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The wave force on the deck at the connection between the bridge and the revetment is complicated. The current port or bridge engineering specifications at home and abroad only provide the formula for calculating the wave force on the deck of the offshore structure when the normal wave is incident, but do not take into account the influence of the oblique wave incident and the impact of the revetment on the wave force of deck. Taking a cross-sea bridge project in Xiamen as an example, the physical model test is carried out to study the wave force on deck at the connection between the bridge and the vertical revetment under the action of oblique waves and the distribution of wave pressure. The results show that for the shore-connecting bridge deck, the maximum wave uplift force on the deck under the action of oblique waves is greater than the maximum uplift force under the action of normal waves, which is about 3 times. When the oblique wave propagates to the vertical revetment, the wave reflects by the revetment and the wave height increases, the wave pressure at the bottom of the shore-connecting bridge deck increases significantly, and the pressure gradually decreases from the connection side to the offshore side. The applicability of each wave force formula is analyzed by comparing the measured results of physical model with the calculated results of calculation method, which provides basis and reference for engineering design. [ABSTRACT FROM AUTHOR]

Large waves cause a great number of collapsed-ship accidents, resulting in the loss of many lives and properties. It has been found that most of these collapses are caused by encountering oblique waves. As a result, the ship structure experiences a complex collapse under combined bending and torsion. This paper utilizes a numerical hydroelasto-plastic approach, coupling CFD (Computational Fluid Dynamics) with the nonlinear FEM (Finite-Element Method), to study the structural collapse of a containership in oblique waves. First, a 4600 TEU containership was selected to study its collapse mechanism under oblique waves. Second, a hydroelasto-plastic numerical coupling of CFD and nonlinear FEM is used to co-calculate the wave loads and structural collapse of containership. The hydrodynamic model is constructed and used to solve wave loads in the CFD solver, and a nonlinear FEM model of containership with finer meshes is also modeled to solve the structural collapses, including plasticity and buckling. Third, several oblique-wave cases involving heading angles of 120°, 135°, 150°, and 180° are determined and calculated. Typical cases are discussed for time-domain stress histories and collapsed courses. Finally, the influence of oblique-wave parameters on structural collapse is discussed, and the collapse mechanism of containerships under the action of oblique waves is obtained, which provides a new understanding of ship structure design. [ABSTRACT FROM AUTHOR]

Slope stability formulae for rubble mound structures are usually developed for head-on conditions. Often, the effects of oblique waves are neglected, mainly because it is assumed that for oblique wave attack, the reduction in damage compared to perpendicular wave attack is insignificant. When the incident waves are oblique, the required armour size can be reduced compared to the perpendicular wave attack case. Therefore, it is important to consider the wave obliquity influence on slope stability formulae as a reduction factor. One of the most recent formulae for estimating the stability of rock-armoured slopes, referred to as Etemad-Shahidi et al. (2020), was proposed for perpendicular wave attack. The aim of this study is to develop a suitable wave obliquity reduction factor for the above-mentioned stability formula. To achieve this, first, laboratory experiment datasets from existing reliable studies were selected and analysed. Then, previously suggested reduction factors were evaluated and a suitable reduction factor for the mentioned stability formula were suggested. The suggested reduction factor includes the effect of wave obliquity and directional spreading explicitly. It is shown that the stability prediction is improved by using the wave obliquity reduction factor. [ABSTRACT FROM AUTHOR]

