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Establishment and validation of a versatile SPH-based numerical tank for generating wave-alone, current-alone, and wave-current-combined fields

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COASTAL ENGINEERING 2025年 197卷

作者： Lyu, Hong-Guan Sun, Peng-Nan Sun Yat Sen Univ Sch Ocean Engn & Technol Zhuhai 519000 Peoples R China Southern Marine Sci & Engn Guangdong Lab Zhuhai Zhuhai 519000 Peoples R China Guangdong Prov Key Lab Informat Technol Deep Water Zhuhai 519000 Peoples R China

Gravity wave generation, propagation, evolution, and interaction with a current playa key role in coastal and ocean engineering design. Within the Smoothed Particle Hydrodynamics (SPH) framework, this paper presents a versatile meshless numerical tank capable of generating wave-alone, current-alone, and wave-currentcombined fields. To this end, the upstream region of the numerical tank is modeled by a so-called Lagrangian particle injector that directly enforces Dirichlet source conditions to generate a desired field. Furthermore, the downstream region of the numerical tank is tackled by deploying a sponge layer in conjunction with an outflow layer to maintain flow consistency during a simulation. Finally, a series of benchmarks and applications are performed to verify and validate the accuracy, convergence, and applicability of the present numerical tank in solving marine hydrodynamics. It is demonstrated that the newly-developed numerical tank is capable of generating accurately different fields widely used in practice in an easy-to-implement manner and hence shows great potential to be a promising alternative to those traditional SPH-based numerical tanks employing a moveable paddle.

关键词： Smoothed particle hydrodynamics Numerical tank Wave-current interaction Free-surface flows fluid-structure interaction

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Ship collision model tests in a water tank

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MARINE structureS 2025年 103卷

作者： Zhu, Ling Wang, Xiangbiao Wuhan Univ Technol Sch Naval Architecture Ocean & Energy Power Engn Wuhan 430063 Peoples R China Wuhan Univ Technol Key Lab High Performance Ship Technol Minist Educ Wuhan 430063 Peoples R China

This paper investigates the dynamic responses and energy distribution in perpendicular collisions using model tests, in which the three primary elements are involved simultaneously: fluid effects, global ship motions, and local elastoplastic responses. A novel in-tank ship collision testing system has been developed to simulate perpendicular ship collisions, where the struck ship is impacted at its central section. The dynamic process of ship motions, structural deformation, energy dissipation, and added mass during collision are analyzed. Three collision scenarios are examined: Perpendicular Collision (PC), Planar Perpendicular Collision (PPC), and Central Perpendicular Collision (CPC). The calculation of energy loss during collision based on PC gives a good fit to the experimental results. It is found that the energy dissipation in the collision test is approximately linearly correlated with the initial energy input to the system. On average, about 51% of the initial kinetic energy is dissipated in the collision, mainly absorbed by the side structure through plastic deformation. These experimental data can be used for benchmarking the theoretical and numerical methods, and useful insight is provided for assessing collision scenarios.

关键词： Ship collision Perpendicular collisions Model tests Energy absorption fluid-structure interaction Elastoplastic response

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Design, aerodynamic performance and structural integrity investigations of aerofoil profiled Savonius vertical axis wind turbine

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2025年第3期47卷 1-38页

作者： Chandran, Sheeba Natarajan, Varshini Subramanian Doss, Arockia Roshan Anthony Madasamy, Senthil Kumar Arputharaj, Beena Stanislaus Rajendran, Parvathy Sourirajan, Laxana Nathan, Janani Priyadharshini Veeraperumal Senthil Raji, Arul Prakash Raja, Vijayanandh Kumaraguru Coll Technol Dept Aeronaut Engn Coimbatore 641049 Tamil Nadu India SIMATS Saveetha Sch Engn Dept Res & Innovat Chennai 602105 Tamil Nadu India Univ Sains Malaysia Sch Aerosp Engn Engn Campus Nibong Tebal 14300 Penang Malaysia

