Characteristics Of Wave Forces Research Articles

Numerical study of waves breaking on a vertical pile with different cross-sections

A three-dimensional numerical model is established to simulate the interaction between breaking waves and a vertical pile. The primary aim of this study is to explore the influence of pile cross-section shape on inline wave forces under different wave breaking stages. Besides the common circular, squircle, and square cross-sections, a novel pile proposed by Yang et al. (2020), consisting of a front diamond surface and a circular back, is also considered. A comparison of breaking wave force characteristics is performed for these four piles in various wave steepnesses. The results indicate that changes in the cross-section shape result in alterations to the inline force magnitude, whereas the transitions of the wave breaking stage not only quantitatively modify the inline force magnitude but also qualitatively alter the force curve shape. Special attention is then paid to a detailed analysis of the flow evolution and force distribution to gain insights into the generation of the peak force and the secondary load cycle (SLC). Furthermore, the numerical results are analyzed in the frequency domain, revealing that higher harmonics beyond the eighth order are not associated with the SLC, but are intimately related to the peak breaking wave force.

Time Response Analysis of Caissons by Installing New Caisson on Existing Caisson Breakwater in Irregular Wave Condition

The design and the construction were carried out by installing new caissons on the back or the front of existing caissons to increase the structural stability of caisson breakwaters. In this study, we used the ANSYS AQWA program to analyze the wave forces acting on individual caissons according to the effects of wave-structure interaction when new caissons were additionally installed on existing caisson breakwaters. The wave force characteristics acting on the individual caisson were analyzed according to the distance among caissons in frequency domain analysis. In addition, the dynamic wave force characteristics were closely examined on the basis of the frequency at which the unusual distribution of wave forces occurs in irregular wave conditions using time domain analysis.

Interaction Analysis between Waves and Caissons by Damping Zone Effect for Installing New Caisson on Old Caisson Breakwater

The design and construction are carried out to improve the structural stability of caisson breakwaters by installing new caissons on the front or rear of old caissons. The wave forces acting on caisson are excessively calculated by the resonance of fluid existing between the old caisson and the new caisson in the numerical analysis using potential flow. In this study, we used the damping zone option in ANSYS AQWA program to analyze the wave forces acting on individual caissons according to the interaction effects between the incident wave and the caisson. By applying the damping zone option to the fluid in which resonance occurs, the wave forces acting on individual caissons were calculated by the change of damping factor. In addition, the wave force characteristics acting on individual caissons were analyzed for the different distances between caissons in the frequency domain analysis.

Interaction Effect between Caissons by Installation of New Caisson on Existing Caisson Breakwater in Second Order Stokes Wave Condition

In order to increase the structural stability of existing caisson breakwater, the design and the construction is carried out by installation of new caissons on the back or the front of old caissons. In this study, we use the ANSYS AQWA program to analyze the wave forces acting on individual caisson according to effects of wave structure interaction when new caissons are additionally installed on existing caisson breakwater. Firstly, the wave force characteristics acting on the individual caisson were analyzed for each period (frequency) in the frequency domain. In time domain analysis, the dynamic wave force characteristics were strongly influenced by the distance between caissons on the frequency at which the unusual distribution of wave forces occurs.

Numerical investigation on the wave force characteristics of multi-cylinder with equilateral-triangular arrangement

Based on the open source program DualSPHysics, a numerical investigation is carried out on the hydrodynamic characteristics of multi-cylinder with equilateral-triangular arrangement and the wave field distribution characteristics under the action of regular waves. With the SPH method, the hydrodynamic response characteristics of multi-cylinder with equilateral-triangular arrangement are analyzed under different wave directions. The phase difference distribution characteristics of the wave force on multi-cylinder with equilateral-triangular arrangement are analyzed, as well as the wave field distribution characteristics under different wave angles. In addition, the wave force distribution characteristics and the phase difference distribution characteristics of multi-cylinder with equilateral-triangular arrangement are explored under different wave parameters (wave period and wave height). Through the observations of the hydrodynamic forces induced by the wave, the phase difference of these forces on upstream cylinder and downstream cylinder is the largest when the wave angle is 30°. The maximum wave force of the cylinder is roughly proportional to the distance between the center of the cylinder and the x-axis centerline of the wave field.