A theoretical analysis involving surface gravity waves propagation by oblique incidence wave due to a thin elastic plate submerged in finite depth water in the presence of ice cover has been studied extensively in this paper employing Green's function technique. The edges of the elastic plate are considered to be free. The boundary conditions on the elastic plate and on the ice cover are derived from the Bernoulli–Euler's beam equation. Applying Green's function technique, the boundary condition satisfied on the elastic plate is converted into integral involving the difference in velocity potentials (unknown) across the plate multiplied by an appropriate Green's function. Utilizing Green's integral theorem, the reflection and transmission energy coefficients are explained in terms of integrals involving combinations of the unknown velocity potential on the two sides of the plate, which satisfy three simultaneous integral equations and are solved numerically. The effect of different values of physical parameters, such as flexural rigidity of ice, elastic coefficient of the barrier, and height and depth of the barrier, on the numerical assessment of magnitude of reflection and transmission coefficients is explained graphically in a number of figures. The energy balance relation is satisfied numerically. The results for a rigid plate are recovered when the parameters characterizing the elastic plate are chosen negligibly small. The influence of ice cover is clearly shown in the behavior of reflection and transmission coefficients curves. The hydrodynamic force, elastic plate deflection, shear force, and shear strain of the elastic plate are analyzed and computed analytically and graphically in a number of figures to understand the effect of ice cover on the wave motion. [ABSTRACT FROM AUTHOR]

In this paper, the CFD-FEM two-way coupled method is extended to simulate the asymmetric motions and wave load responses of a ship in oblique regular waves considering hydroelasticity effects. The numerical results of ship motions and loads including time series and response amplitude operators are validated by comparing with the tank experimental results. Then the ship motions, vertical bending moment, horizontal bending moment and torsion moment in oblique waves are analyzed in both time domain and frequency spectra; and the influence of wave height, wave length and ship speed on the results are systematically analyzed. Moreover, the correlation between horizontal bending moment and torsion moment as well as their component loads is analyzed by cross-spectral analysis method. The effect of springing responses corresponding to the bending-torsion coupled mode on the sectional loads is also discussed. • A CFD-FEM method is used to study ship asymmetric motions and loads in oblique regular waves. • Bending-torsion coupling loads of ship in oblique waves are studied. • Correlation between horizontal bending moment and torsion moment is analyzed by cross-spectral method. [ABSTRACT FROM AUTHOR]

Large waves cause a great number of collapsed-ship accidents, resulting in the loss of many lives and properties. It has been found that most of these collapses are caused by encountering oblique waves. As a result, the ship structure experiences a complex collapse under combined bending and torsion. This paper utilizes a numerical hydroelasto-plastic approach, coupling CFD (Computational Fluid Dynamics) with the nonlinear FEM (Finite-Element Method), to study the structural collapse of a containership in oblique waves. First, a 4600 TEU containership was selected to study its collapse mechanism under oblique waves. Second, a hydroelasto-plastic numerical coupling of CFD and nonlinear FEM is used to co-calculate the wave loads and structural collapse of containership. The hydrodynamic model is constructed and used to solve wave loads in the CFD solver, and a nonlinear FEM model of containership with finer meshes is also modeled to solve the structural collapses, including plasticity and buckling. Third, several oblique-wave cases involving heading angles of 120°, 135°, 150°, and 180° are determined and calculated. Typical cases are discussed for time-domain stress histories and collapsed courses. Finally, the influence of oblique-wave parameters on structural collapse is discussed, and the collapse mechanism of containerships under the action of oblique waves is obtained, which provides a new understanding of ship structure design.

Based on the failure and instability of different structural transitions of offshore breakwater, this paper provides a basis for understanding the instability mechanism and also provides suggestions for engineering repair. Based on the breakwater project in the regulation of the bay of Shandong Province, physical model tests with a scale of 1:36 were carried out. This study revealed the wave characteristics, the force performance, and the instability mechanism in the transition. In the test, the relationships between 5°, 15°, 35°, and 75° oblique waves, the wave force, and the stable weight of the Accropode were simulated, revealing that the generation of a shock wave current is related to the wave direction angle, which results in the local wave height increasing by 2.05 times. The result that the design weight of the armour block is unstable and stable after optimization is obtained. The wave force of the caisson of the transition was concentrated in the anti-arc section of the superstructure, and the maximum horizontal force, buoyancy force, and impact pressure were 935.6 kN, 419.1 kN, and 65.9 kPa, respectively. The instability mechanism was determined as the poor connection between the accropode and the caisson, and the wave energy concentration. Compared with the calculation results of the standard formula, the correction coefficients of the overtopping volume, the wave crest elevation, the wave force, and the Accropode weight at the transition of breakwater were 1.95, 1.97, 1.60, and 4.0, respectively. The test results have solved the practical problems of the project and can also provide a reference for similar projects. [ABSTRACT FROM AUTHOR]

