innovative offshore structures consisting of closely spaced piles with an enlarged cross-sectional area (conical pile head) in the vicinity of the free surface. In the present study, perforations are incorporated over the conical pile head to achieve higher efficiency by promoting energy dissipation. The influence of the perforations on the performance characteristics, namely wave transmission (Kt), wave reflection (Kr) and energy dissipation (Kd) of the perforated CPHB is comprehensively investigated through physical model studies. The effect of perforations and their distribution around the pile head (Pa), percentage of perforation (P) and size of perforations (S/D) on the wave attenuation characteristics are evaluated to arrive at an optimum configuration. The study is carried out under monochromatic waves of varying wave height (0.06–0.16 m) and wave period (1.4–2 s) at different depths of water (0.35, 0.40 and 0.45 m). A minimum Kt of 0.58 associated with Kr of 0.26 and Kd of 0.78 is obtained with an optimum configuration of Pa = 50%, P = 19.2% and S/D = 0.25. The Kt of the proposed CPHB is about 19 to 35% lesser than that of the perforated hollow pile breakwater under matching test conditions. Overall, providing the perforations is found to be effective in enhancing the wave attenuation capability by up to 12.4%. Further, empirical equations are formulated and validated with the experimental data. The empirical equations estimate the Kt and Kr values accurately with a high coefficient of determination ( R2 ≥ 0.90).

A laboratory study of wave-induced local scour at an emergent pile breakwater

A pile breakwater is a row of closely-spaced piles, placed in a side-by-side arrangement, to dissipate wave energy and prevent coastal erosion. It is important to understand the local scour at a pile breakwater for its foundation design. This paper reports a set of wave-flume tests on the local scour around the piles in regular waves. A laser scanner was used to measure the change in the three-dimensional bed elevation. Five values of Keulegan–Carpenter number were examined in this study. Scour holes near the pile breakwater were developed due to the oscillatory jet flow through the gaps between adjacent piles, and sand ripples were observed on both sides of the structure. The migration of the sand ripples was either onshore or offshore, depending on the wave conditions. The maximum scour-hole depth had an exponential growth with the duration of wave attack, and the equilibrium depth was found to be deeper than that for a standalone pile. Both the scour-hole depth and length were found to be scaled by the pile diameter. The ripple length and steepness were in general agreement with recent empirical formulas in the literature in spite of the presence of a pile breakwater.

Prediction of the Wave Run-Up on Pile Breakwaters

Prediction of the Wave Run-Up on Pile Breakwaters

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 Modelling of an Innovative Conical Pile Head Breakwater

When moderate wave activity at the shoreline is acceptable, pile breakwaters can serve as an alternative to conventional breakwaters. Increasing the size of the pile breakwater in the vicinity of the free surface increases the hydraulic efficiency, as most of the wave energy is concentrated around the free surface. Therefore, a conical pile head breakwater (CPHB) is proposed in the present study by gradually widening the diameter of the piles towards the free surface. Using the open-source computational fluid dynamics (CFD) model REEF3D, the transmission, reflection, and dissipation characteristics of the CPHB with monochromatic and irregular waves are examined. The investigation is carried out for both perforated and non-perforated CPHBs using monochromatic waves, and the numerical results are validated using experimental data. Further, optimally configured non-perforated and perforated CPHBs are investigated numerically by subjecting them to irregular waves using the Scott–Wiegel spectrum. The wave attenuation characteristics of the CPHBs are found to be better with irregular waves compared to monochromatic waves. With irregular waves, the minimum transmission coefficients for non-perforated and perforated CPHBs are 0.36 and 0.34, respectively. Overall, the CPHB appears to be a potential solution for coastal protection.

Hydroelastic Investigation on A Pile Breakwater Integrated with A Flexible Tail for Long-Wave Attenuation

A novel concept of wave attenuator is proposed for the defense of long waves, through integrating a flexible tail to the lee-side surface of a pile breakwater. The flexible tail works as a floating blanket made up of hinged blocks, whose scale and stiffness can be easily adjusted. A two-phase-flow numerical model is established based on the open-source computational fluid dynamics (CFD) code OpenFOAM to investigate its wave attenuation performance. Incompressible Navier—Stokes equations are solved in the fluid domain, where an additional computational solid mechanics (CSM) solver is embedded to describe the elastic deformation of the floating tail. The coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming body. The accuracy of the numerical model is validated through comparison with experimental data. Effects of the flexible tail on performance of the pile breakwater are investigated systematically. Dynamic behaviours of the tail are examined, and characteristics of its natural frequency are identified. For safety reasons, the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially examined. It is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater. A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile breakwater. The maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail.

