Pub Date : 2025-10-23DOI: 10.1016/j.jfluidstructs.2025.104444
D.A. Pulido-Caviedes , J.A. Licea-Salazar , A. Cros
We study the stability of a rectangular, flexible plate subject to twisting motions and immersed in a uniform, incompresible axial flow. The twisting motion is characterized by the angle where is the axial coordinate and is time, in such a way that no spanwise curvature is allowed. The complex fluid–structure interaction is governed by the torque which comes from the pressure difference between both faces of the plate. By writting the boundary conditions in the Fourier space, the three-dimensional flow potential generated by the twisting flexible plate is calculated and the torque is estimated. Subsequently, the Galerkin method enables the estimation of the frequency and growth rate of each plate mode as a function of three nondimensional parameters: a reduced fluid velocity, the mass ratio between the fluid and plate densities, and the aspect ratio of the plate. Three different boundary conditions are analyzed: clamped-free, clamped-clamped and free-free. We find that, in all three cases, mode 1 first destabilizes through divergence when the fluid velocity is increased. At higher speed values, fluttering develops as a combination of the first two modes in both the free-free and clamped-clamped configurations. Our findings also suggest that greater plate mass and reduced width contribute to improved plate stability and for a given aspect ratio, the critical velocities evolve as .
{"title":"Stability analysis of a twisting flexible plate immersed in an axial airflow","authors":"D.A. Pulido-Caviedes , J.A. Licea-Salazar , A. Cros","doi":"10.1016/j.jfluidstructs.2025.104444","DOIUrl":"10.1016/j.jfluidstructs.2025.104444","url":null,"abstract":"<div><div>We study the stability of a rectangular, flexible plate subject to twisting motions and immersed in a uniform, incompresible axial flow. The twisting motion is characterized by the angle <span><math><mrow><mi>ϕ</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>t</mi><mo>)</mo></mrow></mrow></math></span> where <span><math><mi>x</mi></math></span> is the axial coordinate and <span><math><mi>t</mi></math></span> is time, in such a way that no spanwise curvature is allowed. The complex fluid–structure interaction is governed by the torque which comes from the pressure difference between both faces of the plate. By writting the boundary conditions in the Fourier space, the three-dimensional flow potential generated by the twisting flexible plate is calculated and the torque is estimated. Subsequently, the Galerkin method enables the estimation of the frequency and growth rate of each plate mode as a function of three nondimensional parameters: a reduced fluid velocity, the mass ratio <span><math><mi>M</mi></math></span> between the fluid and plate densities, and the aspect ratio of the plate. Three different boundary conditions are analyzed: clamped-free, clamped-clamped and free-free. We find that, in all three cases, mode 1 first destabilizes through divergence when the fluid velocity is increased. At higher speed values, fluttering develops as a combination of the first two modes in both the free-free and clamped-clamped configurations. Our findings also suggest that greater plate mass and reduced width contribute to improved plate stability and for a given aspect ratio, the critical velocities evolve as <span><math><mrow><mn>1</mn><mo>/</mo><msqrt><mrow><mi>M</mi></mrow></msqrt></mrow></math></span>.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"140 ","pages":"Article 104444"},"PeriodicalIF":3.5,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340657","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 : 2025-10-23DOI: 10.1016/j.jfluidstructs.2025.104443
Jiayun Zhang , Yongshun Zeng , Peijian Zhou , Wei Wang , Lingjiu Zhou , Zhifeng Yao
This paper investigates the modal characteristics of an underwater disc at different rotation speeds through modal testing. Modal testing was performed on the underwater disc within a rotation speed range of 0 to 720 rpm using a specially designed experimental setup. Modal analysis was conducted to extract the natural frequencies, damping ratios, and mode shapes of the disc. The study focuses on the characteristics of Coupled Nodal Circle and Diameter (CNCD) modes related to rotation speeds. The results show that: (1) the mode shapes and natural frequencies of the non-rotating underwater disc are consistent with the analytical predictions; (2) experiments show that CNCD mode frequencies agree with the analytical model’s forward-wave predictions, exhibit no splitting due to weak Coriolis force and circulatory forces effects, and that backward waves are overdamped due to higher shear; (3) for RC〈 0.43, CNCD mode damping ratios remain stable under hydrostatic viscous damping. When RC〉 0.43, the (2,1) mode exhibits a significant damping increase, indicating dominance of dynamic hydroelastic damping; (4) resonance was amplified when CNCD modes overlapped with nodal diameter modes, and these speeds should be avoided in engineering practice. The findings provide insights for the design of impellers in high-head pump turbines and the operational performance of such units.
