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Integrating wave energy devices with coastal structures is a promising solution to reduce the cost of wave energy development along with additional shared benefits. In this study, the performance of a heaving spherical point absorber wave energy converter model in irregular waves is analysed and compared experimentally and numerically. After the fundamental investigation of models in regular waves, it is important to advance the testing in more realistic conditions before the sea trial phase. The investigations are conducted in irregular waves on a 1:30 scale model under two scenarios, (1) model heaving alone and (2) model heaving in a chambered breakwater. Irregular waves are generated based on the JONSWAP spectrum with modified parameters to suit the Indian coastal conditions. Results indicate that the wave energy converter model in the chambered breakwater produces 40.25 % higher power than the model heaving alone in irregular sea conditions. The performance of the model is found to be less compared to that in regular waves. [ABSTRACT FROM AUTHOR]

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Offshore triceratops is one of the successful manifestations of the form-dominant design approaches deployable in ultra-deepwater oil and gas exploration. The deck's geometric shape and partial isolation from the legs counteract lateral loads. Legs are position-restrained to the sea bed by taut-moored tendons, while ball joints partially isolate the deck from the buoyant legs. However, compliance in the horizontal plane imposes large displacements, intuiting the necessity to examine tendon failure. Numerical analysis of triceratops under wave and wind combined action is carried out under the postulated conditions of a tendon failure. 10-yr, 100-yr, and 1 000-yr post-Katrina hurricane conditions are assumed as loading to the platform. Results confirm a marginal increase in the natural periods of stiff degrees of freedom even under postulated failure conditions, ensuring good adaptability to ultra-deep water. Under postulated failure, the tension of adjacent tendons varies significantly, causing a shift to the mean position of the platform. Fatigue life is significantly reduced under the postulated failure of tendons, making the platform free-floating without affecting its stability. Results also show that the pitch response of the deck is a clear manifestation of the postulated failure, which is otherwise absent due to the presence of ball joints. The attempted study deliberates on the fatigue life of tendons, assessing the platform's suitability to ultra-deep waters and identifying the vulnerable legs for the chosen load combinations. [ABSTRACT FROM AUTHOR]

The propagation of shallow-water waves may cause liquefaction of the seabed, thereby reducing its support capacity for pipelines and potentially leading to pipeline settlement or deformation. To ensure the stability of buried pipelines, it is crucial to consider the excess pore pressure induced by irregular waves thoroughly. This paper presents the findings of an experimental study on excess pore pressure caused by irregular waves on a sandy seabed. A series of two-dimensional wave flume experiments investigated the excess pore pressure generated by irregular waves. Based on the experimental results, this study examined the influences of irregular wave characteristics and pipeline proximity on excess pore pressure. Using test data, the signal analysis method was employed to categorize different modes of excess pore-water pressure growth into two types and explore the mechanism underlying pore pressure development under the influence of irregular waves. [ABSTRACT FROM AUTHOR]

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves. [ABSTRACT FROM AUTHOR]

In this work, we conducted a numerical analysis of an oscillating water column (OWC) wave energy converter (WEC) device. The main objective of this research was to conduct a geometric evaluation of the device by defining an optimal configuration that maximized its available hydrodynamic power while employing realistic sea data. To achieve this objective, the WaveMIMO methodology was used. This is characterized by the conversion of realistic sea data into time series of the free surface elevation. These time series were processed and transformed into water velocity components, enabling transient velocity data to be used as boundary conditions for the generation of numerical irregular waves in the Fluent 2019 R2 software. Regular waves representative of the sea data were also generated in order to evaluate the hydrodynamic performance of the device in comparison to the realistic irregular waves. For the geometric analysis, the constructal design method was utilized. The hydropneumatic chamber volume and the total volume of the device were adopted as geometric constraints and remained constant. Three degrees of freedom (DOF) were used for this study: H 1 / L is the ratio between the height and length of the hydropneumatic chamber, whose values were varied, and H 2 / l (ratio between height and length of the turbine duct) and H 3 (submergence depth of hydropneumatic chamber) were kept constant. The best performance was observed for the device geometry with H 1 / L = 0.1985, which presented an available hydropneumatic power P h y d of 29.63 W. This value was 4.34 times higher than the power generated by the worst geometry performance, which was 6.83 W, obtained with an H 1 / L value of 2.2789, and 2.49 times higher than the power obtained by the device with the same dimensions as those from the one on Pico island, which was 11.89 W. When the optimal geometry was subjected to regular waves, a P h y d of 30.50 W was encountered. [ABSTRACT FROM AUTHOR]

The presence of twin hulls of a catamaran has a strong impact on wave pattern in the whole inner region due to interference between waves generated by each demi-hull. Consequently, wave profiles as well as wave height become complicated and unpredictable in the inner region not only in still water, but also in the presence of waves. Determining wave characteristics between demi-hulls of the catamaran is essential for predicting the operation of an autonomous underwater vehicle (AUV) throughout the launch and recovery (LAR) process. This study performed an experiment to investigate wave characteristics between demi-hulls of the catamaran under regular and irregular waves at various wave directions and speeds. The experiment was designed to measure wave elevation in the inner region between demi-hulls in waves using ultrasonic sensors and capacitance wave probes. The experimental method and setting were verified exacting by comparing the motion response of the catamaran measured by the Qualisys system with numerical simulation using the 3D panel method. Then, wave elevation in the inner region was measured and analyzed to wave height which is a representative parameter of regular waves and to wave spectral density and significant wave height which are representative parameters for irregular waves. These parameters were compared to those of the ocean waves to understand influences of wavelengths, sea states, wave directions, and speeds on wave characteristics between demi-hulls of the catamaran. Plotting of difference from ocean waves indicated the discrepancy in wave characteristics among positions in the inner region, wavelengths, wave directions, sea states, and speeds compared to ocean waves. Results of wave characteristics in the inner region are valuable to analyze motion response and behavior of AUV during LAR process of unmanned surface vehicle (USV).