In this paper, the global motions and wave loads on a large bow-flare ship in oblique regular waves considering hydroelastic effects are studied both numerically and experimentally. Numerical simulations of the ship's asymmetrical motions and loads in waves are conducted using a CFD-FEM two-way coupled method. The segmented model tank test is also conducted by using a hybrid structural backbone beam to measure both the sectional vertical bending moment and torsional moment. The numerical results are verified and validated by analyzing the ship modal behaviour, roll free decay curve, motions and loads and comparing with the experiment results. The influence of wave heading angle, wave length, wave height and ship speed on the wave loads including sectional bending moment and torsion moment are comprehensively studied with the numerical and experimental results. The relationship among vertical bending moment, horizontal bending moment and torsion moment is also discussed. [ABSTRACT FROM AUTHOR]

This work investigates the interactions between oblique waves and a partially immersed double baffle. An analytical solution to this problem, based on the linear potential flow theory, has been found by utilizing the eigenfunction matching method. The resonance issues between the double baffle under the action of oblique waves is primarily investigated using this model, considering various relative widths, 2B/L (2 B is the distance between the two baffles, L is the wave length), and the relative submergence, kD (k is the wavenumber, D is the submergence of the baffles). When resonance occurs, the transmission coefficient will rapidly increase to 1. By analyzing the relationship between the transmission coefficient and the relative width 2B/L, it is found that there are different resonance points and modes. The resonance points and modes depend on the submergence of baffles kD. This study provides a formula for calculating the resonance points. For a normal incident wave, when kD is below 1.0, the 1st-order resonance occurs in the small 2B/L region, resulting in a piston motion. High-order modes exhibit different forms, with standing waves occurring for kD ≥ 0.8, progressive waves for kD ≤ 0.48, and resonant modes ranging between standing and progressive waves for 0.48 < kD < 0.8. The effects of the incident angle on the resonance point and mode under oblique waves have also been investigated. The incident angle wave affects the interval between the two neighboring resonance points, which increases to 1/cos α times of the normal incidence for an angle of α. The resonance motion under oblique waves is nearly identical to that under the normal incident waves in the transverse plane. The difference is that there is a progressive wave in the longitudinal plane under the action of oblique waves. • Due to the resonance phenomenon, the transmission coefficient periodically changes abruptly to 1 as 2B/L increases. • The submergence of double baffles kD is the key factor that affects the resonance. • The interval of higher-order resonance points is approximately equal to half of the relative width. • The first-order resonance mode is piston motion. [ABSTRACT FROM AUTHOR]

Simply supported bridges comprise the majority of bridge systems in coastal communities and are susceptible to severe damage from extreme waves induced by storms or tsunamis. However, the effects of oblique wave impacts have been less investigated due to the lack of appropriate numerical models. To address this issue, this study investigates the effects of wave incident angles on coastal bridge superstructures by developing an advanced computational fluid dynamics (CFD) model. Different wave scenarios, including wave height, relative clearance, incident angle, and wavelength are tested. It is found that the maximum wave forces in the horizontal and longitudinal directions could reach 1901 and 862 kN under extreme conditions, respectively, destroying bearing connections. Three surrogate models, i.e., the Gaussian Kriging surrogate model, the Artificial Neural Network (ANN), and the Polynomial Chaos Expansion (PCE), are established by correlating the wave parameters with the maximum wave forces. Through comparisons among the three surrogate models, it is found that the 3-order PCE model has better performance in predicting loads in vertical and horizontal directions, while the ANN model is more suitable for results in the longitudinal direction. This study contributes to the optimized design of coastal bridges and also offers an opportunity for future studies to investigate hazard damage-mitigation measures. [ABSTRACT FROM AUTHOR]

