Journal of Fluids and Structures最新文献

{"title":"Snap-through oscillations of an elastic sheet for enhanced heat transfer in dual-channel systems","authors":"Jingyu Cui ,&nbsp;Yansong Li ,&nbsp;Yuzhen Jin ,&nbsp;Xianghui Su ,&nbsp;Zhaokun Wang","doi":"10.1016/j.jfluidstructs.2025.104407","DOIUrl":"10.1016/j.jfluidstructs.2025.104407","url":null,"abstract":"<div><div>This study explores the use of the snap-through behavior of an elastic sheet as a vortex generator (VG) to enhance heat transfer in a dual-channel system. By leveraging snap-through oscillations, a single sheet clamped at the common wall of the dual channels can simultaneously enhance heat transfer in both channels with a reduced pressure drop. The thermohydraulic performance is analyzed using the immersed boundary-lattice Boltzmann method across varying system parameters. The results demonstrate that for a given Reynolds number (<em>Re</em>), the sheet can operate in either a snap-through mode or dormant mode, depending on its buckled length and bending stiffness (<em>EI*</em>). The snap-through mode achieves superior heat transfer performance, especially at lower bending stiffness, with a thermal efficiency factor (<em>η</em>) of 1.3 at <em>EI*</em> = 0.002, outperforming the wall-clamped flag configuration by 5% and the rigid VG by 14.5%. Comparative analysis reveals that, while the wall-clamped flag configuration is more effective at higher bending stiffness, the proposed VG excels at lower bending stiffness, making these configurations complementary across different applications. The performance of the VG can be further adjusted by modifying the buckled distance of the sheet, with <em>η</em> decreasing as the buckled length increases. Additionally, as <em>Re</em> rises, oscillation-induced flow separation intensifies, further enhancing convective heat transfer. At <em>Re</em> = 1000, <em>η</em> exceeds 1.4, demonstrating robust performance in high-<em>Re</em> regimes. These findings highlight the VG’s potential for tunable and efficient heat transfer enhancement in dual-channel applications.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104407"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879784","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":"Geometrically exact mechanics of pipes conveying fluid with an axially sliding downstream end","authors":"Amir Mehdi Dehrouyeh-Semnani","doi":"10.1016/j.jfluidstructs.2025.104402","DOIUrl":"10.1016/j.jfluidstructs.2025.104402","url":null,"abstract":"<div><div>In this study, the post-buckling patterns and stability characteristics of hanging and standing soft pipes conveying fluid, with an axially sliding downstream end, are investigated using a new nonlinear geometrically exact model. The mathematical formulation in terms of the rotation angle and lateral displacement, is derived by incorporating the lateral constraint at the downstream end into the geometrically exact model of a cantilevered pipe conveying fluid in terms of the rotation angle. Additionally, a linearized mathematical model of the system around its post-buckling path is established to assess the stability characteristics of post-buckled configurations. To determine the post-buckling patterns and their stability behavior, the shooting scheme in conjunction with the Runge-Kutta finite difference method is utilized. The analysis focuses on both hanging and standing systems, where the downstream end is simply supported and the upstream end may be either clamped or simply supported, taking into account the simultaneous influences of flow velocity and gravity. Furthermore, in the case of the standing system with both ends simply supported, the potential for snap-through buckling is examined. Ultimately, the geometrically exact patterns are compared with those obtained by the original and approximate versions of the nonlinear third-order model.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104402"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893807","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":"Low-frequency bandgap widening and detuning analysis in fluid-filled pipes with periodic parallel supports","authors":"Wenjie Li ,&nbsp;Xiangxi Kong ,&nbsp;Qi Xu ,&nbsp;Ziyu Hao ,&nbsp;Jingqiao Wang ,&nbsp;Zhilin Wang","doi":"10.1016/j.jfluidstructs.2025.104404","DOIUrl":"10.1016/j.jfluidstructs.2025.104404","url":null,"abstract":"<div><div>Most existing periodic pipelines require significant modifications to their main structure or inevitably add extra weight, which inconveniences engineering applications and results in poor low-frequency performance. This paper presents a parallel support strategy based on periodic elastic supports that achieve broadband control of low-frequency vibrations