A multi-body wave energy converter, consisting of three floats and modeled as a two body problem, is optimised to enhance its mean absorbed power using the Response Surface Optimisation Method. The optimisation focuses on two input parameters namely; the floats' diameters and the spacing, in various sea states and at different PTO dampings. A frequency domain analysis is performed for the WEC model scaled at 1:50 in regular and irregular waves. Obtained results are validated against numerical and experimental data available in the literature. Validations show good agreement against the unmoored model's added mass, radiation damping, response amplitude operator, mean absorbed power and, capture width ratio. The sea states selected for optimisation are represented by a JONSWAP wave spectrum with, a range of significant wave heights (0.04 to 0.06 m) and a range of peak periods (0.8 to 1.3 s). This corresponds to (2 to 3 m) significant wave heights and (5.6 to 9.2 s) peak periods in full scale. Results show that the optimised WEC model demonstrates good and consistent enhancement of its mean absorbed power and capture width ratio. [ABSTRACT FROM AUTHOR]

Given the increasing global energy demand, the present study aimed to analyze the influence of bathymetry on the generation and propagation of realistic irregular waves and to geometrically optimize a wave energy converter (WEC) device of the oscillating water column (OWC) type. In essence, the OWC WEC can be defined as a partially submerged structure that is open to the sea below the free water surface (hydropneumatic chamber) and connected to a duct that is open to the atmosphere (in which the turbine is installed); its operational principle is based on the compression and decompression of air inside the hydropneumatic chamber due to incident waves, which causes an alternating air flow that drives the turbine and enables electricity generation. The computational fluid dynamics software package Fluent was used to numerically reproduce the OWC WEC according to its operational principles, with a simplification that allowed its available power to be determined, i.e., without considering the turbine. The volume of fluid (VOF) multiphase model was employed to treat the interface between the phases. The WaveMIMO methodology was used to generate realistic irregular waves mimicking those that occur on the coast of Tramandaí, Rio Grande do Sul, Brazil. The constructal design method, along with an exhaustive search technique, was employed. The degree of freedom H1/L (the ratio between the height and length of the hydropneumatic chamber of the OWC) was varied to maximize the available power in the device. The results showed that realistic irregular waves were adequately generated within both wave channels, with and without bathymetry, and that wave propagation in both computational domains was not significantly influenced by the wave channel bathymetry. Regarding the geometric evaluation, the optimal geometry found, (H1 / L)0 = 0.1985, which maximized the available hydropneumatic power, i.e., the one that yielded a power of 25.44 W, was 2.28 times more efficient than the worst case found, which had H1/L = 2.2789. [ABSTRACT FROM AUTHOR]

This study presents novel analytical solutions for analyzing wave dissipation effect and bottom flow field characteristics of permeable submerged horizontal plates through physical model trials. The experimental results show that a solid submerged horizontal plate effectively attenuates wave cycles, with a greater periodic attenuation effect at smaller submerged depths. However, this attenuation effect becomes reduced or less pronounced after a certain threshold. Selecting an optimal opening ratio becomes key to achieving the desired cycle attenuation. When the inundation depth of the horizontal plate is large, the wave dissipation effect is weak. Reducing the opening rate can improve the wave dissipation effect, but only to a certain extent. Under irregular wave actions, the velocity field of the submerged horizontal plate is uniformly distributed. The relative submerged depth has minimal effect on the maximum flow velocity and root mean square flow velocity. Increasing the wave height and increasing the open holes on a plate can improve the flow velocity at the bottom of the plate. However, increasing the opening ratio also leads to insignificant changes in flow velocity. A correlation between the transmission coefficient of the open plate and the maximum flow velocity has also been determined. The findings of this paper serve as a research foundation for the implementation of submerged horizontal plate wave dissipation structures in engineering. [ABSTRACT FROM AUTHOR]

A variety of floating structures at sea play a vital role in the exploitation and utilization of marine resources. The study about interactions between waves and structures is necessary for the impact of the harsh marine environment on the motion and service life of structures. Currently, most studies about the seakeeping of structures are based on simplified regular waves. Because the regular waves do not truly restore the actual wave conditions at sea, the simulation of irregular waves has great practical importance to the study of interactions between waves and structures. Based on the potential flow theory and high-order boundary element method (HOBEM), a Fortran code is developed in this paper and named as SWBI (Solver for Wave–Body Interactions). This program consists of the following two parts: a time–domain numerical model about interactions between waves and 3D structures is based on weakly nonlinear method, and a numerical model about simulation of the nonlinear regular waves, the long-crested irregular waves, and the short-crested irregular waves. This Fortran code is used to simulate the motion of Floating Production Storage and Offloading (FPSO) under three different ocean wave spectra (including ITTC two-parameters spectrum, JONSWAP spectrum and the most likely spectral form of Ochi-Hubble) and found that: To a certain extent, the difference in the motion of FPSO under different wave spectra have a connection with different type of wave, sea conditions and incident angle. The difference in roll of FPSO is quite significant in short-crested irregular waves. The range of FPOS's roll under the JONSWAP spectrum is the largest when the incident angle is 30°, and range of FPOS's roll under the most likely spectral form of Ochi-Hubble is the largest when the incident angle is 90°. [ABSTRACT FROM AUTHOR]

Studying the dynamic characteristics of the platform under unsteady loads is of great significance to the development of floating offshore wind turbines (FOWTs). In this work, a 15 MW semi-submersible FOWT is extensively simulated using OPENFAST software, and the influence of turbulent wind and irregular waves on the platform's motion is analyzed in detail. Results show that the surge motion of the platform of a complete FOWT system is mainly affected by wind speed, and the influence of turbulence intensity (TI) is slightly greater than the wave height. The heave motion is most significantly affected by the wave height. When the wave height is large, the influence of wind speed on the platform gradually decreases, and the effect of TI becomes more evident. The pitch and yaw motions are greatly affected by the wind speed and TI. The research results can serve as a reference for the platform design of large FOWTs in the future. [ABSTRACT FROM AUTHOR]

