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The study of fluid–structure interactions in elastic structures is highly important in hydraulic structural engineering. This paper adopts the smooth particle hydrodynamics (SPH) coupling method to simulate dam failure water impact elastic plate flow and solid coupling problems. In addition, a numerical simulation is performed on the study of the free surface flow impact of the elastic plate structure on the main dynamic characteristics, including the impact force distribution and the change process. Additionally, the elastic structure of the vibration amplitude and frequency change rule, as well as the drastic changes in free surface flow, are also carried out. In this paper, the synchronous finite element algorithm is used to analyze the problem to obtain FEM results Additionally, two-dimensional benchmark physical tests are designed for dam-break water flow impacting an elastic plate are conducted, focusing on a comparative analysis of the numerical results of the SPH method with the results of physical tests and verifying the validity, accuracy, and superiority of the SPH coupling method for solving the problem of fluid‒solid coupling in elastic structures. On this basis, to explore the relevant physical quantities that cannot be measured or described during the test process, the flow–solid coupling characteristics of the elastic plate impacted by water flow are further understood by analyzing the nature of the flow field, the change in the flow–solid force of the elastic plate and the change rule of the frequency spectrum. The results show the following: (i) The jumps in velocity between the streams and the strong curvature of the free liquid surface lead to the creation of vortices at the cavities. (ii) The flow solid force under the impact of water flow increases and then decreases, and the smaller the deformation of the elastic structure is, the greater the force is. (iii) The vibration frequency of the fixed end of the elastic structure gradually decreases along the free end frequency, and the larger the deformation of the free end of the elastic plate is, the weaker its vibration response is. In addition, the natural frequency of the elastic plate under water flow impact is slightly lower than that under free vibration of the elastic plate. The related research results provide reference and guidance for the fluid–structure interaction problem. • Physical tests of elastic plates impacted by dam break water flow are studied. • Dynamic characteristics of elastic structures based on the SPH solver are analyzed. • The generation of vorticity, fluid-solid forces, and spectral changes are analyzed. • The water flow impacting the elastic plate based on SPH and FEM solver is studied. [ABSTRACT FROM AUTHOR]

Monopiles are important structures in offshore wind engineering, primarily serving as foundations for wind turbines. When installed on a sandy seabed, local scour around monopiles can reduce their capacity, and is a significant hazard to be addressed in the design process. This paper provides a review of research related to local scour around monopiles, focusing on the following aspects: (1) identifying flow structures related to local scour, (2) synthesizing existing data on equilibrium scour depth and scour time-scale, (3) summarizing technology for observing local scour through laboratory experiments, numerical simulations and field observations, and (4) outlining the existing challenges and research opportunities. • This work reviews local scour around monopiles, covering flow processes, engineering assessment and scour observations. • The equilibrium scour depth and time scale around monopiles under various flow conditions has been summarized. • A discussion about filed observation of monopile scour is presented. • Knowledge gaps and research opportunities have been identified and listed in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of the pulse width and amplitude on the scouring of sand beds by vertical submerged pulsed jets using a combination of experimental and numerical calculations. The reliability of the numerical calculations is verified through a comparison between the numerical simulations with the sedimentation scour model and the experimental data at a low pulse width T 2 of 0, with the result that the various errors are within 5%. The results show that the scour hole depth | h min | grows with the relative low pulse width T 3 throughout three intervals: a slowly increasing zone I, a rapidly increasing zone II, and a decreasing zone III, producing a unique extreme value of | h min |. The optimal scouring effect equation was obtained by analytically fitting the relationship curve between the pulse amplitude V and the relatively low pulse width T 3. Including the optimal T 3 and optimal duty cycle ƞ. The difference in the scour hole depth | h min | under different pulse amplitudes is reflected in the initial period F of the jet. With an increasing pulse amplitude, | h min | goes through three intervals: an increasing zone M, decreasing zone N, and rebound zone R. It is found that the scouring effect in the pulse jet is not necessarily always stronger with a larger amplitude. The results of the research in this paper can provide guidance for optimizing low-frequency pulsed jets for related engineering practices, such as dredging and rock-breaking projects. • Numerical simulations and experiments were combined to investigate pulsed jet scour. • The effect mechanism of pulse amplitude on the variation of scour hole depth was analyzed. • Models for the prediction of relative low pulse width with the inlet pulse amplitude have been developed. [ABSTRACT FROM AUTHOR]