in fluid-filled pipes. It also discusses the concept of periodic detuning. Firstly, a parallel support cell structure is designed, and the system model is developed according to Hamilton's principle and Euler-Bernoulli's theory. Secondly, the composite cell is segmented, and the bandgap is calculated using the spectral element method. The Galerkin method is employed for discretization, while the Runge-Kutta method is utilized to solve stable responses, with the transmission loss function defined accordingly. Then, the accuracy of the equivalent stiffness and bandgap is verified through comparisons with previous data and COMSOL simulations. Finally, a detailed discussion is provided on the bandgap widening and characteristics of periodic parallel-supported fluid-filled pipes. The effects of single-factor and coupled detuning on these periodic pipes are analyzed, followed by the construction and validation of an experimental platform. The experimental results indicate that the periodic parallel support significantly widens the bandgap. Moreover, appropriate detuning can expand the frequency range for vibration attenuation. This research offers valuable insights into the engineering applications of periodic pipelines and introduces a novel \"detuning\" approach for bandgap widening.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104404"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830330","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":"Blade vibration reduction of a nozzleless radial turbine by casing treatment","authors":"Zhaokai Lu ,&nbsp;Yingyuan Wang ,&nbsp;Mingyang Yang ,&nbsp;Xianfeng Wang","doi":"10.1016/j.jfluidstructs.2025.104408","DOIUrl":"10.1016/j.jfluidstructs.2025.104408","url":null,"abstract":"<div><div>High cycle fatigue (HCF) is the most common form of blade failure in nozzleless radial turbines. Current studies on blade vibration reduction primarily focus on the blade design optimization and geometry modifications, typically at the cost of increased rotor weight and reduced aerodynamic performance. This paper investigates a novel flow control method for blade vibration reduction based on casing treatment. Inspired by the generalized force method, casing treatment is proposed to offset the excitation caused by volute. Axial grooves are introduced on the casing (named casing treatment) to reduce blade excitation caused by volute, with particular emphasis on high-expansion-ratio conditions due to the large vibration amplitude. Firstly, the influence of relative position of volute tongue and grooves on blade excitation is investigated via well-validated one-way Fluid-Structure Interaction (FSI) method. Results show that the vibration amplitude can be significantly reduced without sacrificing aerodynamic performance by adjusting the relative position appropriately. Generalized force and flow field analysis reveal that the generalized forces induced by the volute and the groove offset each other when positioned correctly. Secondly, the influence of size parameters of casing treatment on blade excitation is investigated. Two of the parameters only influence the length of generalized force caused by casing treatment rather than the phase, which greatly simplifies and facilitates the optimum design of casing treatment. Numerical results suggest that the blade vibration amplitude can be reduced by up to 94 % at high pressure ratio via the optimum design of the casing treatment. The effect of optimum casing treatment under various pressure ratios is also investigated. The optimum design has satisfied effect at high pressure ratio, but further optimization is required under low pressure ratio conditions. Finally, the effectiveness of the casing treatment is validated via tip-timing experiments, demonstrating a significant reduction in blade amplitude by 48 % under the most critical operating conditions.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104408"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907204","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 identification of blade-level forces, torque, and pitching moment for cross-flow turbines","authors":"Abigale Snortland ,&nbsp;Katherine Van Ness ,&nbsp;Jennifer A. Franck ,&nbsp;Ari Athair ,&nbsp;Owen Williams ,&nbsp;Brian Polagye","doi":"10.1016/j.jfluidstructs.2025.104403","DOIUrl":"10.1016/j.jfluidstructs.2025.104403","url":null,"abstract":"<div><div>Cross-flow turbine power is a net sum of power generation from rotating blades and power loss from rotating support structures. While the aggregate forces and torques at the turbine level are important for end use, these can inhibit a deeper understanding of fluid–structure interactions. Identification of blade-level forces and torques allows for specific investigations into how the fluid forcing on the blade drives rotation and can aid blade structural design. Here, we present a physics-based methodology for extracting blade-level forces and torques from experimental measurements at the axis of rotation of a cross-flow turbine, and demonstrate strong agreement with equivalent blade-only simulations. In doing so, we highlight the often-overlooked pitching moment, which offsets continuous increases in power generation from the tangential force and leads to net-zero power generation at freewheel.