Wind energy is the suitable and sustainable sources of energy to fulfil the projected energy demands and to diminish the climate changes. Savonius vertical axis wind turbines (VAWT) are in fact the most appropriate energy producer for small-scale applications. However, the existing Savonius turbines are less efficient compared to other types of turbines. To achieve aerodynamically efficient blade design, optimal design parameters like aspect ratio, diameter, height, overlap ratio are identified. Ten different Savonius designs are modelled, and computational investigations are done using ANSYS Fluent and the outcomes are validated experimentally. The starting ability of the Savonius VAWT model is determined through static computational fluid dynamics analysis. The results revealed that conventional Bach Savonius produces 42.7% more static torque coefficient (CT) than the conventional semi-circular Savonius. The innovative two- and four-bladed, NACA 9407 imposed untwisted Savonius designs developed in this study provides 62.9% and 67.9% more static CT compared to the better-performing conventional Bach model. For material selection, the structural parameter investigations on two-bladed Bach and two-bladed NACA 9407 aerofoil imposed untwisted Savonius (hybrid model) turbine was executed based on two-way coupling fluid structural interaction (FSI) approach. From the structural analysis, it was found that the imposition of boron epoxy composite on the Bach and hybrid model provides lesser deformation, stress and strain when compared to the other materials. The hybrid model is found to be structurally efficient because it provides 96%, 35% and 37% lesser deformation, strain and stress compared to Bach model with boron epoxy composite.

关键词： Vertical axis wind turbine (VAWT) Computational fluid dynamics fluid-structure interaction Savonius VAWT Coefficient of torque

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fluid pulsation excitation characterization and pipeline vibration response analysis

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2025年 231卷

作者： Cao, Yiming Ma, Hui Guo, Xumin Chen, Weijiao Wang, Weiwei Zhao, Tianyu Lin, Junzhe Northeastern Univ Sch Mech Engn & Automat Shenyang 110819 Liaoning Peoples R China Northeastern Univ Key Lab Vibrat & Control Aeroprop Syst Minist Educ Shenyang 110819 Liaoning Peoples R China Northeastern Univ Sch Sci Shenyang 110819 Liaoning Peoples R China

Due to the influence of the hydraulic pump, the fluid medium in the pipeline is accompanied by strong periodic pressure pulsation, which is easy to induce large forced vibration in the clamppipeline system. Thus, studying the vibration characteristics of pipeline systems under fluid pulsation excitation is particularly important. The finite element method based on beam elements has distinct advantages in the modeling of spatial pipelines and complex boundaries. However, its application is often restricted due to its low computational efficiency and inaccuracy in handling fluid pulsation excitation loads. Therefore, in this paper, the measured pressure pulsation functions are taken as inputs, and the vibration response of the pipeline system under fluid pulsation excitation is solved through two-way fluid-structure interaction (FSI) analysis. The validity of the simulation is verified by comparing the results with the experimental data. On this basis, the fluid pulsation excitation forces at different nodes of the pipeline are extracted, and an in-depth analysis of the magnitude and phase distribution patterns of the excitation forces at each node is carried out. Finally, a characterization method of fluid pulsation excitation is proposed, which is based on the node excitation force fitted by two-way FSI analysis. The results indicate that the proposed fluid pulsation excitation expression can approximate the actual fluid pulsation excitation. The amplitude error between the simulation and experimental vibration responses can be controlled within an acceptable range. Specifically, the error under a pressure of 8 MPa is controlled within 20 %, which verifies the effectiveness of the proposed characterization method.

关键词： Pipeline system Finite element method fluid pressure pulsation fluid-structure interaction

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High-feasibility parafoil dynamic formation real-time adaptive trajectory planning based on ABC-MASAC in complex environments

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NEUROCOMPUTING 2025年 638卷

作者： Yu, Jiaming Sun, Hao Sun, Qinglin Zhu, Hong Sun, Mingwei Jin, Zhengxiang Chen, Zengqiang Nankai Univ Coll Artificial Intelligence Tianjin 300350 Peoples R China Jimei Univ Coll Nav Xiamen 361021 Fujian Peoples R China

In large-scale parafoil formation airdrop missions, unpowered parafoils face challenges in precise speed control and are highly susceptible to wind disturbances. Traditional fixed formation trajectories require precise speed control and cannot adapt in real-time to environmental changes. Furthermore, dynamic models based on rigid-body assumptions fail to accurately reflect the aerodynamic characteristics of actual systems, resulting in poor trajectory feasibility. To address the aforementioned issues, this paper proposes a high-feasibility, real-time adaptive trajectory planning method for parafoil airdrop dynamic formations. First, a high-precision flexible eight-degree-of-freedom (8-DOF) dynamic model is developed using fluid-structure interaction (FSI) techniques, which can simulate the real aerodynamic deformation and dynamic response of the parafoil, ensuring the planned trajectories are more consistent the behavior of actual systems. Additionally, an Adaptive Behavior Cloning Multi-Agent Soft Actor-Critic (ABC-MASAC) algorithm is proposed, which accelerates training by adaptively adjusting the follower policy, thereby improving the training efficiency of the trajectory planning model. Detailed simulation results demonstrate that the proposed parafoil airdrop formation trajectory planning method achieves high trajectory feasibility and real-time planning capability, while significantly accelerating training speed.