When the ship is sailing at sea, wave added resistance has great influence on the rapidity and economy of the ship. With the increasing pressure of energy and environmental protection, IMO has proposed the EEDI formula of the newly built ships, which restricts the energy consumption standard of civil ships more strictly. Therefore, a panel method based on three dimensional potential flow theory is proposed to study the problem of wave added resistance in this paper. Firstly, the method solves the motion responses of the ship in the time domain, and then calculates the wave added resistance of the ship by near-field pressure integration method. The wave added resistance of S175 container ship in head and oblique waves are calculated and compared with the experimental data, and the accuracy of the proposed method are verified. At last, the influence of Froude number and wave direction angle on wave added resistance is studied. The proposed method provides an approach of satisfactory accuracy and efficiency for the development of high-performance new ship forms, optimization of ship hull lines, comprehensive performance evaluation of ships and practical navigation guidance. [ABSTRACT FROM AUTHOR]

Slope stability formulae for rubble mound structures are usually developed for head-on conditions. Often, the effects of oblique waves are neglected, mainly because it is assumed that for oblique wave attack, the reduction in damage compared to perpendicular wave attack is insignificant. When the incident waves are oblique, the required armour size can be reduced compared to the perpendicular wave attack case. Therefore, it is important to consider the wave obliquity influence on slope stability formulae as a reduction factor. One of the most recent formulae for estimating the stability of rock-armoured slopes, referred to as Etemad-Shahidi et al. (2020), was proposed for perpendicular wave attack. The aim of this study is to develop a suitable wave obliquity reduction factor for the above-mentioned stability formula. To achieve this, first, laboratory experiment datasets from existing reliable studies were selected and analysed. Then, previously suggested reduction factors were evaluated and a suitable reduction factor for the mentioned stability formula were suggested. The suggested reduction factor includes the effect of wave obliquity and directional spreading explicitly. It is shown that the stability prediction is improved by using the wave obliquity reduction factor.

Based on the failure and instability of different structural transitions of offshore breakwater, this paper provides a basis for understanding the instability mechanism and also provides suggestions for engineering repair. Based on the breakwater project in the regulation of the bay of Shandong Province, physical model tests with a scale of 1:36 were carried out. This study revealed the wave characteristics, the force performance, and the instability mechanism in the transition. In the test, the relationships between 5°, 15°, 35°, and 75° oblique waves, the wave force, and the stable weight of the Accropode were simulated, revealing that the generation of a shock wave current is related to the wave direction angle, which results in the local wave height increasing by 2.05 times. The result that the design weight of the armour block is unstable and stable after optimization is obtained. The wave force of the caisson of the transition was concentrated in the anti-arc section of the superstructure, and the maximum horizontal force, buoyancy force, and impact pressure were 935.6 kN, 419.1 kN, and 65.9 kPa, respectively. The instability mechanism was determined as the poor connection between the accropode and the caisson, and the wave energy concentration. Compared with the calculation results of the standard formula, the correction coefficients of the overtopping volume, the wave crest elevation, the wave force, and the Accropode weight at the transition of breakwater were 1.95, 1.97, 1.60, and 4.0, respectively. The test results have solved the practical problems of the project and can also provide a reference for similar projects.

Simply supported bridges comprise the majority of bridge systems in coastal communities and are susceptible to severe damage from extreme waves induced by storms or tsunamis. However, the effects of oblique wave impacts have been less investigated due to the lack of appropriate numerical models. To address this issue, this study investigates the effects of wave incident angles on coastal bridge superstructures by developing an advanced computational fluid dynamics (CFD) model. Different wave scenarios, including wave height, relative clearance, incident angle, and wavelength are tested. It is found that the maximum wave forces in the horizontal and longitudinal directions could reach 1901 and 862 kN under extreme conditions, respectively, destroying bearing connections. Three surrogate models, i.e., the Gaussian Kriging surrogate model, the Artificial Neural Network (ANN), and the Polynomial Chaos Expansion (PCE), are established by correlating the wave parameters with the maximum wave forces. Through comparisons among the three surrogate models, it is found that the 3-order PCE model has better performance in predicting loads in vertical and horizontal directions, while the ANN model is more suitable for results in the longitudinal direction. This study contributes to the optimized design of coastal bridges and also offers an opportunity for future studies to investigate hazard damage-mitigation measures.

