Journal of Fluids and Structures最新文献

{"title":"Aerodynamic and acoustic analysis of a self-excited oscillation cylinder in a low Mach flow using a hybrid method","authors":"Kai Wang,&nbsp;Guoyong Jin,&nbsp;Tiangui Ye,&nbsp;Yukun Chen,&nbsp;kaiyao Song","doi":"10.1016/j.jfluidstructs.2025.104339","DOIUrl":"10.1016/j.jfluidstructs.2025.104339","url":null,"abstract":"<div><div>A cylinder placed in low Reynolds number flows can cause instabilities, such as unstable fluid induced forces and non-periodic vibrations of structures, leading to increased fatigue loading. It can also generate significant flow-induced noise. Therefore, understanding the vibrational behavior and its acoustic propagation mechanism in this configuration is crucial. This study investigates the aerodynamics and acoustic characteristics of a transversely self-excited oscillating circular cylinder at <em>Ma</em> = 0.2, <em>Re</em> = 150 and <em>m</em>* = 5. To simplify the problem, we model the movement of the cylinder using a mass-spring-damper system and solve the motion trajectory using the Newmark-<em>β</em> method. The acoustic governing equations formulated within viscous/acoustic splitting method in terms of a moving mesh are derived and validated by comparison with the direct numerical simulation method results. Key parameters, including amplitude ratio, frequency ratio, lift and drag coefficients, and phase angle between lift and displacement were analyzed over a range from reduced velocity <em>U_r</em> = 2 to <em>U_r</em> = 9. Various vortex-induced vibration phenomena, such as \"lock-in,\" \"phase switching,\" and \"beating,\" are observed. The predicted sound signal exhibits distinct variations across the initial, lower and desynchronization branches:minimal impact of vibration on the acoustic field in the initial branch, a \"beating\" phenomenon between the initial and lower branches, the acoustic field rotation due to a sudden increase in drag force in the lower branch, and reduced acoustic wave intensity in the desynchronization branch due to vortex shedding suppression.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104339"},"PeriodicalIF":3.4,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084030","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":"Scaling laws and performance enhancement mechanism of compact tandem flapping foils","authors":"Xingjian Lin ,&nbsp;Penghui Zhu ,&nbsp;Yusheng Liu ,&nbsp;Jie Wu","doi":"10.1016/j.jfluidstructs.2025.104334","DOIUrl":"10.1016/j.jfluidstructs.2025.104334","url":null,"abstract":"<div><div>The tandem dual-wings/fins of natural flyers/swimmers exhibit superior propulsive performance. However, the fluid mechanism behind it remains uncertain. In this paper, the self-propulsion of compact tandem flapping foils with a fixed gap is numerically studied. It is found that as compared with a single foil, the compact tandem-foil system has significant speed enhancement and efficiency augmentation. When the phase difference and gap distance are appropriate, the maximum increase in speed can reach up to 54 %, and increase in efficiency can reach up to 72 %. Subsequently, some simple scaling laws are proposed for the propulsive speed and power consumption of the compact tandem-foil system. Furthermore, the fluid-structure interactions between the two foils are analyzed, and it is found that the speed enhancement primarily results from the thrust increase of the hind foil. The results obtained here may shed some light on understanding the propulsion mechanisms of the dual-wings/fins of natural flyers/swimmers.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104334"},"PeriodicalIF":3.4,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941520","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":"Flow-induced vibrations of various bluff bodies: a review of blockage and wall effects","authors":"Md. Mahbub Alam","doi":"10.1016/j.jfluidstructs.2025.104328","DOIUrl":"10.1016/j.jfluidstructs.2025.104328","url":null,"abstract":"<div><div>Bluff bodies subjected to fluid flow are unconfined or confined by two parallel walls or by one wall in many engineering applications and nature. They may undergo vortex-induced vibration (VIV) and/or galloping depending on the body shape and the confinement degree. This paper presents a review of flow-induced vibrations of confined bluff bodies of different cross-sections, including circular, square, rounded-corner, and rectangular. Synthesized are the effects of the flow confinement by two walls (two-wall–cylinder interactions) or one wall (one-wall–cylinder interactions) on vibration response, frequency response, lock-in, aerodynamic force, vortex shedding, motion trajectory, phase lag, VIV width, hysteresis in VIV, and galloping at different ranges of mass ratio, damping ratio, and Reynolds number. For a circular cylinder, an increase in blockage ratio reduces the maximum vibration amplitude, causes a shrink in the VIV width and a shift in the VIV regime to smaller reduced velocities, and introduces hysteresis between initial and lower branches. For a square cylinder, the effect of blockage ratio on vibration amplitude is not straightforward but depends on the cylinder mass ratio. A higher blockage ratio suppresses galloping for a square cylinder. The research gap in the literature is pinpointed and put forward for future investigations.