Numerical Modelling of Wave Attenuation in Pile Breakwater

Pile breakwater is an artificial coastal structure consisting of closely spaced piles. Its benefits are similar to other coastal structures by attenuating the energy of the incoming wave. In this paper, the wave attenuation caused by the pile structure is investigated using a numerical model, namely the SWASH model. The model allows for simulating non-hydrostatic phenomena in coastal waters as driven by waves. The model setup is conducted in a rectangular wave flume with paddles to produce monochromatic waves on the left and the wave absorber on the other side. Several scenarios were carried out to determine the effect of variations in wave parameters. To deal with the efficiency of numerically modelled pile breakwater, we also investigate the transmission coefficient. We compare the result of the numerical model with experimental data, which took place in a wave flume at Balai Penelitian dan Pengembangan Pantai, Buleleng, Bali, Indonesia. The validation results demonstrate the capability of the SWASH Model to approximate the incident and transmitted wave height with good accuracy compared to experimental data.

An Experimental Study of Characteristics of Solitary-Wave-Induced Scour Around a Pile Breakwater with a Discussion on Effects of the Distance between Piles

Understanding tsunami-induced scour at a pile breakwater is important for the foundation safety of this type of coastal defense structures. A series of wave-flume tests were performed for [Formula: see text], with [Formula: see text] being the gap size and [Formula: see text] the pile diameter, to study the characteristics of the solitary-wave-induced local scour around a pile breakwater, including the scour-hole depth, scour-hole length, deposition sandbar height and the scoured volume. It was found that the jet flow through the gaps between piles caused the local scour around individual piles. A more or less two-dimensional deposition sandbar was found on the down-wave side of the pile breakwater in the later stage of the scour process. A new empirical equation was introduced to approximate the evolution of the depth of the scour hole induced by a series of solitary waves. The equation was verified by existing data reported in the literature for [Formula: see text] and the new data reported in this study. Effects of the distance between piles on the characteristics of the local scour were discussed by comparing the results for [Formula: see text] and 0.39. The comparison showed that the scour-hole depth and height of the sandbar for [Formula: see text] were all noticeably larger than the corresponding values for [Formula: see text].

ПОДХОД К СНИЖЕНИЮ БЕРЕГОВОЙ ЭРОЗИИ НА ОСНОВЕ ПРИМЕНЕНИЯ КОМПОЗИТНОГО СВАЙНОГО ВОЛНОЛОМА «ГРЕБЕНКА»

The article stresses actual importance of protection against coastal erosion almost all over the world, gives short overview of hydraulic structures traditionally used to combat erosion. The problems arising during the operation of such hydraulic structures, the restrictions imposed on them in various countries, are noted, which raises the question of the need to search for new solutions based on modern materials that surpass traditional analogues in strength and durability and create opportunities for new design solutions. One of such solutions is the modular pile breakwater “Comb” in the cover of composite materials, which protects the concrete body of the breakwater from the aggressive marine environment and destructive wave impact. “Comb” provides fast and convenient installation technology, which is several times faster than the speed of construction of traditional breakwaters and allows creating from modules any configuration that is optimal for solving problems of counteracting coastal erosion in a particular area. The design was investigated during several cycles of flume tests in one of the leading Russian specialized laboratories; results were obtained confirming the high efficiency of the Comb structure. This allowed the transition to full-scale field tests of the breakwater

Hydraulic performance of perforated enlarged pile head breakwaters through laboratory investigation

An economical, ecofriendly and efficient breakwater system is vital for coastal protection and harbour tranquility. In this regard, various researchers are working to develop the appropriate solutions to encounter site-specific challenges. With this viewpoint, concept of enlarged pile head breakwater is developed. The study focuses on improving the hydraulic efficiency of pile breakwater by enlarging the structure near the free surface and providing it with perforations. Effect of percentage distribution of perforations, size of perforations and percentage of perforations on wave transmission, reflection and dissipation characteristics of the structure is investigated. The physical experiments are conducted in a two-dimensional wave flume under varying monochromatic wave climates. Results indicate that the pore size highly dominants the wave attenuation than considering the increasing percentage of perforations with the small size of the pore. Perforations effectively reduce the Kt of about 10%–18% to that of non-perforated pile head breakwater. Hydraulic efficiency of enlarged pile head breakwater is optimum when D/Hmax = 0.6, Y/Hmax = 1.0, b/D = 0.2, S = 0.25D, pa = 75% and P = 22.5 at 0.3 m water depth. A hybrid theoretical solution is developed based on the current set of experimental data for the quick estimate of hydraulic coefficients. The proposed hybrid equation for the perforated pile breakwater predicts more desirable values of Kt, Kr and Kd. The proposed concept of breakwater gives a reasonably enhanced hydraulic efficiency than the compared type of breakwaters.

