Pub Date : 2025-12-23DOI: 10.1016/j.jfluidstructs.2025.104490
Simone Cruciani , Franco Auteri , Michel Fournié
We study the numerical stabilization around an unstable steady solution of a typical fluid-structure interaction problem constituted by a circular cylinder with a flexible splitter plate (Turek and Hron, 2006) actuated by piezoelectric devices and immersed in a fully developed, laminar channel flow. We define a linear feedback control that can locally stabilize the fully coupled nonlinear system. The feedback is based on a spectral decomposition of a non-standard Differential Algebraic Equation resulting from a monolithic Arbitrary Lagrangian Eulerian Finite Element formulation where a simple model of the piezoelectric patches is considered. By projecting the full system on its unstable subspace, a Reduced Order Model is defined. The design of the controlled system exploits the computation of the unstable direct and adjoint subspaces to identify the number and distribution of the patches on the beam. Moreover, the feasibility of such a controller for a real application is assessed by looking at the saturation limit of the control input. This paper is an extension of the methodology presented in Airiau et al. (2017) and Fournié et al. (2019) to control the Navier-Stokes equations to a fluid-structure model actuated by macro-fiber composites. To our knowledge, such active controls are original and the numerical tests presented validate their promising potential.
{"title":"Control of the channel flow past a cylinder by a piezo-actuated flexible splitter plate","authors":"Simone Cruciani , Franco Auteri , Michel Fournié","doi":"10.1016/j.jfluidstructs.2025.104490","DOIUrl":"10.1016/j.jfluidstructs.2025.104490","url":null,"abstract":"<div><div>We study the numerical stabilization around an unstable steady solution of a typical fluid-structure interaction problem constituted by a circular cylinder with a flexible splitter plate (Turek and Hron, 2006) actuated by piezoelectric devices and immersed in a fully developed, laminar channel flow. We define a linear feedback control that can locally stabilize the fully coupled nonlinear system. The feedback is based on a spectral decomposition of a non-standard Differential Algebraic Equation resulting from a monolithic Arbitrary Lagrangian Eulerian Finite Element formulation where a simple model of the piezoelectric patches is considered. By projecting the full system on its unstable subspace, a Reduced Order Model is defined. The design of the controlled system exploits the computation of the unstable direct and adjoint subspaces to identify the number and distribution of the patches on the beam. Moreover, the feasibility of such a controller for a real application is assessed by looking at the saturation limit of the control input. This paper is an extension of the methodology presented in Airiau et al. (2017) and Fournié et al. (2019) to control the Navier-Stokes equations to a fluid-structure model actuated by macro-fiber composites. To our knowledge, such active controls are original and the numerical tests presented validate their promising potential.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104490"},"PeriodicalIF":3.5,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840941","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}
Pub Date : 2025-12-22DOI: 10.1016/j.jfluidstructs.2025.104494
Zhen Xue , Chao Wang , Fajun Yu , Shaoyu Zhong
This study advances radiation hydrodynamics for cylindrical arrays in two-layer fluids, addressing critical challenges inherent to density-stratified systems. While existing methodologies effectively characterize wave interactions in uniform-density environments, the coupled surface-interface boundary conditions in stratified flows introduce three fundamental complexities: modal coupling between surface and internal waves governed by density () and depth () ratios, non-negligible evanescent modes in radiation processes, and nonlinear parametric dependencies of radiation forces on stratification parameters and geometric factors such as radius-to-depth ratio () and spatial arrangement. To resolve these challenges, a generalized hydrodynamic model is developed by integrating a modified stratified eigenfunction method with a multi-cylinder interference theory. This framework enables systematic quantification of hydrodynamic coefficients under both global and relative radiation motions, revealing the influence of geometric configurations, stratification parameters, and motion modalities. Parametric studies demonstrate the critical regulatory role of density ratio and interface elevation on radiation, particularly under internal wave dominance, while identifying phase-dependent amplification or attenuation effects of complex motion modes on added mass and damping coefficients in two-layer systems. Validated against classical homogeneous-fluid and stratified single-cylinder solutions, the model provides design insights for mitigating hydrodynamic loads in stratified marine environments. The work establishes a unified framework for predicting multi-body interactions in density-stratified flows, connecting homogeneous fluid theory with practical maritime engineering applications.