A numerical investigation into the hydrodynamic efficiency of an oscillating water column (OWC) device for the production of energy from sea waves under the conditions of regular and irregular waves is proposed. The numerical simulations were carried out using a two-dimensional version of a recently published three-dimensional free-surface nonhydrostatic numerical model, which is based on a conservative form of the contravariant Navier–Stokes equations written for a moving co-ordinate system. The governing equations are spatially discretized by a finite volume shock-capturing scheme based on high-order wave-targeted essentially nonoscillatory reconstructions and an exact Riemann solver. Time discretization was performed by a predictor-corrector method that took into account the nonhydrostatic pressure component. The proposed numerical model allowed us to highlight the significant differences between the hydrodynamic efficiency obtained under irregular waves and those obtained under regular monochromatic waves and provides more realistic evaluations of the OWC device performances. The results of the above comparison showed a reduction in the hydrodynamic efficiency of the OWC from 0.78 to about 0.54 when passing from regular waves to the corresponding irregular ones. The model was applied to assess the potential energy production obtainable by a set of OWCs at the Cetraro harbor (southern Italy). The numerical results show that, by adopting the optimal dimensions of the OWC, the estimated mean annual energy production obtainable at the Cetraro harbor is equal to 1540.52 MWh, which corresponds to the energy production of about 10 wind turbines with a nominal power of 60 KW. [ABSTRACT FROM AUTHOR]

Given the increasing global energy demand, the present study aimed to analyze the influence of bathymetry on the generation and propagation of realistic irregular waves and to geometrically optimize a wave energy converter (WEC) device of the oscillating water column (OWC) type. In essence, the OWC WEC can be defined as a partially submerged structure that is open to the sea below the free water surface (hydropneumatic chamber) and connected to a duct that is open to the atmosphere (in which the turbine is installed); its operational principle is based on the compression and decompression of air inside the hydropneumatic chamber due to incident waves, which causes an alternating air flow that drives the turbine and enables electricity generation. The computational fluid dynamics software package Fluent was used to numerically reproduce the OWC WEC according to its operational principles, with a simplification that allowed its available power to be determined, i.e., without considering the turbine. The volume of fluid (VOF) multiphase model was employed to treat the interface between the phases. The WaveMIMO methodology was used to generate realistic irregular waves mimicking those that occur on the coast of Tramandaí, Rio Grande do Sul, Brazil. The constructal design method, along with an exhaustive search technique, was employed. The degree of freedom H 1 / L (the ratio between the height and length of the hydropneumatic chamber of the OWC) was varied to maximize the available power in the device. The results showed that realistic irregular waves were adequately generated within both wave channels, with and without bathymetry, and that wave propagation in both computational domains was not significantly influenced by the wave channel bathymetry. Regarding the geometric evaluation, the optimal geometry found, H 1 / L o = 0.1985, which maximized the available hydropneumatic power, i.e., the one that yielded a power of 25.44 W, was 2.28 times more efficient than the worst case found, which had H 1 / L = 2.2789. [ABSTRACT FROM AUTHOR]

The six-degree-of-freedom (6 DOF) motion of the mother ship, especially the heave motion, brings difficulties to offshore operations and even causes safety accidents. To ensure the reliability of the launch and recovery system when the active heave compensation (AHC) function works, its dynamic characteristics are analyzed. Firstly, the dynamic model of the launch and recovery system with a rigid rope is constructed, and the mathematical simulation of the launch and recovery system without the AHC function under the excitation of irregular waves is completed. Secondly, a flexible rope based on the finite element method is established, and the dynamic responses of the launch and recovery system with AHC function under different conditions are compared with those without AHC function. The simulation results demonstrate that the dynamic responses of the system are related to the load, the underwater penetration, and the sea condition. In detail, the increase of the load leads to an increase in the dynamic response of the system. In essence, the underwater penetration affects the dynamic response of the system by affecting the activity of load acceleration. Therefore, a short rope is preferred in the maritime operations. Moreover, the harsh sea condition usually causes an undesirable effect of AHC function. In summary, the overall work is conductive to the modeling of the launch and recovery system, as well as the development of AHC technology so as to improve the quality of offshore operations in the future. [ABSTRACT FROM AUTHOR]

The propagation of shallow-water waves may cause liquefaction of the seabed, thereby reducing its support capacity for pipelines and potentially leading to pipeline settlement or deformation. To ensure the stability of buried pipelines, it is crucial to consider the excess pore pressure induced by irregular waves thoroughly. This paper presents the findings of an experimental study on excess pore pressure caused by irregular waves on a sandy seabed. A series of two-dimensional wave flume experiments investigated the excess pore pressure generated by irregular waves. Based on the experimental results, this study examined the influences of irregular wave characteristics and pipeline proximity on excess pore pressure. Using test data, the signal analysis method was employed to categorize different modes of excess pore-water pressure growth into two types and explore the mechanism underlying pore pressure development under the influence of irregular waves.

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves.

In this work, we conducted a numerical analysis of an oscillating water column (OWC) wave energy converter (WEC) device. The main objective of this research was to conduct a geometric evaluation of the device by defining an optimal configuration that maximized its available hydrodynamic power while employing realistic sea data. To achieve this objective, the WaveMIMO methodology was used. This is characterized by the conversion of realistic sea data into time series of the free surface elevation. These time series were processed and transformed into water velocity components, enabling transient velocity data to be used as boundary conditions for the generation of numerical irregular waves in the Fluent 2019 R2 software. Regular waves representative of the sea data were also generated in order to evaluate the hydrodynamic performance of the device in comparison to the realistic irregular waves. For the geometric analysis, the constructal design method was utilized. The hydropneumatic chamber volume and the total volume of the device were adopted as geometric constraints and remained constant. Three degrees of freedom (DOF) were used for this study: H1/L is the ratio between the height and length of the hydropneumatic chamber, whose values were varied, and H2/l (ratio between height and length of the turbine duct) and H3 (submergence depth of hydropneumatic chamber) were kept constant. The best performance was observed for the device geometry with H1/L= 0.1985, which presented an available hydropneumatic power Phyd of 29.63 W. This value was 4.34 times higher than the power generated by the worst geometry performance, which was 6.83 W, obtained with an H1/L value of 2.2789, and 2.49 times higher than the power obtained by the device with the same dimensions as those from the one on Pico island, which was 11.89 W. When the optimal geometry was subjected to regular waves, a Phyd of 30.50 W was encountered.