Characteristics of wave forces on pile group foundations for sea-crossing bridges

The pile group foundation of sea-crossing bridges has various structural forms, and its wave force characteristics are complex. In this study, the Morrison equation and the boundary element method were utilized to establish a calculation model for predicting the maximum wave forces on the pile group foundation with a square pile cap. Moreover, hydrodynamic models of pile group foundations were designed according to the gravity similarity criterion. On this basis, the model test and analytical calculation were carried out to investigate the effect of pile spacings, pile slopes, conical slopes (on the top of the pile cap), and wave parameters on wave forces of pile group foundations. In addition, impact characteristics of waves on the foundation were also analyzed. The results shown that larger pile spacings and pile slopes reduced the wave forces on the foundation, but this relationship weakened with the rise of the water level. The inclined pile could be regarded as a vertical pile for calculating wave forces at high water level. The conical slope increased the water-blocking area on the pile cap, which led to the increase of wave forces on the foundation. When the wave only acted on the pile group, the wave forces on the single pile firstly decreased then increased with the increase of frequencies, and lower wave frequencies (larger periods) induced stronger nonlinear factors of the waves. When the water level was near the bottom of the pile cap, larger wave periods increased the vertical wave forces on the pile cap. The wave impact mainly occurred in the time range from the pile cap first contacting with the wave to the wave crest reaching the middle of the pile group foundation.

Reliability-based retrofit assessment of coastal bridges subjected to wave forces using 3D CFD simulation and metamodeling

ABSTRACT This paper proposes a comprehensive analysis framework, combining three-dimensional (3D) numerical modelling and metamodeling, to investigate the probabilistic performance of retrofit actions on coastal bridges subjected to extreme wave forces. Specifically, a 3D Computational Fluid Dynamics (CFD) model is developed to calculate extreme wave load on the bridge superstructure. The established 3D model is validated by laboratory experiments. The characteristics of wave forces are parametrically investigated, and an Artificial Neural Network (ANN) metamodel is utilised to quantify the loading effects with multiple surge and wave parameters. Such a numerical-based ANN metamodel could predict wave forces under variable scenarios accurately, and significantly reduce the high computational cost of the 3D numerical model. Based on the numerical and metamodeling results, the bridge fragility curve is derived by considering uncertainties associated with structural demand, capacity, and hurricane hazard. Long-term failure risk is assessed under different climate change scenarios. Furthermore, different retrofit methods to improve structural performance and reduce failure risk are examined according to the proposed framework, including inserting air venting holes, enhancing connection strengths, and elevating bridge structures. The proposed framework could facilitate the optimal and robust design and maintenance of coastal infrastructures under hurricane effects in a long-term time interval.

The influence of regular wave and irregular wave on the mechanical characteristics of a triple-cylinder bundle structure

By using the open source DualSPHysics, the interaction between wave and a triple-cylinder bundle structure is numerically investigated. The wave is generated by applying the predefined function to the wave maker, and the free surface and the velocity of the regular wave and irregular wave are compared with the theoretical data at the measuring point. To verify the feasibility of the numerical method for simulating the fluid-structure interaction, the numerical results of smooth particle hydrodynamics (SPH) model are compared with the experimental and theoretical data, which shows a good agreement. Finally, 95 groups of cases of the interaction between wave and triple-cylinder bundles (TPB) are calculated, and the wave force acting on TPB is explored at different rotation angles. The effects of different wave parameters on the wave force characteristics are further analyzed. The results of a single vertical cylinder are introduced for making a comparison. For the regular wave case, the wave force acting on the structure is higher than that of the irregular wave case. When the rotation angle is 90°, the wave force on the TPB is the maximum; and it reaches the minimum at 180°.

Wave Force Characteristics and Stability of Detached Breakwaters Consisting of Open Cell Caissons Interlocked via Crushed Stones

The maximum external force acting on a long continuous harbor structure can be reduced by controlling the phase difference of forces acting longitudinally. This strategy can be used to increase the structural stability of breakwaters consisting of caissons. Breakwaters have been developed using interlocking caissons to effectively respond to the constant increase in wave height due to climate change. In this study, we investigated the wave force characteristics and stability of a detached breakwater consisting of open cell caissons interlocked via crushed stones. We performed wave basin experiments and compared the results with analytical solutions of linear diffraction waves. The results revealed that the maximum wave force acting on the front of the breakwater decreased as the incident angle increased, reducing by as much as 79% for an incident angle of 30°. Although the variability of the maximum wave force for each caisson is large owing to the influence of the diffracted waves, the maximum wave force acting on the entire detached breakwater was not significantly affected by this variability. The analytical solutions based on linear wave theory agreed with the experimental results, indicating that the findings can be applied to actual designs. The structural stability of the breakwater was enhanced, even for low incident wave angles, compared to that of a single integral structure, as the frictional resistance produced by the sliding structure increased due to the shear resistance between the filled crushed stones and the rubble mound.