{"title":"Hydrodynamic radiation analysis of bottom-mounted cylinder arrays in two-layer fluids","authors":"Zhen Xue , Chao Wang , Fajun Yu , Shaoyu Zhong","doi":"10.1016/j.jfluidstructs.2025.104494","DOIUrl":"10.1016/j.jfluidstructs.2025.104494","url":null,"abstract":"<div><div>This study advances radiation hydrodynamics for cylindrical arrays in two-layer fluids, addressing critical challenges inherent to density-stratified systems. While existing methodologies effectively characterize wave interactions in uniform-density environments, the coupled surface-interface boundary conditions in stratified flows introduce three fundamental complexities: modal coupling between surface and internal waves governed by density (<span><math><mrow><mi>γ</mi><mo>=</mo><msub><mi>ρ</mi><mn>1</mn></msub><mo>/</mo><msub><mi>ρ</mi><mn>2</mn></msub></mrow></math></span>) and depth (<span><math><mrow><msub><mi>h</mi><mn>1</mn></msub><mo>/</mo><msub><mi>h</mi><mn>2</mn></msub></mrow></math></span>) ratios, non-negligible evanescent modes in radiation processes, and nonlinear parametric dependencies of radiation forces on stratification parameters and geometric factors such as radius-to-depth ratio (<span><math><mrow><mi>a</mi><mo>/</mo><mi>h</mi></mrow></math></span>) and spatial arrangement. To resolve these challenges, a generalized hydrodynamic model is developed by integrating a modified stratified eigenfunction method with a multi-cylinder interference theory. This framework enables systematic quantification of hydrodynamic coefficients under both global and relative radiation motions, revealing the influence of geometric configurations, stratification parameters, and motion modalities. Parametric studies demonstrate the critical regulatory role of density ratio and interface elevation on radiation, particularly under internal wave dominance, while identifying phase-dependent amplification or attenuation effects of complex motion modes on added mass and damping coefficients in two-layer systems. Validated against classical homogeneous-fluid and stratified single-cylinder solutions, the model provides design insights for mitigating hydrodynamic loads in stratified marine environments. The work establishes a unified framework for predicting multi-body interactions in density-stratified flows, connecting homogeneous fluid theory with practical maritime engineering applications.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104494"},"PeriodicalIF":3.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840943","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}
Pub Date : 2025-12-22DOI: 10.1016/j.jfluidstructs.2025.104492
Kanghui Zheng , Yukun Feng , Zuogang Chen , Yi Dai
In this study, the torsional motion induced by the aerodynamic instability in solar tracking systems was investigated through field modal testing, wind tunnel experiments, and computational fluid dynamics (CFD) simulations. First, modal testing was conducted on a full-scale solar tracking system to obtain the system's natural frequencies and damping ratios, which were used as input data for subsequent calculations. Second, aerodynamic instability experiments of the solar tracking system at the model scale were carried out, and the variations of the torsional angles with the wind speed at different installation angles were obtained. CFD simulations were also conducted under the same conditions, and the reliability of the CFD model was verified by comparing the simulation results with the experimental data. Third, CFD simulations were carried out on a full-scale solar tracking system to study the effects of two key parameters, the wind speed and the installation angle, on the aerodynamic instability. Critical wind speed curves for aerodynamic instability at different installation angles were obtained, and the flow mechanisms of the "torsional divergence" and "vortex lock-in" phenomena were summarized by analyzing the details of the flow field. Finally, the additional damping ratio's effect on suppressing torsional motion was evaluated. The results showed that the numerical model successfully simulated the entire process of the system's torsional divergence, with dynamic response characteristics that matched well with the experimental observations. For the full-scale model, at 0° installation angles, when the wind speed was below 44 m/s, flat-shaped vortex systems remained attached to the surface of the system. However, when the wind speed reached 45 m/s, alternating vortex shedding occurred on the upper and lower sides of the leading edge of the photovoltaic panel, intensifying the torsional motion of the solar tracking system. Continuous excitation ultimately led to an amplitude jump from within 10° to approximately 80°, resulting in the torsional divergence phenomenon and significantly increasing the risk of structural damage. When the installation angle was between 20° and 50°, vortex systems formed on the leeward side of the solar tracking system and alternately shed at the leading and trailing edges, creating the vortex lock-in phenomenon. This caused the vortex shedding frequency to remain almost unchanged within a certain wind speed range. Additionally, increasing the additional damping ratio from 0 % to 10 % had almost no effect on the critical wind speed at a 0° installation angle. For larger installation angles, increasing the damping ratio reduced the amplitude of torsional motion, thereby effectively increasing the critical wind speed. The results of this study provide a reference for the design and optimization of solar tracking systems, reducing the risk of structural damage to the system.