Performance characteristics of a conical pile head breakwater: An experimental study

Breakwaters are constructed for dissipating the wave energy and safeguarding the coastline from destructive wave forces. Conventional pile breakwater built using prismatic circular piles has been proven to provide partial protection efficiently. In the present study, the conventional pile breakwater is modified by widening the pile's cross-sectional area at the surface level in a conical shape. The concept of introducing the conical shape is to attenuate the concentrated wave energy, mainly focusing at the surface. The influence of the structural parameters such as diameter, height and clear spacing of the conical pile head is investigated experimentally for various monochromatic wave climatic conditions. The investigation is also focused on determining the influence of the second row on performance characteristics. The analysis shows that the least transmission coefficient (Kt) of 0.662 for the configuration of D/Hmax = 0.4, Y/Hmax = 1.5 and b/D = 0.1 for a single row of piles. Further, the second row of piles' inclusion resulted in improved attenuation characteristics of conical pile head breakwater (CPHB) with the least Kt of 0.582 at an optimal B/D of 0.4. The performance of the CPHB is compared with the theoretical solutions of conventional pile breakwater. The results indicate that the introduction of pile head on conventional pile breakwater is beneficial in improving wave attenuation. A set of empirical equations is developed based on the experimental values for quick prediction of Kt and Kr. The estimated values of Kt and Kr are in line with the experimental data with a coefficient of determination (R2) of 0.91 and 0.90, respectively. The overall performance of the CPHB is found to be promising as a potential coastal protection structure.

Flow pattern and hydrodynamic parameters of pile breakwater under solitary wave using OpenFOAM

Pile breakwaters are widely used for coastal protection. To ensure the safety and hence serviceability of pile breakwaters under disastrous waves like tsunamis, an accurate estimation of wave actions exerted on them is necessary. This work investigates the hydrodynamic properties of solitary waves (resemble tsunami waves) interacting with a single-row pile breakwater using OpenFOAM. Large eddy simulation (LES) is utilized to deal with the turbulent flow, and the free-surface is reproduced by a scheme named THINC/QQ (tangent of hyperbola for interface capturing with quadratic surface representation and Gaussian quadrature). This numerical model is validated against published experimental data. Using the verified model, flow patterns near the piles are interpreted. A parametric study is then conducted on the influences of incident wave height, blockage ratio and pile diameter to the hydrodynamic parameters of pile breakwater, which include wave run-up, wave force and jet velocity. Finally, semi-empirical formulas are established for quick and reliable evaluation of these parameters. The research work can provide guideline for practical design of pile breakwater.

Hydrodynamic performance characteristics of an oscillating water column device integrated with a pile breakwater

Hydrodynamic performance characteristics of an oscillating water column device integrated with a pile breakwater

ANALISIS REFLEKSI DAN TRANSMISI GELOMBANG PADA PEMECAH GELOMBANG TIANG PANCANG

Pantai berlumpur rentan terhadap kerusakan akibat gelombang, sehingga diperlukan perlindungan pantai yang salah satunya menggunakan pemecah gelombang tipe permeable. Tipe permeable yang dikembangkan ini disebut sebagai Pemecah Gelombang Tiang Pancang. Bahan yang digunakan untuk memodelkan struktur tersebut (prototipe) di laboratorium adalah bambu bulat bersekat yaitu bambu bulat dari taman Pringgodani dengan diameter 1 cm, tinggi 20 cm dengan sekat kayu multiblok setebal 2 cm. Analisis refleksi dan transmisi terhadap hasil pengujian model fisik 2D terhadap pemecah gelombang diperlukan untuk mencapai optimasi dalam penggunaannya. Hasil pengujian laboratorium membuktikan bahwa Pemecah Gelombang ini cukup efektif pada skenario yang memiliki nilai Kt yang lebih kecil dan nilai Kr yang lebih besar. Pada percobaan ini pengujian dilakukan dengan skenario tinggi muka air pada Mean Sea Level (MSL) (44 cm) dan High Water Level (HWL) (50 cm) dengan 2 skenario spasi antar tiang yaitu 1 cm dan 2 cm pada masing-masing tinggi muka air. Kemudian hasil perhitungan Kt dan Kr dibandingkan dengan variabel non-dimensional kecuraman gelombang (Hi/gT2) dan kemiringan gelombang (Hi/L) . Hasil percobaan laboratorium menunjukkan bahwa nilai Kt lebih rendah pada saat kondisi MSL, dan nilai Kr lebih tinggi pada saat kondisi MSL hal ini menunjukkan bahwa Pemecah Gelombang Bambu Bulat Bersekat ini lebih efektif pada muka air rendah dari pada muka air tinggi.