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104328"},"PeriodicalIF":3.4,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143935911","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":"Role of fluid-structure interactions in mechanosensation during hovering flapping flight","authors":"Menglong Lei,&nbsp;Chengyu Li","doi":"10.1016/j.jfluidstructs.2025.104329","DOIUrl":"10.1016/j.jfluidstructs.2025.104329","url":null,"abstract":"<div><div>Insect wings, known for their intricate structure and function, inherently deform during flapping motion. These deformations can be classified into chordwise cambering, spanwise bending, and root-to-tip twisting, arising from non-uniform venation distribution, aerodynamic loading, and wing inertia. Crucially, such deformations play a vital role in enhancing both aerodynamic performance and mechanosensory function. To investigate the complex interplay between wing structure, unsteady aerodynamics, and mechanosensation, we developed a fully coupled three-dimensional fluid-structure interaction (FSI) solver. This framework integrates an in-house Navier-Stokes equations solver for resolving the flow field with the open-source Vega FEM code to solve the solid structure dynamics. Our FSI simulations reveal that venation structures significantly enhance aerodynamic efficiency by enabling complex deformation patterns. Wings with moderate stiffness (reduced stiffness <em>K</em> = 3.94) values strike an optimal balance between lift generation and energy efficiency, outperforming both rigid and excessively flexible configurations (6 % higher lift generation and 89 % higher power efficiency, compared to rigid wings). In contrast with uniform wings, at <em>K</em> = 3.94, wings with venation structure generate 8 % less lift but the power efficiency is 25 % higher. Additionally, the time history of strain energy density closely mirrors the trend of aerodynamic forces, suggesting that local strain energy sensed by embedded mechanosensors could potentially predict aerodynamic forces. This finding highlights a direct functional link between unsteady aerodynamics and sensory feedback in insect wings. These results underscore the critical roles of wing stiffness, venation structures, and unsteady aerodynamics in shaping both the aerodynamic and sensory performance of insect-inspired wings. By elucidating how insects derive aerodynamic and sensory benefits from wing flexibility, this study provides valuable insights into insect flight mechanisms and offers inspiration for the design of efficient and adaptive flapping-wing Micro Air Vehicles.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104329"},"PeriodicalIF":3.4,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143899890","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":"Steady-state nonlinear dynamics of a flexible beam with large deformation under oscillatory flow","authors":"Jingkun Gao ,&nbsp;Weidong Zhu ,&nbsp;Yaqing Jin ,&nbsp;Pengyao Gong","doi":"10.1016/j.jfluidstructs.2025.104327","DOIUrl":"10.1016/j.jfluidstructs.2025.104327","url":null,"abstract":"<div><div>This work investigates the steady-state nonlinear dynamics of a large-deformation flexible beam model under oscillatory flow. A flexible beam dynamics model combined with hydrodynamic loading is employed using large deformation beam theory. The equations of motion discretised using the high-order finite element method (FEM) are solved in the time domain using the efficient Galerkin averaging-incremental harmonic balance (EGA-IHB) method. The arc-length continuation method and Hsu’s method trace stable and unstable solutions. The numerical results are in accordance with the physical experimental results and reveal multiple resonance phenomena. Low-order resonances exhibit hardening due to geometric nonlinearity, while higher-order resonances transition from softening to hardening influenced by inertia and geometric nonlinearity. A strong coupling between tensile and bending deformation is observed. The axial deformation is dominated by inertia, while bending resonance is influenced by an interplay between inertia, structure stiffness, and fluid drag. Finally, the effects of two dimensionless parameters, Keulegan and Carpenter number (<em>KC</em>) and Cauchy number (<em>Ca</em>), on the response of the flexible beam are discussed.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104327"},"PeriodicalIF":3.4,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895506","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 incidence angle on the wake of a wall mounted slotted cylinder in an open channel flow","authors":"John A. Boamah ,&nbsp;A.