{"title":"Torsional motion study on the aerodynamic instability of solar tracking systems","authors":"Kanghui Zheng , Yukun Feng , Zuogang Chen , Yi Dai","doi":"10.1016/j.jfluidstructs.2025.104492","DOIUrl":"10.1016/j.jfluidstructs.2025.104492","url":null,"abstract":"<div><div>In this study, the torsional motion induced by the aerodynamic instability in solar tracking systems was investigated through field modal testing, wind tunnel experiments, and computational fluid dynamics (CFD) simulations. First, modal testing was conducted on a full-scale solar tracking system to obtain the system's natural frequencies and damping ratios, which were used as input data for subsequent calculations. Second, aerodynamic instability experiments of the solar tracking system at the model scale were carried out, and the variations of the torsional angles with the wind speed at different installation angles were obtained. CFD simulations were also conducted under the same conditions, and the reliability of the CFD model was verified by comparing the simulation results with the experimental data. Third, CFD simulations were carried out on a full-scale solar tracking system to study the effects of two key parameters, the wind speed and the installation angle, on the aerodynamic instability. Critical wind speed curves for aerodynamic instability at different installation angles were obtained, and the flow mechanisms of the \"torsional divergence\" and \"vortex lock-in\" phenomena were summarized by analyzing the details of the flow field. Finally, the additional damping ratio's effect on suppressing torsional motion was evaluated. The results showed that the numerical model successfully simulated the entire process of the system's torsional divergence, with dynamic response characteristics that matched well with the experimental observations. For the full-scale model, at 0° installation angles, when the wind speed was below 44 m/s, flat-shaped vortex systems remained attached to the surface of the system. However, when the wind speed reached 45 m/s, alternating vortex shedding occurred on the upper and lower sides of the leading edge of the photovoltaic panel, intensifying the torsional motion of the solar tracking system. Continuous excitation ultimately led to an amplitude jump from within 10° to approximately 80°, resulting in the torsional divergence phenomenon and significantly increasing the risk of structural damage. When the installation angle was between 20° and 50°, vortex systems formed on the leeward side of the solar tracking system and alternately shed at the leading and trailing edges, creating the vortex lock-in phenomenon. This caused the vortex shedding frequency to remain almost unchanged within a certain wind speed range. Additionally, increasing the additional damping ratio from 0 % to 10 % had almost no effect on the critical wind speed at a 0° installation angle. For larger installation angles, increasing the damping ratio reduced the amplitude of torsional motion, thereby effectively increasing the critical wind speed. The results of this study provide a reference for the design and optimization of solar tracking systems, reducing the risk of structural damage to the system.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104492"},"PeriodicalIF":3.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840942","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}
Pub Date : 2025-12-20DOI: 10.1016/j.jfluidstructs.2025.104487
H.A. Ma , Z.X. Xia , S.T. Gu , H.J. Liu , Y. Cong , H.P. Yin
Curved stiffened plates are frequently subjected to vibration challenges during their application in marine and underwater engineering structures. Traditional vibration mitigation strategies, such as increasing structural stiffness or incorporating high-damping materials, often lead to increased design complexity. In this study, a novel vibration reduction approach is proposed by designing periodic structures with appropriately arranged curved stiffeners. This approach leverages the unique band gap characteristics of periodic structures for vibration attenuation. A numerical framework is established for band gap analysis of arbitrarily curved stiffened plates, incorporating fluid-structure interaction (FSI) effects. Specifically, the constitutive model of the curved stiffened plate is derived using the Mindlin plate theory and Timoshenko beam theory. The fluid-structure interaction is modeled via the added mass method, and periodic boundary conditions are applied to both the plate and the fluid domains based on Bloch’s theorem. Numerical validation confirms the accuracy of the modal analysis for curved stiffened plates. The importance of properly arranging curved stiffeners was demonstrated through time-domain dynamic analyses of several finite structures, which also confirmed the effectiveness of the band gap. The influence of the fluid environment on the system’s band gap characteristics was thoroughly examined. Particular attention was given to how the amplitude, wavelength, and structural parameters of sinusoidal stiffeners affect the band gap, as well as the anisotropic propagation of elastic waves in sinusoidal stiffened plates. The results indicate that specific stiffener designs play a critical role in tuning band gap properties and enhancing structural vibration performance, offering valuable insights for vibration reduction in fluid-structure coupled curved stiffened plate applications.
