Journal of Fluids and Structures最新文献

{"title":"On the oscillatory behavior of two pendulum-like tandem circular slender cylinders","authors":"Patrick Batista Habowski ,&nbsp;Sergio Viçosa Möller ,&nbsp;Adriane Prisco Petry ,&nbsp;Atef Mohany","doi":"10.1016/j.jfluidstructs.2025.104424","DOIUrl":"10.1016/j.jfluidstructs.2025.104424","url":null,"abstract":"<div><div>This experimental study investigates the flow–structure interaction of two identical tandem slender cylinders subjected to cross-flow in a wind tunnel. The upstream and downstream cylinders were mounted in a pendulum-like configuration, allowing only transverse oscillation with matching natural frequencies, and were also tested in a fixed configuration for comparison purposes. All experiments were performed at spacing ratios ranging from 2.0 to 7.5, within a Reynolds number range of 16,000 to 22,000. Lateral displacements were recorded using a high-speed camera, and flow structures were analyzed using Particle Image Velocimetry (PIV). The primary objective was to correlate the observed flow dynamics from the PIV results with the oscillatory behavior of the cylinders. The results show that oscillations occurred for all investigated spacing ratios, with the most significant oscillations observed at a spacing ratio of 2.0 and a distinctive pattern with extreme amplitudes at a spacing ratio of 3.5. Cross-correlation of the Discrete Wavelet Transform of the vibration response reveals that the vibration of the downstream cylinder are influenced by the wake of the upstream cylinder, with its amplitude remaining enveloped within the wake of the upstream cylinder. The flow structure driving the oscillatory behavior indicates that the vibrations of the cylinders are predominantly governed by wake-induced vibration, except for the case of <span><math><mrow><mi>L</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>3</mn><mo>.</mo><mn>5</mn></mrow></math></span>, where a galloping-like instability was observed—a mechanism not previously reported for this configuration. The phenomenon described in this paper presents potential opportunity for energy harvesting applications.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104424"},"PeriodicalIF":3.5,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222496","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":"Study on the high-speed shallow-angle water entry of cylinders with varying densities","authors":"Xuepu Yan ,&nbsp;Shuai Sun ,&nbsp;Mo Zhu ,&nbsp;Tengfei Xu ,&nbsp;Pengfei Liu ,&nbsp;Zeqing Guo","doi":"10.1016/j.jfluidstructs.2025.104429","DOIUrl":"10.1016/j.jfluidstructs.2025.104429","url":null,"abstract":"<div><div>An investigation into the transient fluid-structure interactions during the high-speed (600 m/s) shallow-angle (8°) water entry of cylindrical projectiles with varying densities (2.7-16.1 g/cm³) is presented. The fundamental mechanisms governing cavity dynamics and projectile stability are revealed using three-dimensional computational fluid dynamics (CFD) simulations, which are validated by synchronized high-speed imaging. The key findings demonstrate that asymmetric wetting of the cylinder’s head during the early stage of water entry induces a critical head-down moment that governs subsequent hydrodynamic behavior. Three distinct fluid dynamic mechanisms are identified: 1) Delayed upper cavity formation accompanied by asymmetric cavity expansion; 2) Splash convergence producing distinct upward and downward jets, with the latter inducing localized cavity collapse upon impacting the wall; and 3) Pressure redistribution at the head end caused by variations in angle of attack, which generates restoring moments through asymmetric flow patterns. Density-dependent kinematic analysis reveals that within the same range of horizontal displacement, low-density cylinders (<em>ρ</em>≤4.1 g/cm³) undergo multiple tail slaps, whereas high-density cylinders (<em>ρ</em>≥7.2 g/cm³) achieve rotational stabilization through head-end restoring moments prior to tail slap initiation. Quantitative analysis shows that increasing the density from 2.7 to 16.1 g/cm³ reduces the maximum angular deflection by 89.43 % and the accumulated trajectory curvature by 42.83 %. These findings establish material density as the primary control parameter for ricochet prevention during shallow-angle water entry.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104429"},"PeriodicalIF":3.5,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221835","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":"A low-cost morphing vehicle design for enhanced aerodynamic performance","authors":"Sina Kazemipour,&nbsp;Peng Zhang","doi":"10.1016/j.jfluidstructs.2025.104422","DOIUrl":"10.1016/j.jfluidstructs.2025.104422","url":null,"abstract":"<div><div>Mid- and large-size road vehicles are responsible for high levels of green-house gas emissions, due to their poor aerodynamic designs. To alleviate this environmental and health risk, we propose a low-cost, noninvasive morphing vehicle design toward improved aerodynamic efficiency and reduced emissions. Using a generic pickup truck as the base geometry, morphing is accomplished by retrofitting a flexible structure over its cargo bed region, enabling active deformation