Emergent buoyantly rising submarines encounter excess roll problems, partially owing to waves that significantly affect their behavior. This study predicts the behavior of a submarine, including when it rises in static water, beam sea, head wave, following wave, 30 ∘ bow wave, 60 ∘ bow wave, 30 ∘ quartering wave, and 60 ∘ quartering wave, using the computational fluid dynamics method. The beam sea has a slight effect on pitch prior to the submarine rising to the water surface, but the maximum roll angle in the beam sea is 4.43 times that in static water. After a submarine submerges in water, the pitching oscillation does not decay quickly owing to the yaw angle. The head wave and the following wave have a continuous significant effect on the pitch; the submarine sail remains under the water surface after it submerges from the highest position. The head wave and the following wave have a slight effect on the roll and yaw before the submarine rises to the water surface; however, the roll angle suddenly increases after the submarine submerges from the highest position. As the initial angle between the submarine centerline and wave direction increases, the effect of waves on the longitudinal motion decreases. The amplitude of the pitching oscillation decreases with an increase in the initial angle between the submarine centerline and wave direction, and the waterline when the submarine oscillates on the water surface decreases. The difference in the maximum roll angle between when a submarine rises in an oblique wave and when it rises in beam sea is below 6.3 ∘ . Submarines should try to avoid rising in a head wave and the following wave. [ABSTRACT FROM AUTHOR]

In this study, experimental and numerical methods were applied to estimate surge and sway wave drift forces and yaw drift moment acting on KVLCC2, advancing in oblique wave. An experiment was carried out in the ocean engineering basin of the Korea Research Institute of Ships and Ocean Engineering (KRISO). A series of regular wave tests under various heading conditions were conducted to investigate ship motion responses and wave drift forces. A Rankine panel method based on potential flow was adopted in the numerical analysis, and the direct pressure integration method that integrates second-order pressure on the hull surface was applied to compute wave drift force. Through this study, validation data of wave drift force acting on KVLCC2 was established, and the computation capability of the potential-based numerical method was systematically analyzed.

Emergent buoyantly rising submarines encounter excess roll problems, partially owing to waves that significantly affect their behavior. This study predicts the behavior of a submarine, including when it rises in static water, beam sea, head wave, following wave, 30∘ bow wave, 60∘ bow wave, 30∘ quartering wave, and 60∘ quartering wave, using the computational fluid dynamics method. The beam sea has a slight effect on pitch prior to the submarine rising to the water surface, but the maximum roll angle in the beam sea is 4.43 times that in static water. After a submarine submerges in water, the pitching oscillation does not decay quickly owing to the yaw angle. The head wave and the following wave have a continuous significant effect on the pitch; the submarine sail remains under the water surface after it submerges from the highest position. The head wave and the following wave have a slight effect on the roll and yaw before the submarine rises to the water surface; however, the roll angle suddenly increases after the submarine submerges from the highest position. As the initial angle between the submarine centerline and wave direction increases, the effect of waves on the longitudinal motion decreases. The amplitude of the pitching oscillation decreases with an increase in the initial angle between the submarine centerline and wave direction, and the waterline when the submarine oscillates on the water surface decreases. The difference in the maximum roll angle between when a submarine rises in an oblique wave and when it rises in beam sea is below 6.3∘. Submarines should try to avoid rising in a head wave and the following wave.