{"title":"Numerical simulation of band gap characteristics of periodic curved stiffened plates considering fluid-structure interaction","authors":"H.A. Ma , Z.X. Xia , S.T. Gu , H.J. Liu , Y. Cong , H.P. Yin","doi":"10.1016/j.jfluidstructs.2025.104487","DOIUrl":"10.1016/j.jfluidstructs.2025.104487","url":null,"abstract":"<div><div>Curved stiffened plates are frequently subjected to vibration challenges during their application in marine and underwater engineering structures. Traditional vibration mitigation strategies, such as increasing structural stiffness or incorporating high-damping materials, often lead to increased design complexity. In this study, a novel vibration reduction approach is proposed by designing periodic structures with appropriately arranged curved stiffeners. This approach leverages the unique band gap characteristics of periodic structures for vibration attenuation. A numerical framework is established for band gap analysis of arbitrarily curved stiffened plates, incorporating fluid-structure interaction (FSI) effects. Specifically, the constitutive model of the curved stiffened plate is derived using the Mindlin plate theory and Timoshenko beam theory. The fluid-structure interaction is modeled via the added mass method, and periodic boundary conditions are applied to both the plate and the fluid domains based on Bloch’s theorem. Numerical validation confirms the accuracy of the modal analysis for curved stiffened plates. The importance of properly arranging curved stiffeners was demonstrated through time-domain dynamic analyses of several finite structures, which also confirmed the effectiveness of the band gap. The influence of the fluid environment on the system’s band gap characteristics was thoroughly examined. Particular attention was given to how the amplitude, wavelength, and structural parameters of sinusoidal stiffeners affect the band gap, as well as the anisotropic propagation of elastic waves in sinusoidal stiffened plates. The results indicate that specific stiffener designs play a critical role in tuning band gap properties and enhancing structural vibration performance, offering valuable insights for vibration reduction in fluid-structure coupled curved stiffened plate applications.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104487"},"PeriodicalIF":3.5,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791355","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}
Pub Date : 2025-12-18DOI: 10.1016/j.jfluidstructs.2025.104489
Hao Lv , Tianli Jiang , Wei Chen , Huliang Dai , Lin Wang
Fluid-conveying pipes are widely used across various engineering fields, including aerospace, marine, nuclear and mechanical systems. Establishing a theoretical model that balances high accuracy with computational efficiency is essential for investigating the nonlinear dynamical behavior of such systems. In this study, a new fifth-order Taylor expansion model is proposed to improve the representation of the bending curvature compared to the conventional third-order approximations. By applying the axial inextensibility condition, the kinematic relationship between transverse and axial displacements of the deformed pipe is obtained. Using Hamilton’s principle, the nonlinear governing equation of motion for a cantilevered fluid-conveying pipe is derived within the fifth-order Taylor expansion framework. The resulting partial differential equation is spatially discretized via the Galerkin method and numerically solved using the fourth-order Runge-Kutta algorithm to analyze the nonlinear dynamic responses. Numerical calculations are conducted to compare the computational accuracy and efficiency of the proposed fifth-order Taylor expansion model against both the traditional third-order model and the geometrically exact model. In addition, the influence of two key parameters—mass ratio and gravity parameter—on the dynamical behavior of the pipe is further examined under both high and low flow velocities. Results show that the fifth-order Taylor expansion model offers improved accuracy and wider applicability over the third-order model.