and interaction with the airflow. The shape morphing process is optimized through a combined parametric genetic algorithm – computational fluid dynamics framework, enabling continuous morphing across a range of driving speeds. The optimal structural shapes lead to a reduction in the aerodynamic drag force between 8.7% and 10.1%. Analysis of the airflow physics reveals that the morphing structure compresses the size of the circulation bubble and reduces the strength of the counter-rotating flow structures in the wake, resulting in increased wake pressure and decreased drag force. Remarkably, the morphing structure not only reduces the drag on the base vehicle geometry but also elicits a negative drag force on itself. This non-invasive morphing vehicle design concept could transform the automotive industry by enhancing fuel economy and reducing emissions for existing vehicle models.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104422"},"PeriodicalIF":3.5,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159583","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":"Hydrodynamic behavior of an offshore OWC power station under dam-break flows: Numerical and experimental study","authors":"Shiqi Pan ,&nbsp;Haochen Zhang ,&nbsp;Jing Geng ,&nbsp;Xuanlie Zhao","doi":"10.1016/j.jfluidstructs.2025.104426","DOIUrl":"10.1016/j.jfluidstructs.2025.104426","url":null,"abstract":"<div><div>The hydrodynamic behavior of a three-dimensional oscillating water column (OWC) device subjected to dam-break flow incidents was investigated using numerical and experimental methods. Load characteristics and flow field distributions were analyzed under various opening ratios of the air chamber and angles of incident flow. Numerical results were validated against experimental measurements of impact loads and water surface elevation at a 45° incident angle, and extended to six additional incident angles: 0°, 15°, 30°, 60°, 75°, and 90°. The peak impact load and air chamber pressure occurred at 90°, both decreasing as the incident angle varied to 0°. The peak horizontal resultant force decreased by 43.4 %, 55.3 %, and 65.9 % at 60°, 45°, and 30°, respectively, while peak air pressure decreased by up to 68 % at 0°. Loads on internal and external walls were of similar magnitudes, highlighting the importance of considering internal wall forces in structural design. Flow field analysis revealed complex flow contours and an inclined water surface inside the chamber, which became more pronounced as the incident angle decreased. Moreover, increasing the opening ratio of the air chamber significantly reduced peak impact loads and air pressure, especially in the range of 0 % to 3.5 %. However, larger opening ratios may reduce energy capture efficiency. Thus, selecting an appropriate opening ratio that balances load reduction with energy capture efficiency is crucial for OWC design.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104426"},"PeriodicalIF":3.5,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159582","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":"Shifting aeroacoustic source mechanisms of a transversely oscillating cylinder in lock-in region at various Mach numbers","authors":"Fangcheng Shi ,&nbsp;Hongpeng Liu ,&nbsp;Dongrun Liu ,&nbsp;Tiantian Wang","doi":"10.1016/j.jfluidstructs.2025.104425","DOIUrl":"10.1016/j.jfluidstructs.2025.104425","url":null,"abstract":"<div><div>Direct numerical simulation of the aerodynamic noise generated by a flow past a transversely oscillating cylinder is conducted to investigate the effect of Mach number on the aeroacoustic characteristics. The results indicate that the coupling between the oscillating motion and vortex shedding in the lock-in region leads to a distribution of the surface pressure pulsation time derivative with four distinct peaks. The intensity of the radiated noise from the oscillating cylinder in the lock-in region is reduced compared to the stationary case. Although the oscillating frequency associated with this noise reduction is insensitive to Mach number, the reduction effect weakens at high Mach numbers. Furthermore, as the Mach number increases, the sound directivity at the lock-in boundary transitions from a figure-eight configuration to a butterfly-like configuration, featuring distinct lobes both upstream and downstream. To illustrate the changes in noise, the key finding is the modified scaling law governing noise intensity in relation to Mach number for the oscillating cylinder: it shifts from <span><math><msup><mrow><mi>M</mi></mrow><mrow><mn>2</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span> to <span><math><msup><mrow><mi>M</mi></mrow><mrow><mn>3</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span>, characteristic of quadrupole sources. This alteration is further analyzed by applying the Ffowcs Williams-Hawkings equation to separate the contributions of different noise sources, and utilizing spectral proper orthogonal decomposition to extract the dominant coherent structures responsible for the oscillating cylinder at the lock-in boundary at high Mach numbers.