Journal of Fluids and Structures最新文献

{"title":"Exploring optimal spacing in parallel fully-passive flapping-foil hydrokinetic turbines","authors":"Siham Eddine Zantoute ,&nbsp;Leandro Duarte ,&nbsp;Guilhem Dellinger ,&nbsp;Nicolas Dellinger ,&nbsp;Mathieu Olivier ,&nbsp;Guy Dumas ,&nbsp;Abdellah Ghenaim ,&nbsp;Abdelali Terfous","doi":"10.1016/j.jfluidstructs.2025.104304","DOIUrl":"10.1016/j.jfluidstructs.2025.104304","url":null,"abstract":"<div><div>The increasing global demand for sustainable energy has led to the exploration of hydrokinetic systems, particularly flapping foil turbines, which utilize fluid–structure interactions to harvest energy from water flows. This study investigates the optimization of spacing between fully passive oscillating foils arranged in parallel configuration to maximize energy extraction efficiency. Utilizing numerical simulations with OpenFOAM’s overset mesh and URANS methods, the research examines the hydrodynamic performance and interaction effects of varying foil spacings, ranging from 3 to 15 chord lengths. For a specific configuration of a stall-flutter flapping foil turbine, results reveal that closer spacings (e.g., 3 chord lengths) can achieve comparable results to single-foil configurations, with solo efficiency <span><math><mrow><mi>η</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>299</mn></mrow></math></span> and parallel efficiency <span><math><mrow><mi>η</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>304</mn></mrow></math></span>. The study further identifies a 15% increase in mean power coefficient at a spacing of <span><math><mrow><msup><mrow><mi>d</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>=</mo><mn>5</mn></mrow></math></span>, linked to higher heave amplitude and strong fluid–structure interactions. The study highlights the potential of dual-foil setups to improve structural integrity and adaptability in diverse natural water currents. These findings offer valuable insights for the design and operation of hydrokinetic turbines, enhancing their feasibility as a sustainable energy solution.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104304"},"PeriodicalIF":3.4,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation on fluid–structure interaction in highly flexible wings","authors":"Mostafa Khazaee Kuhpar,&nbsp;Hadi Samsam-Khayani,&nbsp;Banafsheh Seyed-Aghazadeh","doi":"10.1016/j.jfluidstructs.2025.104296","DOIUrl":"10.1016/j.jfluidstructs.2025.104296","url":null,"abstract":"<div><div>This paper presents a comprehensive experimental investigation of fluid-structure interactions in a flexible, high-aspect-ratio wing during its post-critical phase, spanning a reduced velocity range of <span><math><mrow><msup><mrow><mi>U</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>=</mo><mn>1</mn><mo>.</mo><mn>47</mn><mo>−</mo><mn>35</mn><mo>.</mo><mn>34</mn></mrow></math></span> and corresponding Reynolds number range of <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>146</mn><mo>−</mo><mn>3</mn><mo>,</mo><mn>499</mn></mrow></math></span>. The angle of attack of the wing was systematically varied from 0° to 20° in increments of 2°. The structural dynamics results reveal that changes in the angle of attack significantly affect the onset of limit cycle oscillations, as well as the dominant oscillation frequencies and mode shapes. At higher flow velocities and angles of attack, a significant increase in tip deflection was observed, while minimal deflection occurred at lower or zero angles of attack. In addition to examining the structural responses, the study employs volumetric, time-resolved particle tracking velocimetry (TR-PTV) to investigate the three-dimensional (3-D) flow field around the wing and its wake. Vortex behavior and its interactions with the structural modes varied with different angles of attack and reduced velocities. Leading and trailing edge vortices adapt to wing deflection, particularly at higher angles, and the coherence of these vortical structures was shown to be influenced by the amplitude and mode shape of the wing’s oscillations.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104296"},"PeriodicalIF":3.4,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adjoint-based shape optimization using lattice Boltzmann method for flow and sound control in tandem cylinders","authors":"Kazuya Kusano,&nbsp;Hiroki Yamaguchi","doi":"10.1016/j.jfluidstructs.2025.104308","DOIUrl":"10.1016/j.jfluidstructs.2025.104308","url":null,"abstract":"<div><div>Aerodynamic noise control for flows with multiple bluff bodies is important in applications such as the pantographs of high-speed trains and landing gears of aircraft. In this study, aeroacoustic shape optimization is performed to develop an effective passive control technique for mitigating the flow-induced sound generated by a cylinder in the wake of another cylinder, focusing on two-dimensional laminar flow