Maneuverability is a critical aspect of ship navigation performance, particularly during polar navigation, where the presence of ice significantly affects maneuverability compared to open water navigation. By coupling the non-smooth discrete element method (NDEM) with the Maneuvering Modeling Group (MMG) model, this paper proposes a numerical model to simulate the maneuvering motion of full-scale ships in broken ice regions. In the proposed model, the ship-ice interaction was solved through NDEM, while the 3-DOF MMG model was utilized to simulate the autonomous navigation movement of ships. Based on the relationship between ship turning radius and ship speed, the critical relationship between ice moment and ice resistance is derived in this paper, which can be used to verify the rationality of simulation results of maneuvering motion. In addition, the effects of ice concentration, size, thickness, and ship speed and rudder angle on the ship's maneuvering trajectory and steering flexibility are analyzed by simulating turning motion and Zig-Zag maneuvers. This provides an effective numerical model to simulate the maneuvering motion of a ship in a broken ice area with low-medium ice concentration. • A NDEM-MMG numerical coupled model is proposed to effectively simulate maneuvering motions of ships in broken ice areas. • The ice moment and resistance critical relation is derived to judge the change of ship's turning range in broken ice areas. • By simulating the turning and Zig-Zag motions, the effects of ice floes on ship's maneuvering performance have been analyzed. [ABSTRACT FROM AUTHOR]

The effect of landslide-generated tsunami waves on coastal areas can be initially understood through a numerical simulation. Moreover, an efficient numerical simulation would be beneficial for predicting tsunami waves. However, a single numerical model that can capture the landslide and wave propagation is still impractical, especially in a large-scale domain. A domain-partitioning technique or coupling model would be more practical. This paper reports a numerical study of a landslide-generated wave, which uses a multi-phase CFD model for the landslide phenomena and a surface wave model based on Boussinesq-type equations for wave propagation. The proposed coupling model that sits between the multi-phase CFD and wave models validated by laboratory experiments is shown to be effective. The computation domain of the CFD model can be defined as small as it covers the impacted area of the landslide. The rest of the domain can be handled by the wave model that propagates the wave accurately with a low computation cost. • A coupling model between multi-phase flow and Boussinesq-type models is presented. • The coupling simulates the subaerial landslide-generated wave on a laboratory scale. • The proposed coupling model agrees reasonably well with the laboratory experiments. • The numerical simulation domain of the two models is partitioned efficiently. [ABSTRACT FROM AUTHOR]

This paper reports an innovative suction caisson with a bio-inspired surface of the snakeskin, which is named as the scaled suction caisson (SSC). The bio-inspired surface of the snakeskin has an anisotropic mechanical behavior. The interface friction decreases as the bio-inspired surface moves forward, but increases as the bio-inspired surface moves backward. Therefore, the SSC has the advantages of decreasing the penetration resistance and increasing the pull-out capacity. The numerical simulations are conducted to investigate the inclined bearing behaviors of the SSC. This study shows the inclined bearing capacity of the SSC is larger than that of the traditional suction caisson (TSC). For example, when the loading angle θ = 30°, the inclined bearing capacity of the SSC with an aspect ratio of bio-inspired surface L 1 / D 1 = 32 (L 1 and D 1 are the height and diameter of the bio-inspired surface, respectively) at different padeye depths averagely increases by 10.2 % compared with the TSC. In the V - H plane, the yield envelope area of the SSC gradually expands and reaches stability as the L 1 / D 1 decreases from 66 to 32. A calculation method is proposed to predict the V - H yield envelope. Furthermore, the design framework is established considering the requirement of the inclined bearing capacity and buckling. • The inclined bearing capacity and failure mode of the SSC are investigated. • The V - H yield envelopes of the SSC under different padeye depths are obtained. (3) A calculation method for establishing the V - H yield envelopes of the SSC is proposed. • A design framework of the SSC is proposed. [ABSTRACT FROM AUTHOR]

The subsea capping stack is crucial equipment for emergency rescue in a blowout scenario, which determines the success or failure of the emergency rescue. The secondary risk prevention of the blowout emergency continues to face a persistent challenge. This paper proposes a methodology framework for emergency risk of the subsea capping stack, which aims to realize the quantitative risk assessment of installation operation by integrating numerical simulation and an Artificial neural network (ANN) model. Herein, the numerical model of fluid impact for the capping stack is constructed, and the impact forces of the blowout fluid are analyzed. The calculation results indicate that the blowout pressure, water depth, and installation height significantly affect the impact force during emergency operations. Furthermore, a genetic algorithm optimizing the neural network (GA-BP) model for quickly predicting the blowout impact force is established to improve emergency response efficiency based on sufficient simulation data. The prediction model has a minor mean absolute percentage error (MAPE), and its accuracy is also verified compared with the SVM model. Besides, the developed model speeds up the processing time from hours to seconds compared to numerical simulation. Therefore, it can provide a decision-making basis for emergency engineers at the site of blowout accidents more efficiently. • An integrated methodology is proposed to quantify the installation risk for the subsea capping stack. • The simulation model of the capping stack during the installation process is constructed to predict the impact forces. • A prediction model is developed to speed up the processing time from hours to seconds compared to numerical simulation. [ABSTRACT FROM AUTHOR]