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104425"},"PeriodicalIF":3.5,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145120993","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":"Aerodynamic admittance and dynamics of an open-grown tree","authors":"Xiaonan Wang ,&nbsp;Jakob Mann ,&nbsp;Ebba Dellwik ,&nbsp;Nikolas Angelou","doi":"10.1016/j.jfluidstructs.2025.104409","DOIUrl":"10.1016/j.jfluidstructs.2025.104409","url":null,"abstract":"<div><div>Enhancing our understanding of the structural response of trees exposed to wind loading is important, since the knowledge of their aerodynamic behaviour is necessary for a realistic risk assessment of tree damage during extreme wind conditions. Here, we first present an analytical model of the aerodynamic admittance function that relates the turbulence fluctuations of the wind at a single point to their spatial average over the crown’s frontal area. The latter is responsible for the wind-induced bending moments at the base of a tree’s stem. We employ the aerodynamic admittance function to model the dynamic structural response of an open-grown oak tree. The analysis is performed along two axes to express both the longitudinal and transverse response with respect to the mean wind direction. The resulting predictions are compared with strain gauge observations taken at the lower part of the stem. The presented framework shows that the spatial averaging over the crown’s frontal area has a stronger effect on the tree’s movements in the streamwise wind direction compared to the spanwise direction. Further, the aerodynamic damping is also stronger in the streamwise direction and generally correlates positively with the inflow wind speed.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104409"},"PeriodicalIF":3.5,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145120995","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":"Sequential learning based PINNs to overcome temporal domain complexities in unsteady flow past flapping wings","authors":"Rahul Sundar ,&nbsp;Didier Lucor ,&nbsp;Sunetra Sarkar","doi":"10.1016/j.jfluidstructs.2025.104421","DOIUrl":"10.1016/j.jfluidstructs.2025.104421","url":null,"abstract":"<div><div>For a data-driven and physics combined modeling of unsteady flow systems with moving immersed boundaries, Sundar <em>et al.</em> (Sundar et al. 2024) introduced an immersed boundary-aware (IBA) framework, combining Physics-Informed Neural Networks (PINNs) and the immersed boundary method (IBM). This approach was beneficial because it avoided case-specific transformations to a body-attached reference frame. Building on this, we now address the challenges of long time integration in velocity reconstruction and pressure recovery by extending this IBA framework with sequential learning strategies. Key difficulties for PINNs in long time integration include temporal sparsity, long temporal domains and rich spectral content. To tackle these, a moving boundary-enabled PINN is developed, proposing two sequential learning strategies: - a time marching with gradual increase in time domain size, training a monolithic PINN and - a time decomposition which divides the temporal domain into smaller segments, training a PINN over each subdomains and combining them together. While the former approach may struggle with error accumulation over long time domains, the latter one, eventually combined with transfer learning, effectively reduces error propagation and computational complexity. The key findings for modeling of incompressible unsteady flows past a flapping airfoil include: - for quasi-periodic flows, the time decomposition approach with preferential spatio-temporal sampling improves accuracy and efficiency for pressure recovery and aerodynamic load reconstruction, and, - for long time domains, decomposing it into smaller temporal segments and employing multiple sub-networks, simplifies the problem ensuring stability and reduced network sizes. This study highlights the limitations of traditional PINNs for long time integration of flow-structure interaction problems and demonstrates the benefits of decomposition-based strategies for addressing error accumulation, computational cost, and complex dynamics.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104421"},"PeriodicalIF":3.5,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145120994","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":"Active flow control of vertical-axis wind turbines: Insights from large-eddy simulation and finite-time resolvent analysis","authors":"Lucas Feitosa de Souza,&nbsp;Renato Fuzaro Miotto,&nbsp;William Roberto Wolf","doi":"10.1016/j.jfluidstructs.2025.104410","DOIUrl":"10.1016/j.jfluidstructs.2025.104410","url":null,"abstract":"<div><div>Active flow control is applied to improve the aerodynamic performance of a NACA0018 airfoil operating as a single-bladed vertical axis wind turbine (VAWT). Results computed by wall-resolved large-eddy simulations (LES) highlight the detrimental effects of the dynamic stall vortex (DSV) and trailing-edge vortex (TEV) on turbine efficiency, primarily through increased drag and energy loss. The proposed flow control strategy effectively delays flow separation and suppresses large-scale vortex formation, particularly at moderate actuation frequencies. The control parameters are grounded in bi-global stability and finite-time resolvent analyses. These techniques identify the excitation of coupling modes between shear layer and wake instabilities as a mechanism for promoting flow reattachment and preventing vorticity accumulation, ultimately leading to enhanced torque production. The control strategy is energy-efficient, consuming only 1% of the turbine’s output power while yielding substantial aerodynamic performance gains. These findings demonstrate the promise of physics-informed active flow control in mitigating dynamic stall and advancing the design of next-generation VAWTs.