past two tandem cylinders at Reynolds and Mach numbers of 160 and 0.2, respectively. The shape optimization aimed at minimizing sound generation employs the lattice Boltzmann method and the unsteady adjoint method. The results highlight the benefits of diminishing the front surface curvature and adding protrusions to the side surfaces of the downstream cylinder. These changes suppress flow acceleration and negative pressure fluctuations when the stagnation point shifts owing to upstream wake oscillation, while mitigating positive pressure fluctuations through an increased flow velocity near the shifted stagnation point. Consequently, the modifications lead to a reduction in lift fluctuations and dipole sound generation, achieving a sound reduction of 2.4 dB compared to the original circular shape. However, the optimized shape significantly increases the mean drag force, indicating a trade-off in the passive control strategy.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104308"},"PeriodicalIF":3.4,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A THINC-based numerical model for incompressible flows with free surfaces on the overset grids: On preserving accuracy and conservation of volume fraction","authors":"Xin Tong ,&nbsp;Dezhu Chen ,&nbsp;Lidong Cheng ,&nbsp;Bin Xie","doi":"10.1016/j.jfluidstructs.2025.104294","DOIUrl":"10.1016/j.jfluidstructs.2025.104294","url":null,"abstract":"<div><div>In this paper, we develop an accurate and robust numerical model for incompressible multiphase flows with free surface on the unstructured overset grids within the framework of OpenFOAM. To capture the moving interface between two immiscible fluids, THINC/QQ (THINC method with quadratic surface representation and Gauss quadrature) scheme is presented on the static and dynamic overset grids using the volume of fluid (VOF) method. A novel interpolation algorithm is proposed to transfer the volume fraction across the overset grids, which significantly improves the geometric faithfulness and numerical conservation of free surfaces since the interface is reconstructed and represented as quadratic surface in the fringe cells of the overset grids using the THINC formulation. A pseudo-Laplacian approach is utilized to interpolate both the velocity and pressure fields across overset grids achieving a second-order accuracy. The incompressible Navier–Stokes equations are solved together with a transport equation of volume fraction using second-order finite volume schemes, which then is coupled with the motion solver during each time step to obtain converged solution between the hydrodynamic flow and kinematic motion of the rigid body. The so-called thincFoam/overset, when used in the transient simulation of interfacial multiphase flows, provides high-fidelity solutions with an order of magnitude reduction in the conservation error of volume fraction field. Numerical verifications have been carried out through various 2D and 3D benchmark tests, such as the water entry of a wedge, floating structure in regular waves, and water entry of a horizontal cylinder. The numerical results demonstrate that the present model shows great potential in capturing complex moving interfaces undergoing large deformations and topological changes with excellent conservation for simulating the nonlinear interaction between multiphase flows and solid structures.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104294"},"PeriodicalIF":3.4,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of corner modifications on galloping-induced response and galloping force of 3:2 rectangular section","authors":"Xiu-Yu Chen ,&nbsp;Le-Dong Zhu ,&nbsp;Qing Zhu","doi":"10.1016/j.jfluidstructs.2025.104305","DOIUrl":"10.1016/j.jfluidstructs.2025.104305","url":null,"abstract":"<div><div>Corner modifications play a significant role in influencing the galloping instability of rectangular sections, as highlighted in prior aerodynamic studies. This research focuses on the effects of various notched and chamfered corner modifications on the galloping behavior of a rectangular section with a side ratio of 3:2, offering a novel perspective by examining these modifications from an aeroelastic force standpoint. Wind tunnel experiments were conducted to simultaneously measure the galloping forces and displacements of the section under uniform flow. The results reveal that, similar to sharp-corner rectangular sections, the onset wind velocities of modified-corner sections deviate from the quasi-steady critical wind velocities for galloping and instead align with those associated with vortex-induced resonance. Among the modifications, notched corners are shown to be more effective than chamfered corners in reducing galloping amplitudes, with smaller notches significantly diminishing amplitudes and larger notches completely suppressing galloping divergence. Using a robust mathematical model for galloping forces, the underlying mechanism of the suppression effect due to corner modifications is elucidated. The superior suppression effect of notched corners, compared to chamfered corners, is attributed to their greater influence on high-order aerodynamic damping. This study extends previous findings by emphasizing the differences between sharp-corner and corner-modified rectangular sections, providing new insights into galloping mitigation strategies.