{"title":"A new dynamical model for cantilevered pipe conveying fluid based on fifth-order Taylor expansion","authors":"Hao Lv , Tianli Jiang , Wei Chen , Huliang Dai , Lin Wang","doi":"10.1016/j.jfluidstructs.2025.104489","DOIUrl":"10.1016/j.jfluidstructs.2025.104489","url":null,"abstract":"<div><div>Fluid-conveying pipes are widely used across various engineering fields, including aerospace, marine, nuclear and mechanical systems. Establishing a theoretical model that balances high accuracy with computational efficiency is essential for investigating the nonlinear dynamical behavior of such systems. In this study, a new fifth-order Taylor expansion model is proposed to improve the representation of the bending curvature compared to the conventional third-order approximations. By applying the axial inextensibility condition, the kinematic relationship between transverse and axial displacements of the deformed pipe is obtained. Using Hamilton’s principle, the nonlinear governing equation of motion for a cantilevered fluid-conveying pipe is derived within the fifth-order Taylor expansion framework. The resulting partial differential equation is spatially discretized via the Galerkin method and numerically solved using the fourth-order Runge-Kutta algorithm to analyze the nonlinear dynamic responses. Numerical calculations are conducted to compare the computational accuracy and efficiency of the proposed fifth-order Taylor expansion model against both the traditional third-order model and the geometrically exact model. In addition, the influence of two key parameters—mass ratio and gravity parameter—on the dynamical behavior of the pipe is further examined under both high and low flow velocities. Results show that the fifth-order Taylor expansion model offers improved accuracy and wider applicability over the third-order model.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104489"},"PeriodicalIF":3.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791353","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}
Pub Date : 2025-12-17DOI: 10.1016/j.jfluidstructs.2025.104491
Lixuan Zhao , Qiusheng Li
Despite extensive studies on the aerodynamics and aeroelastic behavior of three-dimensional (3D) square cylinders under turbulent and smooth flows, limited attention has been paid to the effects of large-scale sinusoidal gusts. In particular, the influence of such unsteady inflow conditions on wind-induced vibration characteristics of 3D aeroelastic bluff bodies remains underexplored. This study experimentally investigates the influence of streamwise sinusoidal oscillating flows (SSOFs) on the wind-induced vibrations of a 3D aeroelastic square cylinder, focusing on the instability phenomena of vortex-induced vibration (VIV) and transverse galloping. Wind tunnel testing is conducted to measure the along-wind and across-wind displacement responses under various SSOF conditions, supplemented by wake velocity measurements. To further explore the sound-gust coupling effects on fluid-structure interactions, sinusoidal sound disturbance is also considered. The results reveal that SSOFs significantly enhance along-wind responses while attenuating across-wind vibrations, with the impact depending on gust amplitude and frequency. Vortex shedding in the wake is notably suppressed, especially within the VIV regime. Besides, sound resonant with the cylinder amplifies oscillations and fosters instability, while resonance with the gust tends to suppress them. These findings offer new insights into the aeroelastic responses of bluff bodies in complex unsteady flow environments and highlight the potential influence of sound-flow coupling on structural performance.
{"title":"Aeroelastic response of a three-dimensional square cylinder to large-scale sinusoidal gusts with acoustic disturbances","authors":"Lixuan Zhao , Qiusheng Li","doi":"10.1016/j.jfluidstructs.2025.104491","DOIUrl":"10.1016/j.jfluidstructs.2025.104491","url":null,"abstract":"<div><div>Despite extensive studies on the aerodynamics and aeroelastic behavior of three-dimensional (3D) square cylinders under turbulent and smooth flows, limited attention has been paid to the effects of large-scale sinusoidal gusts. In particular, the influence of such unsteady inflow conditions on wind-induced vibration characteristics of 3D aeroelastic bluff bodies remains underexplored. This study experimentally investigates the influence of streamwise sinusoidal oscillating flows (SSOFs) on the wind-induced vibrations of a 3D aeroelastic square cylinder, focusing on the instability phenomena of vortex-induced vibration (VIV) and transverse galloping. Wind tunnel testing is conducted to measure the along-wind and across-wind displacement responses under various SSOF conditions, supplemented by wake velocity measurements. To further explore the sound-gust coupling effects on fluid-structure interactions, sinusoidal sound disturbance is also considered. The results reveal that SSOFs significantly enhance along-wind responses while attenuating across-wind vibrations, with the impact depending on gust amplitude and frequency. Vortex shedding in the wake is notably suppressed, especially within the VIV regime. Besides, sound resonant with the cylinder amplifies oscillations and fosters instability, while resonance with the gust tends to suppress them. These findings offer new insights into the aeroelastic responses of bluff bodies in complex unsteady flow environments and highlight the potential influence of sound-flow coupling on structural performance.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104491"},"PeriodicalIF":3.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791348","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}