The failure of mooring lines in net cages could lead to the death or escape of farmed fish, which causes huge economic losses and immeasurable ecological impacts. Therefore, it is very important to ensure the safety of the cage mooring system in practical applications. This study experimentally and numerically investigates the hydrodynamic behaviors of the mooring line failure on a net cage in irregular waves and currents. For the model test, a 1:25 scaled net cage model with eight-point mooring is installed in a wave tank. The two load cells in its upstream mooring lines and a gyroscope on its floating collar are used to measure the mooring force and the rotational motions, respectively. A cutting device equipped with a pneumatic cylinder and a blade is used to cut the line. A self-developed numerical model is specifically established for the model test for cross-validation. Both experimental and numerical results are analyzed and compared in the time and frequency domains. The results show that the mooring load in the remaining line significantly increases as one of the upstream mooring lines is disconnected. Meanwhile, a significant yaw rotation of the floating collar is observed. The results indicate that the maximum tension, drift displacement, and rotational angles significantly increase as the current velocity increases.

This research examines the hydrodynamic performance of an oscillating water column device placed over a sloping seabed under the influence of irregular incident waves. The numerical model is based on the Reynolds-veraged Navier–Stokes (RANS) equations with a modified k − ω turbulence model and uses the volume-of-fluid (VOF) approach to monitor the air–water interface. To explore the hydrodynamic performance of the OWC device in actual ocean conditions, the Pierson–Moskowitz (P-M) spectrum was used as the incident wave spectrum, together with the four distinct sea states which occur most often along the western coast of Portugal. The numerical simulation offers a comprehensive velocity vector and streamline profiles inside the OWC device's chamber during an entire cycle of pressure fluctuation. In addition, the impact of the irregular wave conditions on the free-surface elevation at various places, the pressure drop between the chamber and the outside, and the airflow rate via the orifice per unit width of the OWC device are investigated in detail. The results demonstrate that the amplitudes of the inward and outward velocities via the orifice, free-surface elevations, and flow characteristics are greater for more significant wave heights. Further, it is noticed that the power generation and capture efficiency are higher for a seabed having moderate slopes. [ABSTRACT FROM AUTHOR]

The main goal of this research is to investigate the effect of some geometrical parameters on an onshore Hybrid Wave Energy Converter (HWEC) including an onshore Oscillating Water Column (OWC) and a Horizontal Floating Cylinder (HFC) under regular and irregular waves. The TMA spectrum is the basis of this study. The wave spectrum is used to generate irregular waves in a numerical wave tank using Ansys-fluent software based on URANS equations. Active wave absorption is used to avoid the effect of reflected waves. Also, the SST k − ω turbulence model and the VOF scheme are used for turbulence modeling and interface tracking, respectively. The results confirm that the efficiency of the HWEC is higher than the efficiency of an OWC and the efficiency of an HFC in both regular and irregular waves. Besides, the efficiency of the HWEC in irregular waves is lower than its efficiency in regular waves. A comparison of the TMA and JONSWAP spectrum on HWEC performance shows that HWEC performance is lower on the JOANSWAP spectrum. This study shows that the use of irregular waves is essential to obtain more realistic results from analyses of the onshore HWEC performance, despite their need for high computational cost. • Investigating the effect of the geometrical parameters on HWEC under regular and irregular waves. • HWEC performs better than a single OWC and HFC in regular and irregular waves. • The efficiency of HWEC in irregular waves is lower than its efficiency in regular waves. • Using irregular waves gives more realistic results of HWEC performance analysis. [ABSTRACT FROM AUTHOR]

• Developed a Computational Fluid Dynamics (CFD) based framework to predict dynamic responses of planing hulls in irregular waves, contributing to accurate seakeeping performance assessments. • Explored the effects of step configurations on planing hull responses in random waves, with a focus on hulls denoted as C, C1, and C2, revealing insights into the role of steps in mitigating vertical acceleration at different planing speeds. • Unraveling planing hull dynamics: PDF variations, Skewness and Kurtosis, Spectrum Analysis of Heave, Pitch, and center of Gravity Acceleration explored for random wave conditions. Predicting the dynamic responses of planing hulls in real sea conditions is important for identifying how basic design factors influence their seakeeping performance. Hence, there is a pressing need to provide high-fidelity models for predicting the motions of these hulls in random waves, representing actual seas. In this article, a computational-based model for solving viscous fluid flow around the vessel is built to address this problem. Three different planing hulls, denoted as C, C1, and C2, each distinguished by the number of steps incorporated on their bottom surfaces (1 and 2 indicating the respective step count, with case C being the stepless hull), are modeled in a Computational Fluid Dynamics (CFD) tank, allowing for analysis of the effects of steps on dynamic responses of a planing surface operating in random waves. CFD data is compared against those collected in towing tank tests, revealing a satisfactory level of accuracy. Extreme value and gamma distributions are shown to give probabilities of maxima/minima of displacements and vertical acceleration at the center of gravity (CG) for all three hulls. It is shown that the stepless boat may be exposed to lower vertical acceleration at an early planing speed, but at higher planing speeds, a double-stepped design mitigates the vertical acceleration. Nevertheless, the double-stepped hull would experience more significant extreme heave responses across all speeds and may be exposed to less significant extreme pitch responses during the ride at the highest speed compared to the stepless and one-stepped hulls. The skewness of heave and pitch is evaluated, and it is found that the heave response tends to skew toward positive values (upward). This skewness becomes more noticeable with increasing speed but remains insensitive to wave steepness. Additionally, the pitch response at lower planing speeds shows a partial skew towards negative values (bow-down), but eventually, they may also be partially skewed towards positive values at higher speeds. Moreover, a correlation is observed between the kurtosis of responses of different hulls and the occurrence of the 1/100 highest responses, indicating that a kurtosis greater than 3.0 would result in more extreme responses. Overall, this analysis offers practical insights into planing hull behavior in actual sea conditions from a CFD model perspective, highlighting the potential of CFD in simulating this complex problem. [ABSTRACT FROM AUTHOR]

This study presents novel analytical solutions for analyzing wave dissipation effect and bottom flow field characteristics of permeable submerged horizontal plates through physical model trials. The experimental results show that a solid submerged horizontal plate effectively attenuates wave cycles, with a greater periodic attenuation effect at smaller submerged depths. However, this attenuation effect becomes reduced or less pronounced after a certain threshold. Selecting an optimal opening ratio becomes key to achieving the desired cycle attenuation. When the inundation depth of the horizontal plate is large, the wave dissipation effect is weak. Reducing the opening rate can improve the wave dissipation effect, but only to a certain extent. Under irregular wave actions, the velocity field of the submerged horizontal plate is uniformly distributed. The relative submerged depth has minimal effect on the maximum flow velocity and root mean square flow velocity. Increasing the wave height and increasing the open holes on a plate can improve the flow velocity at the bottom of the plate. However, increasing the opening ratio also leads to insignificant changes in flow velocity. A correlation between the transmission coefficient of the open plate and the maximum flow velocity has also been determined. The findings of this paper serve as a research foundation for the implementation of submerged horizontal plate wave dissipation structures in engineering.