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104305"},"PeriodicalIF":3.4,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scattering of oblique incident waves by a rigid floating structure in the presence of two surface-piercing thick porous breakwaters: Pattern of reflection, dissipation and wave forces","authors":"Shilpi Jain,&nbsp;Swaroop Nandan Bora","doi":"10.1016/j.jfluidstructs.2025.104285","DOIUrl":"10.1016/j.jfluidstructs.2025.104285","url":null,"abstract":"<div><div>The present work examines the wave interaction with a rigid floating structure, placed after two distinct porous structures, to mitigate wave-induced forces acting on the floating structure. The physical and mathematical consideration of the wave passing through these thick porous structures is based on the model devised by Sollitt and Cross (1972). Splitting the fluid domain into nine regions, the scattered potential in each region is obtained by setting up a system of equations using the relevant matching conditions across the boundaries. The behavior of the roots of the dispersion relation is analyzed to identify conditions under which the eigenfunction solution may become invalid. The graphs plotted for the reflection coefficient, transmission coefficient, dissipation coefficient, and wave-induced forces acting on the floating structure indicate several findings: (i) if the porosity of the second porous structure is less than that of the first porous structure, then the wave energy loss increases, thereby enhancing the safety of the floating structure through reduction of the forces, (ii) as the value of the friction factor of both breakwaters increases, the reflection coefficient decreases, (iii) by increasing the height and thickness of the breakwaters, more loss of wave energy can be achieved due to the dissipative nature of the porous structures. Consequently, the forces acting on the floating structure decrease, helping in its stability. The findings propose the appropriate values of different parameters for an efficient design of such porous breakwaters, as well as how they need to be located.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104285"},"PeriodicalIF":3.4,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visualization and measurement of shock movement during transonic limit-cycle oscillation","authors":"Eric D. Stubblefield ,&nbsp;Donald L. Kunz ,&nbsp;Nicholas W. Dona","doi":"10.1016/j.jfluidstructs.2025.104278","DOIUrl":"10.1016/j.jfluidstructs.2025.104278","url":null,"abstract":"<div><div>For more than 30 years, the phenomenon of shock-induced, trailing-edge separation has been investigated experimentally and numerically to determine whether it alone can produce a sufficiently large nonlinear force such that limit-cycle oscillation occurs in transonic flight. However, none of those research efforts have observed, much less measured the shock movement associated with shock-induced, trailing-edge separation in flight. The investigation described herein was able to both observe and measure shock movement during transonic limit-cycle oscillation in flight. The results provide conclusive evidence of the correlation between the observed shock movement and the limit-cycle oscillations, and suggest the presence of a nonlinear aerodynamic force.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104278"},"PeriodicalIF":3.4,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data assimilation for turbulence-merged channel branches with the simultaneous enhancement of hydrodynamics and aeroacoustics","authors":"Peng Wang ,&nbsp;Xu Qiang ,&nbsp;Hyung Jin Sung ,&nbsp;Yingzheng Liu","doi":"10.1016/j.jfluidstructs.2025.104283","DOIUrl":"10.1016/j.jfluidstructs.2025.104283","url":null,"abstract":"<div><div>This study explored the dynamic interplay between turbulent flow and transverse duct acoustic modes within intersecting channel branches containing two inlet branches and one outlet channel, motivated by the experimental findings of Ziada et al., 2009, entitled “Flow-acoustic coupling in T-junctions: effect of T-junction geometry” in J<em>. Press. Vessel Technol.</em> 131(4) and the work of Salt et al. 2014, entitled “Aeroacoustic sources generated by flow–sound interaction in a T-junction” in J<em>. Fluid. Struct.