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104410"},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145109411","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":"Coupled fluid–structure simulations of a cantilever rod in water turbulent axial flow with different CFD approaches","authors":"Daniele Vivaldi,&nbsp;Roxan Pulicani","doi":"10.1016/j.jfluidstructs.2025.104412","DOIUrl":"10.1016/j.jfluidstructs.2025.104412","url":null,"abstract":"<div><div>Fluid–structure numerical simulations of an experimental campaign by Cioncolini et al. of a cantilever rod in water axial flow were performed. The experimental configuration aims at representing a nuclear fuel rod, in terms of hydraulic diameter. Water velocity profiles and structure vibrations were measured experimentally. Two of the experimental tests were simulated numerically, one at Re=1.5<span><math><mi>⋅</mi></math></span>10⁴ and one at Re=1.9<span><math><mi>⋅</mi></math></span>10⁴. Different CFD approaches were tested, using code_Saturne: a wall-resolved two-equation linear viscosity model (k-<span><math><mi>ω</mi></math></span>-SST), two wall-modeled Reynolds stress models (SSG and LRR), a wall-resolved Reynolds stress model (EBRSM) and a wall-resolved hybrid URANS/LES model (DDES). The structure was simulated through a one-dimensional finite element Euler–Bernoulli beam model. A 2-way coupling was implemented between the two solvers, with an Arbitrary Lagrangian Eulerian approach. Unexpectedly, wall-modeled Reynolds-stress models were found to calculate higher amplitudes of vibration than the higher-resolution EBRSM and DDES. The frequency domain analysis allowed to identify high energy flow velocity and flow-induced force harmonics at relatively low frequency calculated by LRR and SSG, not present in the EBRSM and DDES results, which explain the numerical results in terms of vibration response. This specific behavior of LRR and SSG seems to be linked to the wall function boundary condition. LRR and SSG calculate a rms amplitude of vibration close to the experiments, whereas EBRSM and DDES underestimate them by a factor of 2.5. A hypothetical small permanent deformation (4% of the hydraulic diameter) of the rod was simulated and found to increase the calculated vibration amplitudes by a factor of 2. 1-way coupling was also tested to assess the influence of damping and added mass on the results.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104412"},"PeriodicalIF":3.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107825","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":"Surface bulk cavity formation on flat isotropic plates subjected to near-field underwater explosions","authors":"Carlos Javier ,&nbsp;Michael Galuska ,&nbsp;James LeBlanc ,&nbsp;Helio Matos ,&nbsp;Arun Shukla","doi":"10.1016/j.jfluidstructs.2025.104420","DOIUrl":"10.1016/j.jfluidstructs.2025.104420","url":null,"abstract":"<div><div>The formation of surface bulk cavities on isotropic flat plates due to the detonation of a near-field underwater explosive (UNDEX) has been computationally investigated. Experiments were performed in an air-backed condition for polycarbonate plates of 6.35 mm thickness, and 12.70 mm thickness, as well as steel plates 12.70 mm in thickness. Moreover, three distances between the explosive and targets were selected. Numerical simulations were performed with the fully coupled Eulerian–Lagrangian fluid structure interaction code Dynamic System Mechanics Advanced Simulation (DYSMAS). Initially, the numerical simulations were validated with the experimental data. Once validated, the numerical simulations were utilized to explore a wide range of structures and standoff distances. Results show that a surface bulk cavity forms on the plate when the centerpoint out of plane velocity of the plate reaches its maximum magnitude while the plate displaces towards the UNDEX gas bubble. Moreover, plates with equal flexural stiffness attained comparable maximum surface bulk cavity volumes. Additionally, the maximum surface bulk cavity volume exponentially decreases as the plate’s flexural stiffness increases. The maximum volume attained by the UNDEX gas bubble is directly related to the timing in which the surface bulk cavity begins to form on the plate. This timing is related to the plate’s flexural stiffness, as well as the plate’s natural frequency. The loading on the plate resulting from the collapse of the surface bulk cavity and the UNDEX gas bubble are influenced by the plate’s flexural stiffness.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104420"},"PeriodicalIF":3.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107824","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}