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104403"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863904","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 parametric study of a flap-NES passive absorber for post-flutter control","authors":"Jesús García Pérez ,&nbsp;Leonardo Sanches ,&nbsp;Amin Ghadami ,&nbsp;Bogdan I. Epureanu ,&nbsp;Guilhem Michon","doi":"10.1016/j.jfluidstructs.2025.104405","DOIUrl":"10.1016/j.jfluidstructs.2025.104405","url":null,"abstract":"<div><div>Aeroelastic instabilities present significant challenges in aircraft design, particularly for novel designs leveraging high aspect ratios and flexible wings to enhance aerodynamic efficiency. These advancements, seen in both high-altitude, high-endurance aircraft and commercial airliners, introduce complexities such as low resonant frequencies and increased susceptibility to aeroelastic instabilities, particularly flutter, which can lead to structural failure. The current certification process requires aircraft to be free from flutter within the operational flight envelope and beyond it, typically with a safety margin of 15% Various strategies have been explored to mitigate flutter and expand the flight envelope. In this work, passive vibration mitigation is applied to an experimental aeroelastic system exhibiting complex aeroelastic instabilities in a wind tunnel. The system consists of a rigid wing mounted on elastic supports with a flap that spans one-third of the wingspan and acts as an innovative nonlinear passive absorber. The setup includes pitch stiffness nonlinearity, which contributes to complex aeroelastic responses such as subcritical flutter and limit cycle oscillations. This solution benefits from aerodynamic damping and adds a very small amount of mass to the system. The main focus of this paper is to assess the influence of flap-NES parameters on aeroelastic behavior and to explore its potential impact on different wing configurations. Results show a delay in the onset of instability up to 34% in airspeed, a suppression of large amplitude vibrations due to stall flutter, and a removal of subcritical behavior.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104405"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893861","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":"Enhanced vortex-induced vibration prediction of marine risers using excitation coefficient databases at high Reynolds numbers","authors":"Jiawei Shen,&nbsp;Pengqian Deng,&nbsp;Shixiao Fu,&nbsp;Xuepeng Fu,&nbsp;Leijian Song,&nbsp;Yuwang Xu","doi":"10.1016/j.jfluidstructs.2025.104406","DOIUrl":"10.1016/j.jfluidstructs.2025.104406","url":null,"abstract":"<div><div>Current methods for predicting vortex-induced vibration (VIV) of marine risers mainly depend on excitation coefficient databases obtained from forced vibration experiments on a rigid cylinder at a low Reynolds number (Re = 1.0E4). However, investigations at higher Reynolds numbers have revealed notable effects on VIV behaviors, resulting in discrepancies when predictions are based on previous experimental databases. To resolve this, forced vibration experiments were carried out on a rigid cylinder model over a Reynolds number range of 5.0E4 to 3.5E5. The acquired data enabled the development of comprehensive excitation coefficient databases covering both subcritical and critical Re regimes. A non-iterative frequency-domain prediction method integrating the updated excitation coefficient databases was proposed and validated through experiments on a flexible riser model. Subsequently, predictive calculations were conducted to investigate the effects of the Reynolds numbers in the excitation coefficient databases on the prediction outcomes. Comparative analysis shows that method based on a higher subcritical Reynolds number (2.0E5) tend to predict larger vibration amplitudes and amplified fatigue damage, whereas those corresponding to critical Reynolds numbers (3.0E5 and 3.5E5) indicate lower amplitudes and reduced fatigue damage. These findings underscore the importance of using excitation coefficient databases that match the relevant Reynolds number conditions to mitigate the risks of overly optimistic or conservative marine riser designs.