Pub Date : 2025-12-17DOI: 10.1016/j.jfluidstructs.2025.104488
Abhinav Thakurta , Priscilla Williams , Ram Balachandar
This study experimentally investigates the flow around emergent, wall-mounted circular cylinders wrapped in a nine-start bidirectional helical mesh. The motivation stems from the need to reduce local scour in hydraulic and offshore structures, where conventional porous coatings are prone to sediment clogging. The proposed bidirectional mesh acts as a passive flow control method to alter wake dynamics and also potentially enhance heat transfer in pin fin applications. Three mesh configurations with a fixed pitch of 2d and varying heights, 0.01d, 0.02d, and 0.04d (where d is the cylinder diameter), are evaluated. Experiments were conducted at a Reynolds number of 14,500 (based on cylinder diameter), using particle image velocimetry (PIV) to capture detailed velocity fields and analyze flow structures. At lower mesh heights, only minor deviations from the baseline (bare cylinder) flow are observed. However, the 0.04d mesh notably reduces wake mean velocity, elongates the recirculation region, and distorts the near-bed wake structure. Instantaneous velocity fields and probability density function analysis reveal enhanced flapping of the separated shear layers at mid-wake for the 0.04d case. Two-point correlation analysis shows that this configuration increases near-bed coherent structure size, while smaller mesh heights reduce spatial coherence. Upstream of the cylinder, the flow exhibits bimodal unsteadiness, marked by intermittent transitions between back-flow and zero-flow modes, indicating that the horseshoe vortex system is sensitive to mesh height. Reynolds stress distributions at the cylinder-bed junction further highlight that the 0.04d mesh represents a threshold, beyond which significant changes in both upstream junction flow and downstream wake behaviour become apparent.
{"title":"Flow dynamics around mesh wrapped wall-mounted circular cylinders","authors":"Abhinav Thakurta , Priscilla Williams , Ram Balachandar","doi":"10.1016/j.jfluidstructs.2025.104488","DOIUrl":"10.1016/j.jfluidstructs.2025.104488","url":null,"abstract":"<div><div>This study experimentally investigates the flow around emergent, wall-mounted circular cylinders wrapped in a nine-start bidirectional helical mesh. The motivation stems from the need to reduce local scour in hydraulic and offshore structures, where conventional porous coatings are prone to sediment clogging. The proposed bidirectional mesh acts as a passive flow control method to alter wake dynamics and also potentially enhance heat transfer in pin fin applications. Three mesh configurations with a fixed pitch of 2<em>d</em> and varying heights, 0.01<em>d</em>, 0.02<em>d</em>, and 0.04<em>d</em> (where <em>d</em> is the cylinder diameter), are evaluated. Experiments were conducted at a Reynolds number of 14,500 (based on cylinder diameter), using particle image velocimetry (PIV) to capture detailed velocity fields and analyze flow structures. At lower mesh heights, only minor deviations from the baseline (bare cylinder) flow are observed. However, the 0.04<em>d</em> mesh notably reduces wake mean velocity, elongates the recirculation region, and distorts the near-bed wake structure. Instantaneous velocity fields and probability density function analysis reveal enhanced flapping of the separated shear layers at mid-wake for the 0.04<em>d</em> case. Two-point correlation analysis shows that this configuration increases near-bed coherent structure size, while smaller mesh heights reduce spatial coherence. Upstream of the cylinder, the flow exhibits bimodal unsteadiness, marked by intermittent transitions between back-flow and zero-flow modes, indicating that the horseshoe vortex system is sensitive to mesh height. Reynolds stress distributions at the cylinder-bed junction further highlight that the 0.04<em>d</em> mesh represents a threshold, beyond which significant changes in both upstream junction flow and downstream wake behaviour become apparent.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104488"},"PeriodicalIF":3.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791349","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}
Pub Date : 2025-12-16DOI: 10.1016/j.jfluidstructs.2025.104485
Jingbo Qing , Jiabin Liu , Jialei Yan , Colin Whittaker , Anxin Guo
This study proposes a novel method for identifying wave load on floating structures using monitored in-situ wave elevation and structural motion data. Based on potential flow theory, this method establishes transfer matrices linking structural surface pressure to measurable wave elevations and structural motion. The derivation of the transfer matrices relies on truncated cylindrical harmonic expansion, Green’s function integral equation and panel-based discretization. By precomputing the transfer matrices, the approach achieves real-time hydrodynamic force estimation using only monitoring data, circumventing full-domain velocity potential solutions. The proposed method was validated through experiments conducted in a large-scale flume, demonstrating its accuracy and reliability. Phase space reconstruction reveals that the identified results preserve key dynamical characteristics of the system. Parameter analyses confirm its robustness against variations in discretization and truncation. The study also examines the influence of wave spectral truncation and measurement point layout, providing practical guidelines for parameter selection. This approach offers the advantage of easily obtainable monitoring data, overcoming traditional sensor deployment limitations while providing a scalable solution for real-time wave load monitoring of floating structures.