The simulation of wave propagation and penetration inside ports and coastal areas is of paramount importance to engineers and scientists desiring to obtain an accurate representation of the wave field. However, this is often a rather daunting task due to the complexity of the processes that need to be resolved, as well as the demanding levels of required computational resources. In the present paper, the enhancements made on an existing sophisticated Boussinesq-type wave model, concerning the accurate generation of irregular multidirectional waves, as well as an empirical methodology to calculate wave overtopping discharges, are presented. The model was extensively validated against 4 experimental test cases, covering a wide range of applications, namely wave propagation over a shoal, wave penetration in ports through a breakwater gap, wave breaking on a plane sloping beach, and wave overtopping behind breakwaters. Good agreement of the model results with all experimental measurements was achieved, rendering the wave model a valuable tool in real-life applications for engineers and scientists desiring to obtain accurate solutions of the wave field in wave basins and complex coastal areas, while keeping computational times at reasonable levels.

Ocean waves offer an uninterrupted, rich resource of globally available renewable energy. However, because of their high cost and low power production, commercial wave energy converters are not operational at present. In this paper, we numerically evaluated the performance of a novel feedback-controlled lift-based cycloidal wave energy converter (CycWEC) at various sea states of the Humboldt Bay wave climate. The device comprised of two hydrofoils attached eccentrically to a shaft at a radius, submerged at a distance under the ocean surface. The pitch of the blades was feedback-controlled based on estimation of the incoming wave. The simulations were performed for regular waves and irregular waves approximated with a JONSWAP spectrum. Climate data from Humboldt Bay, CA was used to estimate the yearly power generation. The results underline the importance of a well-tuned control algorithm to maximize the annual energy production. The estimated annual energy production of the CycWEC was 3000MWh from regular wave simulations and 1800MWh from irregular wave simulations, showing that it can be a commercially viable means of electricity production from ocean waves.

Either potential flow or viscous flow based model may be flawed for numerical wave simulations. The two-way coupling of potential and viscous flow models with the domain decomposition utilizing respective strengths has been a trending research topic. In contrast to existing literatures in which closed source potential models were used, the widely used open source OceanWave3D, OpenFOAM-v2012 are used in the present research. An innovative overlapping two-way coupling strategy is developed utilizing the ghost points in OceanWave3D. To guarantee computational stability, a relaxation zone used both for outlet damping and data transfer is built over the overlapping region in OceanWave3D. The free surface elevation in the relaxation zone is directly probed in OpenFOAM while the velocity potential is indirectly built upon its temporal variation which is calculated by the free surface boundary condition using the probed velocity. Strong coupling is achieved based on the fourth-order Runge-Kutta (RK) algorithm. Both two- and three-dimensional tests including linear, nonlinear, irregular, and multi-directional irregular waves, are conducted. The effectiveness of the coupling procedure in bidirectional data transfer is fully demonstrated, and the model is validated to be accurate and efficient, thus providing a competitive alternative for ocean wave simulations. [ABSTRACT FROM AUTHOR]

Because of their wide resonant frequency bandwidth which extends to the lower range of wave frequencies, the research community has recently paid significant attention to the design and performance analysis of bi-stable point wave energy absorbers (PWAs). Along this line, we dedicate this study to shed more light onto the behavior of bi-stable PWAs under random wave excitations. We use Monte Carlo simulations to study the effect of the wave spectral content on the statistical response of the absorber; mainly the average output power and the average capture width ratio (CWR), for different shapes of the potential energy function of the absorber. We show that there is a direct correlation between the stochastic response of the absorber and its steady-state behavior under harmonic wave excitations. In particular, we show that the PWA exhibits its best performance when the peak frequency of the waves' spectral density function is tuned to the center of the steady-state effective bandwidth of the absorber, where large-amplitude inter-well oscillations of the buoy are uniquely realized. We develop design maps to demonstrate how the CWR of the bi-stable PWA varies with the peak frequency and significant height of the waves. We use those maps to demonstrate how to design the shape of the potential energy function of the absorber to maximize the CWR for waves of known spectral content. We believe that such understanding is vital to design effective bi-stable PWAs. [ABSTRACT FROM AUTHOR]

Damping is unavoidable for the response of a ship's roll motion in waves. The roll motion of ships is represented as a second-order nonlinear differential equation that includes a nonlinear notation related to damping and restoring moments. In this paper, a new HPM process is implemented to address this real-time problem. Simple and closed-form analytical representations of the ship's roll motion and other physical properties have been generated. The results of the numerical simulation were compared to those of the analytical results. It is mentioned that there is satisfactory agreement. [ABSTRACT FROM AUTHOR]

In this paper, three curved floating bridge concepts with a uniform span of 500 m and different radii of curvature are proposed for the crossing of the coastal waters in Singapore. The bridge girder is supported by 4 pontoons along the bridge length and the two ends are connected to the shore. Three different girder cross-sections are considered. Static analysis is first carried out considering the bridge's self-weight, water current forces and various tidal conditions. Next, eigen value and regular wave analyses are performed to assess the effect of bridge radius, cross-sectional rigidity and end connection on the bridge behaviour. Based on the results, several bridge configurations are selected for further study. Finally, irregular wave analysis is carried out to investigate the realistic bridge performance under operational and extreme environmental conditions. Conclusions are drawn based on the simulation results. Recommendations on the design parameters for further investigations are made. [ABSTRACT FROM AUTHOR]