</em> 51, 116–131. We specifically examined how this interaction led to the simultaneous enhancement of both hydrodynamic and aeroacoustic characteristics. Compressible large eddy simulation (LES) was implemented to solve the compressible Navier–Stokes equations, and a data-assimilated momentum loss model with physical constraints was incorporated to enhance the LES accuracy and obtain the self-sustained flow–acoustic resonance fields. We further focused on the influences of upstream flow separation on the excited resonance behaviors. The numerical results with a data-assimilation strategy agreed well with the literature and acoustic modal analysis in terms of frequency, amplitude, and fundamental waveform. Three types of unsteady flow events, characterized by shear layers, recirculation zones, and separation bubbles, were identified in close response to the excited acoustic eigenmodes. The dynamics, including the acoustic-phase-resolved spatiotemporal evolution, kinematics, such as the convection trajectory and speed, and energetics, such as the aeroacoustic power sources, were further elucidated. The vertical Coriolis force, which was influenced by the secondary separation bubbles, along with the horizontal acoustic particle velocity, played a significant role in the generation of aeroacoustic power.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104283"},"PeriodicalIF":3.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation in nonlinear aerodynamic characteristics of a double-layer truss girder","authors":"Jiankun Li ,&nbsp;Cunming Ma ,&nbsp;Bo Wu ,&nbsp;Ding Zeng","doi":"10.1016/j.jfluidstructs.2025.104284","DOIUrl":"10.1016/j.jfluidstructs.2025.104284","url":null,"abstract":"<div><div>This study investigated the nonlinear aerodynamic characteristics of a double-layer truss girder at various angles of attack (AoAs) through section model wind tunnel tests. The free vibration test revealed a divergent hard flutter of the girder at 0° AoA and a self-limiting soft flutter of the girder at +3° and +5° AoAs, with responses primarily dominated by the fundamental frequency. The forced vibration test detected significant high-order harmonic components in the aerodynamic forces. Analysis of the hysteresis loops of each decomposed high-order harmonic affirmed the modification of these components on the system's energy exchange behavior over time, but refuted their impact on the occurrence of a limit cycle oscillation (LCO). Conversely, the consistency in the sign changes of the dimensionless aerodynamic work and the phase lag of the linear self-excited-moment to the torsional motion underscores the critical role of the phase difference in the occurrence of soft flutter and LCO. At last, the macroscopic energy distribution of the girder in different degrees of freedom (DOF) varies with amplitude and wind speed was quantified in terms of the three-dimensional (3D) energy map, which confirmed the consistency between the free and forced vibration tests on the section. This also revealed the fundamental mechanisms behind instability hysteresis and aerodynamic discrepancies under different DOF and AoAs.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104284"},"PeriodicalIF":3.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of a porous structure placed at the sea-bed in wave scattering around ice floes","authors":"Saniya Suhail ,&nbsp;Sunanda Saha ,&nbsp;Koushik Kanti Barman ,&nbsp;Swaroop Nandan Bora","doi":"10.1016/j.jfluidstructs.2025.104280","DOIUrl":"10.1016/j.jfluidstructs.2025.104280","url":null,"abstract":"<div><div>The present work examines the two-dimensional wave scattering problem involving a pair of ice floes of finite length separated by a finite gap over a finite ocean depth with a thick porous structure lying on an impermeable sea-bed. The physical and mathematical considerations of wave propagation through thick porous structures are analysed by analysing the interaction between the wave and the porous medium. Following linear water wave theory, the boundary value problem (BVP) is solved using the matched eigenfunction expansion method. Numerical results on various hydrodynamic coefficients are presented by varying the parameters pertaining to the porous structure and the ice floe. The reflection coefficient oscillates with an increase in the length of the first floe in the direction of the incoming waves and settles down when the length of the second floe increases. Maximum transmission is experienced when the gap between the two floes is substantial, since a higher gap allows more waves to pass through, thereby increasing the rate of transmission. The present study shows that an increase in the porosity shifts the phase of the maximum reflection, whereas a thick porous structure diminishes the maximum reflection coefficient by absorbing wave energy. With an increase in rigidity, the reflection coefficient increases, and at higher compressive force, the energy absorption increases, and consequently, the reflection reduces.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104280"},"PeriodicalIF":3.4,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}