-M. Shinneeb ,&nbsp;R. Balachandar","doi":"10.1016/j.jfluidstructs.2025.104325","DOIUrl":"10.1016/j.jfluidstructs.2025.104325","url":null,"abstract":"<div><div>This experimental study investigates the wake flow generated by a vertically, wall-mounted slotted-cylinder in shallow channel flow. The slot, uniformly cut along the central plane of the cylinder, has a thickness equal to 0.1 times the cylinder diameter. The primary parameter examined is the incidence angle <em>θ</em> between the slot axis and the main flow direction, selected by rotating the slotted-cylinder clockwise to four different positions. The study aims to understand the impact of <em>θ</em> on the wake flow characteristics by investigating both the instantaneous and mean velocity fields, as well as the coherent structures. The Reynolds number, based on the water depth, is approximately 25,000. Particle image velocimetry (PIV) measurements were conducted along the vertical mid-plane and on three horizontal planes.</div><div>The results revealed the formation of three-dimensional (3D) mean recirculation zones in the wake of the cylinder without a slot, resembling a counter-rotating U-shaped vortical structure. For θ ≥ 60°, this 3D shape persists, while for θ &lt; 60°, it varies by the angle. The jet emanating from the slot suppresses velocity fluctuations when injected into the wake region at incidence angles θ &lt; 60° In contrast, at θ ≥ 60°, there is a transition to a stimulating effect that enhances turbulent kinetic energy (TKE) production. Proper orthogonal decomposition (POD) results highlight differences in kinetic energy transfer to the turbulent flow across various cases of the slotted-cylinder. Moreover, the slot flow exhibits both blowing and suction effects, with varying intensity and dominance throughout the shallow water layer.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104325"},"PeriodicalIF":3.4,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874783","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":"Synthesis and characterisation of turbulent flows to predict fatigue loading of tidal turbines in arrays","authors":"Hannah Mullings,&nbsp;Pablo Ouro,&nbsp;Tim Stallard","doi":"10.1016/j.jfluidstructs.2025.104321","DOIUrl":"10.1016/j.jfluidstructs.2025.104321","url":null,"abstract":"<div><div>The onset flows used for tidal turbine design are, at present, based on simplifications of the naturally occurring tidal flow, and design standards consider in-wake loading based on an effective turbulence parameter. This work uses a quasi-steady blade element momentum model to assess alternative unsteady onset flow characterisation methods for prediction of the fatigue loading of turbines, when operating in the complex onset flows that occur in an array. Fatigue loads are evaluated for each turbine within a two-row array using onset turbulent flow from both a large eddy simulation and synthesised by superposition of shear, an empirical wake model and a spectral turbulence model. This is shown to provide blade damage equivalent loads within 1% for a turbine operating in the highest transverse shear region when compared to the direct use of the Large Eddy Simulation (LES) flow fields. Fatigue loads vary with turbulence and onset shear. Approaches for characterising such flows and resultant loads are evaluated including based on effective turbulence and on the signal to noise ratio (SNR) of the relative velocity to the blade at a radial position close to the centroid of the load. In isolation each approach provides loading to within 20% of the predicted trend for only up to 50% of cases. However, a combined approach considering the SNR when greater than 0.2 enables the SNR method to calculate to within 20% of the predicted trend for 97% of cases. For the cases where the SNR value is less than 0.2, the predicted trend from the relationship between effective turbulence and normalised damage equivalent load, can predict the loads to within 20% for 88% of the cases.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104321"},"PeriodicalIF":3.4,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869787","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":"Modelling vegetation as complex structures in fluid–filament interaction using the elastically-articulated body method","authors":"Rufus E. Dickinson ,&nbsp;Timothy I. Marjoribanks ,&nbsp;Christopher J. Keylock ,&nbsp;Alessandro Palmeri","doi":"10.1016/j.jfluidstructs.2025.104323","DOIUrl":"10.1016/j.jfluidstructs.2025.104323","url":null,"abstract":"<div><div>Fluid–structure interactions in the built and natural environment commonly involve complex, heterogeneous structures. For example, terrestrial and aquatic vegetation species are morphologically complex, which is a factor not fully captured in many models used to understand important aspects of flow-vegetation dynamics. In this study, we develop and validate a multi-body method for modelling fluid interaction with slender structures (‘filaments’) in complex assemblies. This work uses Featherstone’s Articulated Body Algorithm to permit 3D simulation of connected assemblies of filaments. It includes development of an elasticity model for filament bending at large angles and a novel multi-body method for simulating the added mass effect. The model’s capabilities are validated through comparison with linear beam dynamics and three experimental studies of fluid–filament interaction from the literature. These are (1) flow-induced reconfiguration of heterogeneous and curved filaments, (2) resonance and flow-induced reconfiguration of filament assemblies and (3), wave-induced dynamics of a filament with added mass. The model is shown to be competitively accurate with existing filament dynamics models while extending modelling capability to multi-stem assemblages. Results from the model application demonstrate the importance of representing complex morphologies for accurately predicting flow-vegetation interactions.