Most existing studies are based on the hydroelastic response of oversized floating bodies under regular waves, ignoring the effect of wave conditions and incident wave angle on the vibration response of oversized floating bodies in real sea conditions. In this paper, the stability performance of a single module of a mega-floating body at an offshore airport was investigated by using STAR-CCM + numerical simulations based on a specific model, with the introduction of parameters under extreme random wind and wave combined sea conditions. By comparing and analyzing the distribution characteristics of the single module floating body under the action of regular waves and irregular waves, wind, and wave load, and by considering the wave angle along the flow direction, as well as the spreading direction and vertical displacement value under the action of mooring, the overall displacement amplitude of rigid displacement, elastic deformation displacement and considering the influence of both, and the distribution law of motion response along the length of the floating body, we summarize the influence of the wave angle on the dynamic response of an oversized floating body of an offshore airport. The results show that the maximum value of the hydro-elastic response tends to appear at the head and tail of the floating body, the rigid body vertical displacement dominates the role, the amplitude of all displacements of the floating body under the action of the cross wave is larger, and the stress area along the floating body is larger when the wave angle is between 15–30°. The floating body stress value is smaller with angles of 30–65°, and the ability to bear the load is stronger. The hydroelastic response under irregular wave conditions is more sensitive to the wave direction angle, and the elastic deformation has less influence. [ABSTRACT FROM AUTHOR]

This paper presents a methodology that allows the numerical simulation of realistic sea waves, called WaveMIMO methodology, which is based on the imposition of transient discrete data as prescribed velocity on a finite volume computational model developed in Fluent software. These transient data are obtained by using the spectral wave model TOMAWAC, where the wave spectrum is converted into a series of free surface elevations treated and processed as wave propagation velocities in the horizontal (x) and vertical (z) directions. The processed discrete transient data of wave propagation velocity are imposed as boundary conditions of a wave channel in Fluent, allowing the numerical simulation of irregular waves with realistic characteristics. From a case study that reproduces the sea state occurring on March 31st, 2014, in Ingleses Beach, in the city of Florianópolis, state of Santa Catarina, Brazil, it was concluded that the WaveMIMO methodology can properly reproduce realistic conditions of a sea state. In sequence, the proposed methodology was employed to numerically simulate the incidence of irregular realistic waves over an oscillating water column (OWC) wave energy converter (WEC). From these results, the WaveMIMO methodology has proved to be a promising technique to numerically analyze the fluid-dynamic behavior of WECs subjected to irregular waves of realistic sea state on any coastal region where the device can be installed.

A variety of floating structures at sea play a vital role in the exploitation and utilization of marine resources. The study about interactions between waves and structures is necessary for the impact of the harsh marine environment on the motion and service life of structures. Currently, most studies about the seakeeping of structures are based on simplified regular waves. Because the regular waves do not truly restore the actual wave conditions at sea, the simulation of irregular waves has great practical importance to the study of interactions between waves and structures. Based on the potential flow theory and high-order boundary element method (HOBEM), a Fortran code is developed in this paper and named as SWBI (Solver for Wave–Body Interactions). This program consists of the following two parts: a time–domain numerical model about interactions between waves and 3D structures is based on weakly nonlinear method, and a numerical model about simulation of the nonlinear regular waves, the long-crested irregular waves, and the short-crested irregular waves. This Fortran code is used to simulate the motion of Floating Production Storage and Offloading (FPSO) under three different ocean wave spectra (including ITTC two-parameters spectrum, JONSWAP spectrum and the most likely spectral form of Ochi-Hubble) and found that: To a certain extent, the difference in the motion of FPSO under different wave spectra have a connection with different type of wave, sea conditions and incident angle. The difference in roll of FPSO is quite significant in short-crested irregular waves. The range of FPOS’s roll under the JONSWAP spectrum is the largest when the incident angle is 30°, and range of FPOS’s roll under the most likely spectral form of Ochi-Hubble is the largest when the incident angle is 90°.

Wave breaking is widely recognized as a very challenging phenomenon to emulate using numerical/computational methods. On that condition, the transition from modelling regular to irregular breaking waves is not trivial. Even though some issues are surpassed in CFD simulations, there still are two substantial problems to account for. The first one entails the proper generation of irregular waves in a numerical wave tank, while the second is the introduction of the turbulent regime of breaking in the solver. The present work addresses these two problems by employing the Stabilized k − ω SST model for turbulence closure and by proposing an efficient and accurate method for irregular wave generation. Apart from that, an artificial compressibility method is used for coupling the system of equations, which solves these equations in a non-segregated manner and overcomes problems pertaining to the existence of the interface in free-surface flows. The methodology is validated through the test case of irregular wave propagation over a submerged breaker bar and a piecewise sloped bottom, indicating the ability of the method to capture irregular breaking wave phenomena. Simulations are in fair agreement with experimental data regarding energy spectra and free surface time-series, while results suggest that the known over-prediction of turbulent kinetic energy (TKE) is significantly constrained by the stabilized k − ω SST model. [ABSTRACT FROM AUTHOR]

This paper describes the design and execution of a wavemaker system (piston type) in the Dokuz Eylül University Hydraulic Laboratory flume to perform hydraulic model tests using regular and irregular waves. In this study, we will focus on generating the irregular waves from the target JONSWAP spectrum using an adjusted random phase method; also, the control software of the wavemaker is described. An identical numerical channel wave to the physical flume was modeled to compare and observe the irregular wave profile using Flow 3D, one of the advanced computational fluid dynamics (CFD) software. The paddle movement was validated by comparing the experimentally converted irregular wave surface elevations to the wave spectrum to the numerical models of several waves. [ABSTRACT FROM AUTHOR]

In deep-sea mining operations, the mining riser is the most fragile and technologically demanding segment of the entire system. It is crucial to investigate the dynamic response and fatigue characteristics of mining risers to elucidate their motion patterns and fatigue mechanisms. In this study, we examine the vibration behavior of the deep-sea mining riser using the time-domain finite element method under various sea conditions and estimate the fatigue life of the mining riser based on the Miner-Palmgren damage rule. Results indicate that the significant wave height and peak period of irregular waves significantly influence the dynamic response characteristics and fatigue damage properties of the riser. The axial displacement, rotation angle, bending moment, effective tension, and von Mises stress of the riser are maximized and minimized at the top and bottom, respectively, whereas the lateral displacement shows the opposite trend. In general, the axial displacement exhibits a more complex pattern than the lateral displacement, and the maximum fatigue damage is predominantly concentrated in the middle and upper sections of the riser. • Dynamic behaviors of a deep-sea mining riser under various sea conditions are investigated. • The axial compared with lateral displacements of the riser demonstrate a more intricate pattern of behavior. • The motion trajectory and frequency of the buffer station of the mining riser are ascertained. • The dynamic stress levels and fatigue distribution along the mining riser affected by the irregular waves are given. [ABSTRACT FROM AUTHOR]