As aquaculture structures continue to grow in size and keep being moved to increasingly more exposed locations, extensive engineering work is required to design safe and cost-efficient structures. This paper presents a simplified analytical model to estimate the forces acting in the vertical ropes supporting the aqua culture net. The complex non-linear three-dimensional (3D) problem is simplified into 2D using a matrix method. The basis for the method is a quasi-static solution calculated using the principle of virtual displacements. Results from the simplified method are compared to numerical simulations performed using SIMA. The simplified method provides results with good accuracy and is therefore well-suited for the preliminary design of fish net ropes given the low computation time compared to other available methods. • A simplified method estimating the forces in the ropes supporting the aquaculture net under the action of regular waves and current is proposed. • Simple matrix method based on the principle of virtual displacements. • Provides quick and accurate estimates without the need for time domain simulations. • Useful in a design phase and in marine operations. [ABSTRACT FROM AUTHOR]

A wave energy converter (WEC) must be controlled to adapt to changing wave conditions to improve its conversion efficiency. Radiation hydrodynamic parameters are essential for the resonance control of the WEC. Although existing numerical simulation and flume test methods can provide these parameters, the results obtained are often significantly different from the actual situation and do not meet the requirements for WEC control. To address this problem, an in-situ testing method for radiation hydrodynamic parameters is proposed. By this method, the analytical expression of WEC's radiation hydrodynamic parameters concerning frequency can be obtained based on a single free decay response curve. Additionally, methods for eliminating the effects of wave disturbances and mechanical friction are also presented in this paper. Based on a resonant device C-WEC, the proposed methods have been verified by numerical simulations and flume tests, providing a fundamental technology for controlling WEC to achieve resonance. • In-situ testing method of wave energy converter's radiation parameter is proposed. • A mechanical friction effect correction method is proposed. • A wave disturbance weakening method is proposed. • The proposed method is verified by numerical simulations and experimental tests. [ABSTRACT FROM AUTHOR]

In order to meet the application requirements of the underwater parachute, the underwater inflation performance of a drag parachute is investigated based on numerical simulation and water tank test. A method for simulating the inflation process of underwater parachute based on Arbitrary Lagrangian Eulerian (ALE) method is proposed. The variation of axial force in the numerical simulation exhibits a similar trend to that observed in the model test, and the discrepancy of value between them is relatively insignificant. The purpose of this paper is to provide a basis for the evaluation and design of underwater parachutes for underwater applications. The effects of parameters such as permeability and flow velocity on the inflation performance are discussed in detail, and the analysis is carried out for parameters such as axial force and structural deformation. The results show that the high-stress zone and high-pressure intensity zone of the underwater parachute were found to be mainly concentrated in the center of the canopy and the joint. It can be observed both in model test and numerical simulation that, during the inflation process, vortexes are generated inside and outside the canopy. After the inflation shape of the canopy has stabilized under steady flow, lateral forces are generated on the parachute due to asymmetric vortex shedding, which cause the parachute to rotate around the axis. • A method for simulating the inflation process of underwater parachute based on ALE is proposed. • Vortex motion and breathing phenomena can be observed both in the model test and simulation. • Effects of flow velocity and permeability on the canopy stress and flow field velocity distribution are obtained. [ABSTRACT FROM AUTHOR]

In this paper, the full boundary layer flow on a C-series marine propeller is investigated through Under-resolved Direct Numerical Simulation (U-DNS). The simulated Reynolds number of 600,000 corresponds to experimental conditions for which a lab-scale propeller was designed and tested at MARIN's towing tank in the late 1970s. The operating conditions of the simulations are set by matching the experimental advance ratio of 0.73. The simulation uses the high-order spectral element code Nek5000 to solve the boundary layer flow accurately. A specific computational domain is set to simulate the flow in the near-wall region of one of the propeller blades. The results are validated using experimental data on the propeller's performances and the boundary layer regimes obtained from previous paint test measurements. The detailed boundary layer flow analysis provides new insights into understanding the transition mechanisms on both sides of the blade. Results suggest that centrifugal instabilities occur at the blade's surface, inducing laminar-to-turbulent transition. A new flow map of the boundary layer regime is then discussed. The laminar cross-flow vortice inception and breakdown are studied in detail to characterize the transition dynamics. • DNS of a complete boundary layer transition around a marine propeller blade. • The boundary layer flow at the suction side is close to experimental observations. • The pressure side experiences transition through centrifugal instabilities. • Experiments predict early transition due to streak inception raising wall friction. [ABSTRACT FROM AUTHOR]