Characteristics of Wave Forces by Installation of New Circular Caisson on the Back of Old Circular Caisson

Characteristics of Wave Forces by Installation of New Circular Caisson on the Back of Old Circular Caisson

Wave Force Characteristics of Large-Sized Offshore Wind Support Structures to Sea Levels and Wave Conditions

This paper presents the results of wave force tests conducted on three types of offshore support structures considering eight waves and three sea levels to investigate the corresponding wave forces. As a result of this study, it is found that the occurrence of shoaling in shallow water induces a significant increase of the wave force. Most of the test models at the shallow water undergo a nonlinear increase of the wave force with higher wave height increasing. In addition, the larger the diameter of the support structure within the range of this study, the larger the diffraction effect is, and the increase in wave force due to shoaling is suppressed. Under an irregular wave at the shallow water, the wave force to the long-period wave tends to be slightly higher than that of the short period wave since the higher wave height component included in the irregular wave has an influence on the shoaling. In addition, it is found that the influence of shoaling under irregular wave becomes more apparent in the long period.

Design and Experiment Analysis of a Direct-Drive Wave Energy Converter with a Linear Generator

Coastal waves are an abundant nonpolluting and renewable energy source. A wave energy converter (WEC) must be designed for efficient and steady operation in highly energetic ocean environments. A direct-drive wave energy conversion (D-DWEC) system with a tubular permanent magnet linear generator (TPMLG) on a wind and solar photovoltaic complementary energy generation platform is proposed to improve the conversion efficiency and reduce the complexity and device volume of WECs. The operating principle of D-DWECs is introduced, and detailed analyses of the proposed D-DWEC’s floater system, wave force characteristics, and conversion efficiency conducted using computational fluid dynamics are presented. A TPMLG with an asymmetric slot structure is designed to increase the output electric power, and detailed analyses of the magnetic field distribution, detent force characteristics, and no-load and load performances conducted using finite element analysis are discussed. The TPMLG with an asymmetric slot, which produces the same power as the TPMLG with a symmetric slot, has one fifth detent force of the latter. An experiment system with a prototype of the TPMLG with a symmetric slot is used to test the simulation results. The experiment and analysis results agree well. Therefore, the proposed D-DWEC fulfills the requirements of WEC systems.

Scale effect on wave force characteristics of the structures supporting offshore wind turbines

In order to meet the pressing requirements of large-capacity offshore wind turbines, the scale of foundation structures tends to be larger and larger. These large structures may be hydrodynamically neither small scale nor large scale. For this type of intermediate scale structures, it is significant for offshore wind turbine design to figure out the wave force composition and the calculation method. This paper establishes a numerical wave tank, and analyzes wave force on a vertical circular cylinder by numerical simulation. By solving the Navier-Stokes equations and the Euler equations respectively, the viscous force and inertia force are separated reasonably. Furthermore, the law of viscous force and inertia force varying with the scale of cylinder is discussed. Finally, the significant scale intervals of marine structures and their wave force calculation methods are given.

Breaking solitary waves and breaking wave forces on a vertically mounted slender cylinder over an impermeable sloping seabed

In the present study, breaking solitary waves over a sloping seabed and breaking wave forces on a vertically mounted cylinder are simulated with the three-dimensional CFD model REEF3D. The numerical model uses the Reynolds-Averaged Navier–Stokes (RANS) equations together with the level set method (LSM) for the free surface and the $$k-\omega $$ for the turbulence. The numerical model is validated for simulating breaking solitary waves and breaking wave forces against the experimentally measured free surface profiles and vertical and horizontal velocities by Mo et al. (Ocean Eng 74:48–60, 2013) and the experimentally measured free surface elevation and breaking wave force by Chakrabarti et al. (Appl Ocean Res 19:113–140, 1997). The main purpose of the paper is to examine the effects of the breaking characteristics, the geometric properties, the relative cylinder positions and the incident wave heights on the breaking wave force characteristics. A total of 21 simulations are performed to investigate the characteristics and the geometric properties of solitary waves breaking over a slope and the associated breaking wave forces on a cylinder. First, the characteristics and geometric properties of breaking solitary waves are investigated with two-dimensional simulations. Further, the study explores the effect of the relative distance between the breaking point and the cylinder on breaking wave forces. Finally, the study examines breaking solitary wave forces for different incident waves. This also includes the analysis of breaking wave force characteristics such as the impact duration and rise time, the peak force, the average slamming coefficient and the force impulse. The results of the numerical simulations show that the relative distance between the cylinder and the breaking point plays an important role in obtaining the maximum force. In addition, the numerical model is capable of representing the most important physical flow features related to the breaking solitary waves and the interaction with the vertical slender cylinder.