Efficiency of Double Rows of Piles Used As A Breakwater (Dept.C)

The wave transmission, reflection, and energy loss due to closely spaced pile breakwaters consisted of two rows of vertical piles were investigated experimentally. Different parameters were tested such as, the gap-diameter or width ratio, the relative distance between the rows of piles, the wave length, the shape of the piles (square or circular), and the arrangement of the piles (straight or staggered). The square pile breakwater was found to be more efficient than the circular piles in decreasing the transmitted waves. Also, it was concluded that the efficiency of the breakwater was increased as the gap-diameter or width ratio decreased and as the relative span between pile rows increased. Finally, it was noticed that the effect of the pile arrangement (straight or staggered) was slightly affected the breakwater efficiency.

Theoretical Study for One Row of Piles Used As A Breakwater(Dept.C)

The performance of the pile breakwater consisted of one row of vertical circular or square piles was investigated theoretically using the Eigenfunction expansion method. The transmission and the reflection coefficients were calculated for different wave and structure parameters. The validity of the theoretical model was examined by comparing the results with the theoretical and the experimental results from different studies. It was concluded that; the proposed theoretical model could be used efficiently to predict the performance of the pile breakwaters consisting of one row.

Laboratory investigation on hydraulic performance of enlarged pile head breakwater

Coastal erosion of beaches has been a common problem around the world. One of the eco-friendly control measures for coastal erosion is to dissipate the energy of waves impinging on the shores by constructing offshore breakwater. Pile breakwater is one such type of offshore breakwater that consists of a number of closely spaced piles. Construction of piles at closer spacing is highly challenging and expensive. This problem can be addressed by reducing the number of piles and modifying the pile with an enlarged head in the vicinity of the water surface, where wave energy is concentrated. In the present study, an experimental investigation on the hydraulic performance of enlarged pile head breakwater is conducted in a wave flume. The concept breakwater is subjected to monochromatic waves of varying wave heights, wave periods and water depth. The experimental results show that the least value of transmission coefficient is 0.62 and reflection coefficient is 0.123 with the highest value of dissipation coefficient of 0.77 for the structural configuration of b/D ratio of 0.2, D/Hmax of 0.6 and Y/Hmax of 1.0 at a water depth of 0.3 m. Observed results are encouraging and are in line with the similar type of pile breakwaters in a single row. The present experimental data is also validated with the available theoretical solutions. Since the results from the compared theoretical solution are not in good agreement, a hybrid theoretical model is reconstructed based on experimental results of pile head breakwater. The proposed modified version of the hybrid equation predicts encouragingly better transmission, reflection and dissipation coefficient than the existing solutions. Moreover, the results predicted by the proposed hybrid equation are in good agreement with that of other similar pile breakwater models.

Investigation on hydrodynamic performance of an environmentally friendly pile breakwater

In this paper, a type of pile breakwater is studied in a configuration that can provide an effective shore protection structure. While, the rubble mound breakwaters are the most common type, but they suffer from a number of shortcomings including the interruption of water that may lead to deterioration of water quality and corresponding environmental problems. The breakwater of this study with rows of piles can be used against sea waves, as an alternative. Its hydraulic performance, including wave reflection and transmission, shear stresses, pressure measurements, drag and inertia coefficients are investigated. In the first step, the hydrodynamics around the mono-piles with square cross-sections are inspected. The parametric equations are developed to measure the optimal orientation of the piles. As evidenced in the literature, relatively limited works have been carried out on this kind of piles. Also, the performance of the considered pile breakwaters are evaluated. To do this, the numerical results are calibrated and validated by experimentation. It is observed that the group piles with the square cross-section in optimum conditions, could have a higher value of reflection almost between 7 even to almost 30 percent, than other considered conditions with mild and short waves. It can be related to the effect of the square piles edges on the separation process of the flow.