{"title":"Wave load identification for a floating cylinder using in-situ wave elevation and structural motion data","authors":"Jingbo Qing , Jiabin Liu , Jialei Yan , Colin Whittaker , Anxin Guo","doi":"10.1016/j.jfluidstructs.2025.104485","DOIUrl":"10.1016/j.jfluidstructs.2025.104485","url":null,"abstract":"<div><div>This study proposes a novel method for identifying wave load on floating structures using monitored in-situ wave elevation and structural motion data. Based on potential flow theory, this method establishes transfer matrices linking structural surface pressure to measurable wave elevations and structural motion. The derivation of the transfer matrices relies on truncated cylindrical harmonic expansion, Green’s function integral equation and panel-based discretization. By precomputing the transfer matrices, the approach achieves real-time hydrodynamic force estimation using only monitoring data, circumventing full-domain velocity potential solutions. The proposed method was validated through experiments conducted in a large-scale flume, demonstrating its accuracy and reliability. Phase space reconstruction reveals that the identified results preserve key dynamical characteristics of the system. Parameter analyses confirm its robustness against variations in discretization and truncation. The study also examines the influence of wave spectral truncation and measurement point layout, providing practical guidelines for parameter selection. This approach offers the advantage of easily obtainable monitoring data, overcoming traditional sensor deployment limitations while providing a scalable solution for real-time wave load monitoring of floating structures.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104485"},"PeriodicalIF":3.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791354","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}
Pub Date : 2025-12-11DOI: 10.1016/j.jfluidstructs.2025.104486
Si Peng , Md. Mahbub Alam , Yu Zhou
The fluid-structure interaction (FSI) of a flexible wing with two ends fixed-supported is experimentally investigated. The nominal angle α0 of attack examined is varied from 0° to 90°, with the chord-based Reynolds number Rec = 3.0 × 104 - 1.8 × 105, corresponding to reduced velocities Ur = 12 - 70. Various techniques are deployed to capture simultaneously the flow field and fluid forces on the wing, along with the bending and torsional displacements. Careful analysis of experimental data reveals three distinct flow regimes, i.e., the small (I, α0 = 0°–8°) and large (III, α0 > 12°) angle of attack regimes and a transitional regime II (8° < α0 ≤ 12°), based on fluid forces, structural vibrations and flow structures. In regime I, the torsional deformation alters the local effective angle of attack, leading to early stall onset. It is surprisingly found that the bending vibration is strongly coupled with a significant torsional displacement in regime I, resulting in the sequential occurrence of three distinct fluid-structure couplings, i.e. the classical, light- and deep-stall flutters, with increasing α0. These couplings result in an increase and a decrease in the bending and torsional vibration frequencies of the flexible wing, respectively, which are distinctly different from their counterpart of spring-supported rigid wings. This difference accounts for the great disparity between the FSIs of the two types of wings in terms of the frequencies, damping ratios and vibration amplitude of the fluid-structure system, along with the surrounding flow structure. A model is developed to predict the variation in the frequency of the bending vibration, which the conventional beam theory fails to predict.