The application of flexible horizontal porous structure has a significant impact on the design of breakwaters and wave energy absorption devices for coastal protection and wave energy extraction, respectively. This type of structure is more economical compared to a rigid type structure. Therefore, the hydroelastic response of the flexible porous structure can be investigated to widen the influence of structural deformations in design parameters. This paper presents a generalized expansion formula for the said problem based on Green’s function in the water of finite depth (FD) and infinite depth (ID). The series form of the velocity potentials for the wave-maker problem is also derived using Green’s second identity. The derived expansion formula is applied to a real physical problem and the analytical solution is obtained utilizing a matched eigenfunction expansion method under velocity potential decompositions. The convergence study of the series solution is checked. The present results and the published experimental datasets, as well as analysis, are compared. The effect of design parameters on the hydroelastic response of the submerged flexible porous plate is analyzed. It is observed that the analysis of the results will be useful for gaining insight into how to design a wave energy absorption device.

The Bragg reflections of oblique water waves by periodic surface-piercing structures over periodic bottoms are investigated using the eigenfunction matching method (EMM). Based on the assumption of small wave amplitude, the linear wave theory is employed in the solution procedure. In the step approximation, the surface-piercing structures and the bottom profiles are sliced into shelves separated by abrupt steps. For each shelf, the solution is composed of eigenfunctions with unknown coefficients representing the wave amplitudes. Upon applying the conservations of mass and momentum, a system of linear equations is obtained and is then solved by a sparse-matrix solver. The proposed EMM is validated by several examples in the literature. Then, the method is applied to solve Bragg reflections of oblique water waves by various surface-piercing structures over periodic bottoms. From the numerical experiments, Bragg’s law of oblique waves was used to predict the occurrences of Bragg resonance.

Abstract The structures of existing coastal bridges without appropriate clearance between the still water level and low chord of the bridge deck, are vulnerable to wave-induced damage due to the strong wave force acting on the bridge deck during a hurricane or typhoon. This paper presents an analytical solution for hydrodynamic wave forces acting on girder-type bridge decks under hurricane-generated oblique water waves based on linear potential theory. First, some necessary assumptions are made, and the boundary value problem is defined. Then, the mathematical formulation and analytical solution of this wave–structure interaction problem are derived using the method of separation of variables. After determining the unknown coefficients of the velocity potentials with the matching eigenfunction expansion method, the wave forces acting on a submerged deck are obtained from the velocity field by applying the Bernoulli theorem. Finally, the analytical solution of the wave force is validated by the data from two different scaled hydrodynamic experiments. Employing the proposed method, the wave forces acting on a bridge deck are investigated considering the effect of the wave propagation direction, wave properties, and structural configuration. The parametrical analysis shows the potential for minimizing the horizontal wave force by the optimization of the structural configuration. Highlights • An analytical solution is obtained for estimating the force acting on the submerged bridge decks generated by oblique hurricane waves. • The effectiveness of the proposed approach is validated by the test data of two hydrodynamic experiments. • The effect of the wave propagation direction, wave properties, and structural configuration on wave forces are investigated. [ABSTRACT FROM AUTHOR]

ABSTRACT Park, W.S.; Won, D.H.; Seo, J.H., and Lee, B.W., 2018. Stability assessment formulas for an interlocking caisson breakwater under oblique wave conditions.. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp.1236–1240. Coconut Creek (Florida), ISSN 0749-0208. As a countermeasure for improving the stability of conventional caisson breakwaters, a method has been proposed in which adjacent caissons are interlocked with each other to consecutively resist the abnormal wave forces. It is not possible to reasonably evaluate the stability of breakwaters that have been elongated by interlocking, especially for oblique waves, by using the current design criterion defined for breakwater sections. Therefore, it was studied the stability assessment formula of an interlocking caisson breakwater under oblique wave conditions, in this study. To maintain consistency in checking the stability, it was introduced a reduction factor which is defined as the ratio of the expected maximum force for an oblique wave to that for a perpendicular wave. Using the linear wave theory, the expected maximum force was calculated considering the effect of the phase difference of hydrodynamic pressures along a breakwater. On the other hand, Goda's pressure formula was adopted as a design pressure distribution in the vertical direction to consider nonlinearities and randomness of the design wave, reasonably. Based on these assumptions, safety assessment formulas of the breakwater were developed considering the phase effect between the horizontal and uplift forces. Numerical calculations show that the proposed assessment formula for the interlocking caisson breakwater gives reasonable results, i.e., the estimated stability increases, as the wave attack angle increases. To judge the validity of the results, indirectly, the stabilities were estimated for regular and irregular wave conditions, and the results were compared each other. [ABSTRACT FROM AUTHOR]