关键词： Parafoil formation Trajectory planning Soft actor-critic fluid-structure interaction Dynamic constraints

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A 1D model for the dynamic instability of magnetized beams in leakage flow energy harvesters

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2024年 209卷

作者： Castanon, Facundo Saravia, C. Martin Machado, Sebastian P. Espeche, Julian C. Univ Tecnol Nacl Fac Reg Bahia Blanca Grp Invest Multifis Aplicada CONICET 11 Abril 461 Bahia Blanca Argentina

This paper presents a one-dimensional fluid-structure interaction model for investigating the dynamic stability of elastic mounted beams under the influence of magnetic forces in a leakage flow energy harvesting environment. The interaction between the beam and external magnetic fields is represented by a nonlinear long range force distribution that is non linearly dependent on the beam displacement. The formulation results in a two way coupled fluid-structure interaction system that is one way coupled with the electromagnetic system. A perturbation technique is utilized to linearize the second order equilibrium equations of the coupled system, which are then transformed into a set of first -order ordinary differential equations in the state space. The effect of the linearized magnetic force coefficient on the eigenvalues and dynamic stability of the system is analyzed through a parametric study. The results indicate the onset of oscillatory dynamics in the coupled magneto -fluid -structural system is a non monotonic function of the magnetic force.

关键词： Energy harvesting Leakage flow fluid-structure interaction Flutter Nonlinear dynamics

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Nonlinear Vibrations and Stability Analysis of GPL Reinforced Pipes Conveying fluid Excited by Arbitrary Initial Conditions: An Optimized Analytical Solution

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INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS 2024年第19期24卷 2450210-2450210页

作者： Sabahi, Mohammad Ali Saidi, Ali Reza Bahaadini, Reza Shahid Bahonar Univ Kerman Dept Mech Engn Kerman Iran Gol Gohar Iron & Steel Dev Co GISD Co Sirjan Iran

In this study, nonlinear vibrations and stability of multilayer functionally graded (FG) pipes conveying fluid laying on nonlinear elastic foundation and reinforced by graphene nanoplatelets (GPLs) are investigated with an emphasis on optimized analytical method. Various types of GPL distribution patterns are considered and to estimate the mechanical characteristics of the reinforced pipe the Halpin-Tsai micromechanics theory is applied. The nonlinear differential equation of motion is obtained by using Von-Karman strain relations in conjunction with the Euler-Bernoulli beam theory and applying Hamilton's principle. The Galerkin technique has been used for discretizing the partial differential equation. The optimized homotopy analysis method (HAM), as a strong analytical method, is utilized to solve the nonlinear differential equation by considering different initial excitations. The convergence-control parameter is taken into account to guarantee the convergence of the analytical solution. In this study, an exact solution based on HAM for the critical flow velocity and nth nonlinear frequency is presented. Additionally, series solutions for the nonlinear time responses of the transverse and longitudinal vibrations of fluid-conveying pipe based on optimized HAM are obtained for the first time. In the numerical results, the effects of arbitrary initial conditions and different physical characteristics on the nonlinear frequencies and time responses are extensively examined. It is shown that the nonlinear frequencies and critical flow velocity of the pipe depend not only on the initial excitation amplitude, but also on the entire initial excitation function applied on the pipe.

关键词： fluid-structure interaction stability analysis nonlinear vibration nanocomposite pipe arbitrary initial excitations optimized analytical solution

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A Time Domain Model to Predict Dynamic Response of Multiple Floating Bodies Connected With Hinges Based on the Kane Method

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JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME 2024年第3期146卷 031701-031701页

作者： Liu, Junyi Chen, Xujun Ji, Song Huang, Heng Chen, Xi Tu, Qunzhang Army Engn Univ PLA Coll Field Engn Nanjing 210007 Peoples R China

A two-dimensional model to estimate the hydrodynamic response of hinged multiple floating body systems in the time domain is established based on the Kane method. The reduced Kane equations applicable to the dynamic response of multi-floating body system with hinges are first deduced. The issue of hinge constraint in the system is addressed by defining the corresponding generalized speeds as zeros, while the wave actions are considered based on the potential flow theory. Then the corresponding calculation program is developed prior to undertaking the model test. Verification of the Kane-based model and the veracity of the program developed is performed through a series of contrastive analyses on a hinged floating bridge in various cases including regular waves, moving loads, and their combinations. The predictions obtained by the proposed model show satisfactory agreements with the model test measurements. The related results indicate that the motion responses of the first pontoon are greatest in a hinged floating bridge, and its motion amplitudes descend nonlinearly with the increment of wave frequency. The time-history motion responses of hinged multi-floating bodies in the middle present saddle shapes with some fluctuations as a whole under the combined effect of wave and moving loads. The Kane-based model is convenient to analyze the dynamic characteristics of a hinged multi-floating body system in regular waves, and it could be further extended to consider the effects of irregular waves, inhomogeneous sea conditions, as well as the nonlinear connections on the system.