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104406"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894905","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":"Corrigendum to \"Flow-induced vibration of an underwater lazy wave cable in unidirectional current\" Journal of Fluids and Structures 137 (2025) 104385/YJFLS 104385 https://doi.org/10.1016/j.jfluidstructs.2025.104385","authors":"R. Moideen ,&nbsp;V. Venugopal ,&nbsp;J.R. Chaplin ,&nbsp;A.G.L. Borthwick","doi":"10.1016/j.jfluidstructs.2025.104401","DOIUrl":"10.1016/j.jfluidstructs.2025.104401","url":null,"abstract":"","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104401"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048960","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":"Mitigating unsteady loads at low Reynolds numbers using a passive trailing-edge flap","authors":"C. Martínez-Muriel ,&nbsp;I.M. Viola ,&nbsp;M. García-Villalba ,&nbsp;O. Flores","doi":"10.1016/j.jfluidstructs.2025.104392","DOIUrl":"10.1016/j.jfluidstructs.2025.104392","url":null,"abstract":"<div><div>The load mitigation potential of a passive pitching trailing edge flap for NACA0012 airfoils at a Reynolds number of 1000 subjected to oscillations in the angle of attack is analyzed. For this purpose, direct numerical simulations of the two-dimensional, incompressible flow have been conducted to examine the effectiveness of the flap in reducing aerodynamic load fluctuations across a range of oscillation amplitudes and flap-to-chord ratios. The validity of a quasi-steady model to predict the load mitigation using passive pitching flaps, previously proposed in the literature and predicting a load mitigation proportional to the flap-to-chord length ratio, <span><math><mrow><mi>a</mi><mo>/</mo><mi>c</mi></mrow></math></span>, is here investigated for large amplitude oscillations. The results show that the increment in the reduction in fluctuations is generally proportional to the increment in <span><math><mrow><mi>a</mi><mo>/</mo><mi>c</mi></mrow></math></span>. This closely aligns with the predictions of the quasi-steady theory, even for the cases with the largest oscillation amplitudes, where non-linear aerodynamic effects are present, although some variation is observed. Notably, we explored the interaction between vortical structures and the flap dynamics, and its relevance on the flow patterns around the airfoil and ultimately on load mitigation. This interaction, alongside flap inertia, provides insight into the timing and magnitude of load reduction, demonstrating the potential of tailored passive pitching mechanisms for unsteady flow conditions. These findings offer valuable insights for the design and development of passive unsteady load mechanisms for small aerial and underwater vehicles, as well as microscale energy harvesters, by highlighting the relevance of considering non-linear effects in their optimization.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104392"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879783","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":"Mechanism of the sharp rise and fall of the impact force during water impact of a flat plate: compression-expansion behavior of trapped air layer","authors":"Xiaohang Shi ,&nbsp;Qiulin Qu ,&nbsp;Peiqing Liu ,&nbsp;Jin Zhang ,&nbsp;Yunlong Zheng","doi":"10.1016/j.jfluidstructs.2025.104393","DOIUrl":"10.1016/j.jfluidstructs.2025.104393","url":null,"abstract":"<div><div>During the water impact of a flat plate, an air cushion is generally entrapped underneath and the impact force history is characterized by pronounced oscillations, typically comprising three distinct stages: a sharp rise to the peak, a sharp drop to the trough, and less intense pulsating forces thereafter. The physics of post-impact pulsating forces is full understood, i.e., due to bubble oscillations; whereas, a clear understanding of the initial sharp rise and fall of the impact force is still lacking, which is numerically investigated in this paper. The results show that the drastic compression-expansion behavior of the trapped air layer is the physical cause. By defining an air control volume confined by the moving plate bottom and its underneath deforming water surface, for the first time, we demonstrate that the compression-expansion mechanism of air layer is governed by two key physical processes: the contraction and expansion of the control volume, and the inflow and outflow of air through the control surface.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"138 ","pages":"Article 104393"},"PeriodicalIF":3.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780755","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}