Dispersion Characteristics of Wave Forces on Interlocking Caisson Breakwaters by Cross Cables

Damage level of coastal structures has been scaled up according to increase of wave height and duration of the storm due to the abnormal global climate change. So, the design criteria for new breakwaters is being intensified and structural strengthening is also conducted for the existing breakwaters. Recently, interlocking concept has been much attention to enhance the structural stability of the conventional caisson structure designed individually to resist waves. The interlocking caisson breakwater may be survival even if unusual high wave occurs because the maximum wave force may be reduced by phase lags among the wave forces acting on each caisson. In this study, the dispersion characteristics of wave forces using interlocking system that connect the upper part of caisson with cable in the normal direction of breakwater was investigated. A simplified linear model was developed for computational efficiency, in which the foundation and connection cables were modelled as linear springs, and caisson structures were assumed to be rigid. From numerical experiments, it can be found that the higher wave forces are transmitted through the cable as the angle of incident wave is larger, and the larger the stiffness of the interlocking cable makes larger wave dispersion effect.

DISPERSION OF WAVE FORCES ON CAISSON BREAKWATERS USING INTERLOCKING SYSTEMS

Interlocking caisson-type breakwaters have recently gained attention for enhancing the stability of the conventional breakwaters. In this study, the dispersion characteristics of wave forces using interlocking systems connecting the upper part of caissons with cables in the normal direction of breakwaters were investigated. Based upon numerical experiments, the higher wave forces are transmitted through the cable as the angle of incident wave increases, while the maximum allowable wave force was capable of being increased by sharing the wave forces with the adjacent caissons. It was also found that the larger the stiffness of the interlocking cable, the larger the wave-dispersion effect.

Wave Forces on Biloxi Bay Bridge Decks with Inclinations under Solitary Waves

AbstractHurricane Katrina in 2005 displaced or washed away a number of coastal bridges, including the Biloxi Bay Bridge. Although some experimental and numerical studies have been conducted to reveal the failure mechanisms of bridges under extreme nature disasters, very few previous studies are focused on the bridge decks with inclinations. In the present study, the wave forces on the bridge decks with inclinations (−10°–10°) under solitary waves have been investigated using the Biloxi Bay Bridge as the prototype bridge. Seven different structure elevations are considered to represent different conditions in field. Wave forces under the prescribed conditions, including the horizontal forces, vertical forces, and moments are analyzed in detail. The results show that the characteristics of wave forces under solitary wave conditions vary with different deck inclinations and structure elevations.

氷板混合津波が橋桁に及ぼす波力特性に関する実験的研究

In the event of a winter tsunami, there is the concern that floating ice sheets originating from sea ice might impact structures if the ice is carried by tsunami run-up. Accordingly, we conducted hydraulic model tests that reproduced the vertical and longitudinal behaviors of floating ice sheets carried by tsunami run-up. We clarified the characteristics of wave force for tsunamis that contain sea ice sheets and the impact of such tsunamis against bridge girders. In this test we reproduced a flow that contained solid substances and liquid substances. We confirmed that the wave force of a tsunami whose ice cover rate is 80% is about 2.5 times the wave force of a tsunami that contains no ice. We succeeded in showing the wave force characteristics of tsunami waves containing water and ice running up rivers in winter for bridge girder structures.

セルラーブロックを用いた新たな防波堤整備工法の開発と現地への適用

Most breakwaters in Japan are caisson breakwaters. However, the lower is the number of caissons constructed in a year, the higher is the construction cost per caisson, because the cost of floating dock operation is fixed, irrespective of caisson number. Therefore, a construction method was developed in which breakwaters are constructed not of caissons but of connecting cellular blocks. This paper proposes a design method for connecting cellular blocks and examines wave force characteristics in the construction stage by using hydraulic model tests. It was found that the proposed construction method could cut the project cost by 15% and could cut the project duration by 3 years at the Port of Setana.

Influence of Long Period Waves on Seawall Wave Force with Large-scale Artificial Reef

This study aims to investigate the characteristics of wave force on the seawall with a large-scale artificial reef, in Shimane Nuclear Power Plant facing to the Sea of Japan. Field observations were carried out to measure the wave field and the wave pressure on the seawall. From the comparison between field observations and numerical analysis by CADMAS-SURF/3D which is a three-dimensional numerical wave tank model, we clarified that the nonlinearity of the primary waves, wave direction, and reflection by the seawall cause the increase of the amplitude of the long period waves. As a result we confirmed that the wave force on the seawall increases in proportion to the amplitude of the long period waves.