关键词： ocean engineering hinged multi-floating bodies multibody dynamics Kane method time-domain analysis dynamics of structures fluid-structure interaction hydrodynamics ocean space utilization structural safety and risk analysis

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Asynchronous parallel reinforcement learning for optimizing propulsive performance in fin ray control

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ENGINEERING WITH COMPUTERS 2024年 1-18页

作者： Liu, Xin-Yang Bodaghi, Dariush Xue, Qian Zheng, Xudong Wang, Jian-Xun Univ Notre Dame Dept Aerosp & Mech Engn Notre Dame IN 46556 USA Univ Maine Dept Mech Engn Orono ME 04469 USA Rochester Inst Technol Dept Mech Engn Rochester NY 14623 USA Cornell Univ Sibley Sch Mech & Aerosp Engn Ithaca NY 14853 USA

Fish fin rays constitute a sophisticated control system for ray-finned fish, facilitating versatile locomotion within complex fluid environments. Despite extensive research on the kinematics and hydrodynamics of fish locomotion, the intricate control strategies in fin-ray actuation remain largely unexplored. While deep reinforcement learning (DRL) has demonstrated potential in managing complex nonlinear dynamics;its trial-and-error nature limits its application to problems involving computationally demanding environmental interactions. This study introduces a cutting-edge off-policy DRL algorithm, interacting with a fluid-structure interaction (FSI) environment to acquire intricate fin-ray control strategies tailored for various propulsive performance objectives. To enhance training efficiency and enable scalable parallelism, an innovative asynchronous parallel training (APT) strategy is proposed, which fully decouples FSI environment interactions and policy/value network optimization. The results demonstrated the success of the proposed method in discovering optimal complex policies for fin-ray actuation control, resulting in a superior propulsive performance compared to the optimal sinusoidal actuation function identified through a parametric grid search. The merit and effectiveness of the APT approach are also showcased through comprehensive comparison with conventional DRL training strategies in numerical experiments of controlling nonlinear dynamics.

关键词： Off-policy RL Dynamic control Computational fluid dynamics fluid-structure interaction

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Hydrodynamic effects and prediction of the responses of underwater rectangular bridge piers during earthquakes

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ENGINEERING structureS 2025年 326卷

作者： Chen, Yu Huang, Xin Wu, Kun Li, Zhong-Xian Civil Aviat Univ China Sch Transportat Sci & Engn Tianjin 300300 Peoples R China Tianjin Univ Key Lab Coast Civil Struct Safety Minist Educ Tianjin 300350 Peoples R China

The hydrodynamic effect on underwater bridge piers during seismic action not only enhances pier responses but also poses a threat to bridge safety. Reliable and straightforward prediction of these hydrodynamic effects is crucial for engineers engaged in seismic analysis and bridge design. To address this need, this study introduced a numerical simulation approach for fluid-structure interactions during earthquakes that was validated through an underwater shaking table test on a bridge pier. Five artificial seismic waves were subsequently generated based on the target response spectra for diverse site conditions. A series of numerical simulations were conducted on rectangular piers subjected to unidirectional seismic action, with the seismic force oriented perpendicular to the longer side of the cross-section. The simulations were performed for various values of the height-to-width ratio (HWR), water depth-to-pier height ratio (DHR), and section aspect ratio (SAR) of the piers and for various values of the additional upper mass-to-pier mass ratio (MMR). By analysing the increasing ratio (IR) of pier behaviour due to hydrodynamic effects, a prediction model for the hydrodynamic effect on rectangular bridge piers was established. These findings reveal that increasing the water depth amplifies the seismic response of bridge piers, with a more pronounced hydrodynamic effect observed as the HWR of the bridge pier increases. Augmenting SAR enhances the seismic response of bridge piers, particularly for larger HWRs. Furthermore, increasing the additional mass atop the pier intensifies the seismic response while concurrently masking the influence of hydrodynamic effects. Notably, for taller piers, a greater horizontal inertia force due to the additional upper mass significantly masks the hydrodynamic effect. Finally, comparison between the IR values obtained from numerical simulations and those generated by the prediction model reveals a discrepancy within 6%, validating the

关键词： fluid-structure interaction Bridge pier Hydrodynamic effect Prediction model Earthquake Numerical simulation

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