Finding sustainable and infinite green energy options in a world that relies primarily on fossil fuels is crucial as traditional sources decline. Wave energy is an excellent example of an environmentally friendly power source. A multi-utility bio-inspired floating device consisting of two TSUSUCA (TSUnami Protection Solar Utilization and other Coastal Applications) Dolphin-shaped bodies integrated with a linear motion electricity generator (LMEG) connected to a rigid deck by a hinged connection is tested experimentally under irregular waves. This novel and innovative multi-utility floating offshore device can function as a tsunami barrier and a wave energy extraction device. Its performance and operating mechanism are investigated under 8 different sets of irregular waves. The examined sea states are represented by JONSWAP and PM wave spectra with a range of significant wave heights (0.05–0.20 m) and peak periods (1.5 and 2.0 s). The experimental results show that the overall electrical power efficiency of LMEG coupled to each Dolphin obtained for set 6 is 32.04 % and 30.81 % for both JONSWAP and PM spectrums, respectively. This bio-inspired device and its performance confirms the proof-of-concept while the presented study shall become a prime factor towards the development of more similar devices to harness wave energy. • A bio-inspired floating platform is proposed for tsunami protection and energy harnessing. • The concept is supported by detailed numerical investigations, as proof-of-concept. • Detailed experimental studies are useful to examine overall efficiency of device. [ABSTRACT FROM AUTHOR]

The dynamic structural response of a vertical pile port platform under the action of irregular wave loads considering soil-structure interaction is studied. Deck displacement and bending moment on the piles were evaluated for a set of structural, hydraulic, and geotechnical parameters. Static structural analyses with the maximum base shear produced by wave loads and dynamic time-history analyses are performed to study the effects of dynamic amplification on the structural response of the platform. Two types of waves are analyzed, regular and irregular, to analyze the amplification effects due to the superposition of a wave train of different periods in the case of irregular waves. Cases with fixed base support and non-linear spring-modeled soil are considered to evaluate the effect of considering a flexible base for the platform. Eight structures composed of a different number of piles and with different heights were analyzed. Six wave conditions with different characteristics are used, varying the wave period and mean water height. Two sandy and two clayey soil profiles are considered with different densities and consistency. The results show that resonance effects associated with dynamic loading and small-period wave superposition in cases of irregular waves significantly affect the response. Furthermore, considering a flexible base tends to decrease the response for short wave periods, concluding that, in most cases, for wave periods close to 5 s, considering a fixed base model overestimates the response. • A transparent port platform with vertical piles under wave loads is studied. • Effects of dynamic loading, irregular waves and flexible base modeling are analyzed. • Resonance effects are not represented in a study with regular waves. • Resonance effects due to dynamic loading and irregular waves are significant in the displacement and bending moment response. • The use of a fixed base overestimates the bending moment response of the structure. [ABSTRACT FROM AUTHOR]

The growing implementation of Decision Support Systems on modern ships, digital-twin technology, and the introduction of autonomous vessels cause the marine industry to seek accurate modeling of vessel response. Despite the contemporary 6DOF models can be used to predict ship motions in irregular waves, the impact of their stochastic realization is usually neglected and remains under-investigated. Especially in the case of turning, differences arising from the stochastic representation of the waves may result in excessive ship motions or even stability failure during maneuver execution. Therefore, in this study, statistical distributions of maximum amplitudes of roll, pitch, and lateral acceleration calculated in two representative locations on board a passenger vessel were analyzed concerning stochastic wave realization and existing extremes. The research utilized 6DOF simulation data and numerous realizations of the irregular wave with random phases of its components. Furthermore, the required number of wave realizations allowing for capturing the actual ranges of ship response at an assumed confidence level has been determined and analyzed. Ultimately, the results were compared in the safety-critical cases concerning various wave and operational conditions. The outcome of this study may be found useful by all parties involved in developing maritime autonomous systems and modeling ship motions. • The impact of stochastic wave realizations on a passenger ship's response is investigated for turning maneuver. • The ship motion parameters, i.e., the maximum amplitude of roll, pitch, and lateral accelerations are analyzed. • The realizations of irregular waves are investigated concerning various environmental and operational conditions. • The simulation-based approach is utilized to determine the required number of wave realizations. • The factors influencing minimum sample size with regard to wave stochastics are investigated. [ABSTRACT FROM AUTHOR]

Aquaculture cages located in offshore areas typically contain frames and flexible nets. The cages are typically subjected to irregular waves and the frames may deform irregularly over time. Since the nets are tied on the frames, when the frames deform over time, the boundaries of the nets change. In this study, a large flexible net subjected to irregular waves and irregular boundary deformations is theoretically simulated. The irregular waves are simulated using the modified Jonswap spectrum, while the irregular boundary deformations are described by superimposing a series of cosine functions that follow a Gaussian distribution. The dynamic responses of a flexible net are solved numerically. The proposed model is validated by comparison with experimental results. When the boundaries of the net irregularly deformed in the vertical direction, the vibrations of the net in the vertical direction are significantly affected, while the vibrations in the horizontal direction are slightly affected, which are mainly dominated by irregular waves. • A large flexible net simultaneously excited by irregular waves and irregular boundary deformations is simulated. • The boundaries deflecting irregularly are described by summing many cosine functions, which follows Gaussian distribution. • The vibrations of the net in the horizontal direction are mainly caused by irregular waves. • When the boundaries deflect irregularly in the vertical direction with larger amplitudes, the net is more easily broken. [ABSTRACT FROM AUTHOR]