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104323"},"PeriodicalIF":3.4,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864088","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":"Large eddy simulation of tip and Karman vortices around a square prism: dynamic characteristics and their impact on lift force","authors":"Qingshan Yang ,&nbsp;Ling Zhao ,&nbsp;Wenshan Shan ,&nbsp;Kunpeng Guo ,&nbsp;Francesca Lupi ,&nbsp;Tong Zhou ,&nbsp;Xinyi Yue","doi":"10.1016/j.jfluidstructs.2025.104326","DOIUrl":"10.1016/j.jfluidstructs.2025.104326","url":null,"abstract":"<div><div>As a crucial component in the wind resistance design framework, flow-around analysis plays an essential role in assessing wind effects on structures. In this study, the dynamic behavior of tip- and Karman vortex around a ground-mounted finite length square prism (with an aspect ratio <em>H</em>/<em>B</em> = 9) subjected to atmospheric boundary layer flow representative of suburban terrain, and their relationship to lift force are investigated using large eddy simulation (LES). The Reynolds number based on the square prism width and incoming velocity is <span><math><mrow><mtext>Re</mtext><mo>=</mo><mn>3.0</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mn>4</mn></msup></mrow></math></span>. By combining with multiple-point synchronous pressure measurements and particle image velocimetry (PIV) wind tunnel tests, as well as other existing research, the wind loads characteristics are thoroughly examined from the perspective of mean and fluctuating wind pressure distribution on the model surface, local aerodynamic force distribution and overturning moments. Through time- and frequency domain analysis, two distinct lift fluctuation patterns are identified. The three-dimensional vortex structure analysis reveals that the Low-Amplitude Fluctuation (LAF) and High-Amplitude Fluctuation (HAF) of the lift force correspond to symmetrical and alternating vortex-shedding patterns, respectively. Symmetrical vortex shedding is primarily influenced by the downwash of tip vortex, while alternating vortex shedding pattern is driven by the Karman vortex. The notable differences in lift force fluctuation characteristics at various spanwise positions are associated with the range of influence exerted by the tip vortex downwash near the top of the square prism. The identification of the two lift force fluctuation patterns has practical implications for wind load assessment and structural design.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"136 ","pages":"Article 104326"},"PeriodicalIF":3.4,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864089","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":"Wind turbulence around a bridge deck in full scale","authors":"Nicolò Daniotti ,&nbsp;Jasna B. Jakobsen ,&nbsp;Jonas T. Snæbjörnsson ,&nbsp;Etienne Cheynet","doi":"10.1016/j.jfluidstructs.2025.104313","DOIUrl":"10.1016/j.jfluidstructs.2025.104313","url":null,"abstract":"<div><div>This paper studies the interaction between atmospheric turbulence and a closed-box bridge girder using new data acquired on the Lysefjord Bridge in Norway. Two sonic anemometers installed near the deck edges provided wind turbulence data, which were compared to observations of the incoming flow. The investigation provides insights into the distortion of natural wind both upstream and downstream of the deck, and the vortex-shedding process past the deck’s leeward side. In the near-wake region, the pronounced three-dimensionality of the flow was identified and its correlation with the yaw angle of the incident flow was established. Vertical velocity fluctuations served as an indicator of the vortex shedding process, and Strouhal number estimates were found to exhibit a certain sensitivity to the turbulence intensity in the approaching flow. The results discussed contribute to advancing the understanding of full-scale bridge aerodynamics and provide valuable data for validating and improving wind load models. The findings have implications for the design and safety of long-span bridges exposed to atmospheric turbulence.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"135 ","pages":"Article 104313"},"PeriodicalIF":3.4,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851672","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}