{"title":"Fluid-structure interaction of a fixed-fixed high-aspect-ratio flexible wing in crossflow","authors":"Si Peng , Md. Mahbub Alam , Yu Zhou","doi":"10.1016/j.jfluidstructs.2025.104486","DOIUrl":"10.1016/j.jfluidstructs.2025.104486","url":null,"abstract":"<div><div>The fluid-structure interaction (FSI) of a flexible wing with two ends fixed-supported is experimentally investigated. The nominal angle <em>α</em><sub>0</sub> of attack examined is varied from 0° to 90°, with the chord-based Reynolds number <em>Re<sub>c</sub></em> = 3.0 × 10<sup>4</sup> - 1.8 × 10<sup>5</sup>, corresponding to reduced velocities <em>U</em><sub>r</sub> = 12 - 70. Various techniques are deployed to capture simultaneously the flow field and fluid forces on the wing, along with the bending and torsional displacements. Careful analysis of experimental data reveals three distinct flow regimes, i.e., the small (I, <em>α</em><sub>0</sub> = 0°–8°) and large (III, <em>α</em><sub>0</sub> > 12°) angle of attack regimes and a transitional regime II (8° < <em>α</em><sub>0</sub> ≤ 12°), based on fluid forces, structural vibrations and flow structures. In regime I, the torsional deformation alters the local effective angle of attack, leading to early stall onset. It is surprisingly found that the bending vibration is strongly coupled with a significant torsional displacement in regime I, resulting in the sequential occurrence of three distinct fluid-structure couplings, i.e. the classical, light- and deep-stall flutters, with increasing <em>α</em><sub>0</sub>. These couplings result in an increase and a decrease in the bending and torsional vibration frequencies of the flexible wing, respectively, which are distinctly different from their counterpart of spring-supported rigid wings. This difference accounts for the great disparity between the FSIs of the two types of wings in terms of the frequencies, damping ratios and vibration amplitude of the fluid-structure system, along with the surrounding flow structure. A model is developed to predict the variation in the frequency of the bending vibration, which the conventional beam theory fails to predict.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104486"},"PeriodicalIF":3.5,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145738561","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}
Pub Date : 2025-12-06DOI: 10.1016/j.jfluidstructs.2025.104477
Maud Kocher , Pierre Moussou , Aurélien Joly , Sofiane Benhamadouche , Vincent Stobiac , Romain Lagrange , Domenico Panunzio , Philippe Piteau
Pressure vessels submitted to turbulent flows are prone to fluid-structure interactions and vibrations. The design of a nuclear power plant comes along with the prediction of the large scale vibration pattern generated by turbulent flows exerted upon large areas of the core barrel containing the fuel assemblies.
The present paper focuses on turbulent forcing in annular gaps with impinging inlets, in view of assessing the relevance of traditional models of reactor vessel studies and of improving future calculations. An analytical reference case is designed to test the pressure field homogeneity hypothesis of the literature models. Pressure fluctuations associated to the turbulent flow are measured in an experimental mock-up and calculated in CFD simulations, at a gap Reynolds number of 105. The global flow pattern in the annular gap is first provided. The Power Spectrum Density of the pressure field and its convection and coherence parameters are obtained both experimentally and numerically. A fair agreement is found between the measurements and the simulations, and the flow pattern appears inhomogenous in large proportions, contrary to the traditional representation. Furthermore, the first mode of vibration of the inner cylinder is measured under turbulent forcing, and compared to the predictions of the simplified model and of CFD calculations: a fair agreement is observed. Finally, the literature model is revisited in the light of these findings, and some potential improvements are discussed.
{"title":"Turbulence-induced vibration of coaxial cylinders with impinging inlets","authors":"Maud Kocher , Pierre Moussou , Aurélien Joly , Sofiane Benhamadouche , Vincent Stobiac , Romain Lagrange , Domenico Panunzio , Philippe Piteau","doi":"10.1016/j.jfluidstructs.2025.104477","DOIUrl":"10.1016/j.jfluidstructs.2025.104477","url":null,"abstract":"<div><div>Pressure vessels submitted to turbulent flows are prone to fluid-structure interactions and vibrations. The design of a nuclear power plant comes along with the prediction of the large scale vibration pattern generated by turbulent flows exerted upon large areas of the core barrel containing the fuel assemblies.</div><div>The present paper focuses on turbulent forcing in annular gaps with impinging inlets, in view of assessing the relevance of traditional models of reactor vessel studies and of improving future calculations. An analytical reference case is designed to test the pressure field homogeneity hypothesis of the literature models. Pressure fluctuations associated to the turbulent flow are measured in an experimental mock-up and calculated in CFD simulations, at a gap Reynolds number of 10<sup>5</sup>. The global flow pattern in the annular gap is first provided. The Power Spectrum Density of the pressure field and its convection and coherence parameters are obtained both experimentally and numerically. A fair agreement is found between the measurements and the simulations, and the flow pattern appears inhomogenous in large proportions, contrary to the traditional representation. Furthermore, the first mode of vibration of the inner cylinder is measured under turbulent forcing, and compared to the predictions of the simplified model and of CFD calculations: a fair agreement is observed. Finally, the literature model is revisited in the light of these findings, and some potential improvements are discussed.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"141 ","pages":"Article 104477"},"PeriodicalIF":3.5,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685728","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}
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