In times of progressive automation of the marine industry, accurate modeling of ship maneuvers is of utmost importance to all parties involved in maritime transportation. Despite the existence of modern collision-avoidance algorithms using 6DOF motion models to predict ship trajectories in waves, the impact of stochastic realization of irregular waves is usually neglected and remains under-investigated. Therefore, herein, this phenomenon and its impact were investigated in the case study of the passenger ship's turning. To this end, statistical and spatiotemporal distributions of ship positions and corresponding trajectory parameters were analyzed. This was made using massive 6DOF simulation data with particular attention to the observed extremes. Additionally, the minimum number of wave realizations has been determined using different methods in various simulation scenarios and afterward compared concerning parameters' impact and existing dependencies. The results indicate that for simulated scenarios, the required number of wave realizations should be at least 20, but in rough seas should be greater than 30. These values satisfy an acceptable and operationally reasonable error limit reaching 15% of the ship's length overall. The obtained results may be of interest to autonomous ship developers, scholars, and marine industry representatives working on intelligent collision-avoidance solutions and ship maneuvering models. • The impact of stochastic realizations of irregular waves is investigated for the case of ship turning. • The turning circle parameters (advance, transfer, tactical diameter, max drift distance) are analyzed. • The wave realizations are analyzed concerning various environmental and operational conditions. • The bootstrap-inspired simulation method is proposed to determine the minimum sample size. • The minimum number of wave realizations is determined and analyzed for various simulation scenarios. [ABSTRACT FROM AUTHOR]

A numerical investigation into the hydrodynamic efficiency of an oscillating water column (OWC) device for the production of energy from sea waves under the conditions of regular and irregular waves is proposed. The numerical simulations were carried out using a two-dimensional version of a recently published three-dimensional free-surface nonhydrostatic numerical model, which is based on a conservative form of the contravariant Navier–Stokes equations written for a moving co-ordinate system. The governing equations are spatially discretized by a finite volume shock-capturing scheme based on high-order wave-targeted essentially nonoscillatory reconstructions and an exact Riemann solver. Time discretization was performed by a predictor-corrector method that took into account the nonhydrostatic pressure component. The proposed numerical model allowed us to highlight the significant differences between the hydrodynamic efficiency obtained under irregular waves and those obtained under regular monochromatic waves and provides more realistic evaluations of the OWC device performances. The results of the above comparison showed a reduction in the hydrodynamic efficiency of the OWC from 0.78 to about 0.54 when passing from regular waves to the corresponding irregular ones. The model was applied to assess the potential energy production obtainable by a set of OWCs at the Cetraro harbor (southern Italy). The numerical results show that, by adopting the optimal dimensions of the OWC, the estimated mean annual energy production obtainable at the Cetraro harbor is equal to 1540.52 MWh, which corresponds to the energy production of about 10 wind turbines with a nominal power of 60 KW.

This paper presents the power generation from point absorber wave energy converters (WEC) when they are placed in a moonpool. Due to the effect of resonance in the moonpool and the hydrodynamic interaction between the arrays of WECs, the energy generation from the arrays of WECs could be increased significantly under their optimal design consideration. The arrays of different numbers of WECs, i.e., one, five and 21 are considered in the study, where the performance of the WECs in a moonpool is presented and the wave elevation surrounding the array of WECs is shown. The research finding shows that the power generated by the arrays can be significantly enhanced when the wave period is greater than 8s by deploying five-WEC in a 30-m diameter moonpool with draft greater than 1m. With the ideal design condition established, the multiple arrays of five WECs arranged in a 2 × 1 array and 2 × 2 array configurations, are placed in the moonpool and subjected to regular and irregular waves to study the possibility of further energy generation enhancement with increased numbers of arrays. [ABSTRACT FROM AUTHOR]

The propagation of nonlinear water waves under complex wave conditions is the key issue of hydrodynamics both in coastal and ocean engineering, which is significant in the prediction of strongly nonlinear phenomena regarding wave–structure interactions. In the present study, the meshless generalized finite difference method (GFDM) together with the second-order Runge–Kutta method (RKM2) is employed to construct a fully three-dimensional (3D) meshless numerical wave flume (NWF). Three numerical examples, i.e., the propagation of freak waves, irregular waves and focused waves, are implemented to verify the accuracy and stability of the developed 3D GFDM model. The results show that the present numerical model possesses good performance in the simulation of nonlinear water waves and suggest that the 3D "RKM2-GFDM" meshless scheme can be adopted to further simulate more complex nonlinear problems regarding wave–structure interactions in ocean engineering. [ABSTRACT FROM AUTHOR]

Using the stochastic averaging method, the probability density function (PDF) of roll motion for parametric rolling in irregular waves is obtained. In this paper, the stochastic averaging method using Hamiltonian proposed by Dostal is used, and the PDF of roll amplitude and Hamiltonian are derived from the equations of roll motion. In addition, the asymptotic behavior of PDF is investigated to improve the accuracy of the calculation. Furthermore, to improve the applicability of this method, the simulation-based stochastic method is proposed. Compared to the results of the stochastic averaging method proposed by Roberts and Dostal, the results using this improved method show a good agreement. The results are examined for parametric excitation using white noise as well as colored noise. Moreover, the relationship between the scale parameter and the PDF is theoretically analyzed and formulated. [ABSTRACT FROM AUTHOR]

This study concerns the preliminary seakeeping analysis of a river barge of 3000 T with a length of 90 m and two main loading conditions: full cargo and ballast. As environmental conditions, the maximum wave height is 2 m, with a whole range wave-barge heading angle, specific for all the river navigation zone. The maximum speed of the river barge is 15 km/h. The numerical analysis involves a linear seakeeping code by strip-theory method and short-term irregular waves approach, representing a preliminary simplified evaluation of the navigation capabilities of the river barge. [ABSTRACT FROM AUTHOR]

This study investigated the interaction between irregular waves and vertical breakwater. The main goal was to determine the wave force on the breakwater for different depths, along with the evolution of the secondary wave generated by overtopping. The open source code DualSPHysics was used in the simulation. Wavelet transform was employed to remove the acoustic components from the weakly compressible smoothed particle hydrodynamics pressure solution. The results of the experiments and simulations showed that although the wave height at the low water level (case 2) was smaller than that at the high water level (case 1), the horizontal and uplifting force of case 2 was higher than that of case 1. In case 2, a large impact pressure occurred because of the plunging wave and wave breaking effects. As the water level was close to the breakwater top in case 1, the secondary wave generated by overtopping was studied. Results indicated that wave and breakwater interactions transfer wave energy from the leading wave component to higher harmonics. Two main harmonics were identified in the secondary wave. The first harmonic was the incident peak frequency, which was still the dominant component. During the wave propagation behind the breakwater, the frequencies of harmonics remained unchanged, but the amplitude of the first harmonic showed an obvious change. Under the same wave condition, the first and second harmonics did not change with depth. [ABSTRACT FROM AUTHOR]