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Nonlinear interactions of an oblique wave with an aquaculture cage array containing 16 net cages in a 2 × 8 configuration is studied in this paper. Our objective is to understand the nonlinear dynamics of the cage array induced by different hydrodynamic forcing mechanisms under oblique wave attack. To this end, we use an efficient numerical scheme with a robust implicit finite-element method for the nonlinear wave-structure interactions. The nonlinear and non-stationary data is decomposed by the empirical mode decomposition method, allowing for identification of different hydrodynamic forcing mechanisms. Then, physical model tests of a cage array in the 1 × 3 configuration under the low-frequency wave are conducted to verify the present numerical model. The harmonic responses of the surge and heave between numerical simulations and experimental tests are close to each other; indicating that the present numerical model is feasible to predict the dynamic response of the cage array in waves. The results highlight that the flexible cage with lower elastic modulus shows larger excursion in the weather side of the cage array, and the flexible cage has a better ability to absorb energy from incident waves. However, the elastic modulus of the floating collar has little effect on the surge and heave motions. Under the oblique wave attack, the nonlinear responses of a representative mooring are identified to be wave-frequency and low-frequency driven, and the nonlinear sway responses are found to be dominant by low-frequency excitations. • Nonlinear dynamics of an aquaculture cage array were examined under oblique wave attack. • Different nonlinearity components were distinguished via empirical mode decomposition. • The leading contributors for nonlinearity of mooring and motion responses were identified. • Suggestions for safety design of the fish farm were provided. [ABSTRACT FROM AUTHOR]

In this paper, a 3-D nonlinear time-domain hydroelastic analysis method for ship wave loads considering asymmetric slamming is proposed, and a 3-D Rankine panel method is used to solve the seakeeping problem. To accurately predict the hydroelastic response of the hull girder, the interaction between the hull structure and the flow field is considered in the body boundary condition. The motions and sectional loads of the ship are expressed by the superposition of the modal, which is obtained by modal analysis on a 3-D finite element model of the hull. After calculating asymmetric slamming loads using the Modified Logvinovich Model (MLM), the hydroelastic response of a 21,000-TEU container ship is analyzed, which incorporates the horizontal bending-torsional coupling vibration. Furthermore, the hull motion, slamming force, and section load are analyzed in detail to properly identify the mechanism of the slamming-whipping phenomenon. The results show that asymmetric slamming significantly affects the horizontal-torsional whipping response of the hull, especially when the wave encounter frequency matches the natural frequency. • A numerical model is presented for simulating whipping of ships under asymmetric slamming in oblique regular waves. • The structural model is coupled with a hydrodynamic solver based on the Rankine panel method. • Whipping responses of a ship is analyzed, which incorporates the horizontal bending-torsional coupling vibration. [ABSTRACT FROM AUTHOR]

A wave-balancing approach, where a ship is hydrostatically balanced on a wave with either the crest or the trough atmidship, is often used to assess the inherent strength and stability of the vessel in waves. This work examines the differences between the wave types (sinusoidal and trochoidal) as well as the values of wave length, wave height, and position of the crest along the ship, with the goal of looking for the worst-case conditions for both intact stability and longitudinal strength. A notional destroyer is used as a case study to look at the trends in strength and stability in the upright condition and at angles of heel in waves. The notional destroyer is intentionally similar to but not the same as any existing design. The study shows that looking at a wider set of wave conditions and ship states can identifymore extreme wave loading and stability degradation, suggesting that this more detailed analysis would be beneficial as a standard practice. [ABSTRACT FROM AUTHOR]