{"title":"Experimental study on modal characteristics of an underwater rotating disc in coupled nodal circle and diameter modes","authors":"Jiayun Zhang , Yongshun Zeng , Peijian Zhou , Wei Wang , Lingjiu Zhou , Zhifeng Yao","doi":"10.1016/j.jfluidstructs.2025.104443","DOIUrl":"10.1016/j.jfluidstructs.2025.104443","url":null,"abstract":"<div><div>This paper investigates the modal characteristics of an underwater disc at different rotation speeds through modal testing. Modal testing was performed on the underwater disc within a rotation speed range of 0 to 720 rpm using a specially designed experimental setup. Modal analysis was conducted to extract the natural frequencies, damping ratios, and mode shapes of the disc. The study focuses on the characteristics of Coupled Nodal Circle and Diameter (CNCD) modes related to rotation speeds. The results show that: (1) the mode shapes and natural frequencies of the non-rotating underwater disc are consistent with the analytical predictions; (2) experiments show that CNCD mode frequencies agree with the analytical model’s forward-wave predictions, exhibit no splitting due to weak Coriolis force and circulatory forces effects, and that backward waves are overdamped due to higher shear; (3) for <em>RC</em>〈 0.43, CNCD mode damping ratios remain stable under hydrostatic viscous damping. When <em>RC</em>〉 0.43, the (2,1) mode exhibits a significant damping increase, indicating dominance of dynamic hydroelastic damping; (4) resonance was amplified when CNCD modes overlapped with nodal diameter modes, and these speeds should be avoided in engineering practice. The findings provide insights for the design of impellers in high-head pump turbines and the operational performance of such units.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"140 ","pages":"Article 104443"},"PeriodicalIF":3.5,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340658","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 : 2025-10-22DOI: 10.1016/j.jfluidstructs.2025.104442
Arthur Haudeville , Xavier Amandolese , Boris Lossouarn , Christophe Giraud-Audine , Olivier Thomas
The present work investigates the ability of a reduced-order fluid–structure model to estimate the vortex-induced vibrations (VIV) of marine lifting surface under hydrodynamic flow, such as hydrofoils. A particular VIV area is scrutinized, for which a hydrodynamic excitation mechanism due to a Kármán-type vortex wake organization successively locks the first twisting and second bending mode of a cantilever truncated hydrofoil. Coupling two structural oscillators with a Van der Pol wake oscillator satisfactorily reproduces the amplitude response and the lock-in frequency. This work also investigates the ability of a piezo-elasto-hydrodynamic model to anticipate the vibration amplitude of the hydrofoil when mitigated thanks to a resonant piezoelectric shunt. Composed of an inductance in series with a resistance connected to a piezoelectric patch, the passive shunt was tuned to minimize the vibration amplitude in the frequency lock-in range. The proposed semi-empirical models are fitted to experimental results in order to reproduce the coupled system’s dynamic.
{"title":"Low-order coupled model for vortex-induced vibrations mitigation by resonant piezoelectric shunt","authors":"Arthur Haudeville , Xavier Amandolese , Boris Lossouarn , Christophe Giraud-Audine , Olivier Thomas","doi":"10.1016/j.jfluidstructs.2025.104442","DOIUrl":"10.1016/j.jfluidstructs.2025.104442","url":null,"abstract":"<div><div>The present work investigates the ability of a reduced-order fluid–structure model to estimate the vortex-induced vibrations (VIV) of marine lifting surface under hydrodynamic flow, such as hydrofoils. A particular VIV area is scrutinized, for which a hydrodynamic excitation mechanism due to a Kármán-type vortex wake organization successively locks the first twisting and second bending mode of a cantilever truncated hydrofoil. Coupling two structural oscillators with a Van der Pol wake oscillator satisfactorily reproduces the amplitude response and the lock-in frequency. This work also investigates the ability of a piezo-elasto-hydrodynamic model to anticipate the vibration amplitude of the hydrofoil when mitigated thanks to a resonant piezoelectric shunt. Composed of an inductance in series with a resistance connected to a piezoelectric patch, the passive shunt was tuned to minimize the vibration amplitude in the frequency lock-in range. The proposed semi-empirical models are fitted to experimental results in order to reproduce the coupled system’s dynamic.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104442"},"PeriodicalIF":3.5,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363700","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 : 2025-10-22DOI: 10.1016/j.jfluidstructs.2025.104438
Jiawei Shen , Shixiao Fu , Xuepeng Fu , Torgeir Moan , Svein Sævik
Flow-induced vibration (FIV) commonly occurs in rigidly coupled twin-pipe structures. However, the limited understanding of their FIV responses and hydrodynamic features presents a major challenge to the development of reliable engineering designs. To bridge this gap, the present study experimentally investigates the FIV characteristics of a rigidly coupled twin-pipe model with elastic support using a virtual physical framework (VPF), which enables flexible control of structural parameters during physical testing. A distinctive feature of twin-pipe structures is the presence of in-line hydrodynamic interactions and torsional moments arising from the rigid coupling. The in-line interaction is primarily compressive and becomes more pronounced as the mass ratio increases. The torsional moment coefficient exhibits a rise–fall trend with increasing reduced velocity and stabilizes around 0.46 at low mass ratios. In addition, an “amplitude drop” phenomenon is observed near , attributed to energy dissipation from the downstream pipe. The mass ratio significantly affects FIV amplitude, frequency, and hydrodynamic coefficients. As the mass ratio decreases, the synchronization region broadens and the hydrodynamic coefficients become more stable. Meanwhile, at mass ratio of 1.0, a “resonance forever” behavior is observed. Damping primarily suppresses FIV amplitude, with minimal impact on dominant frequency and hydrodynamic coefficients. These findings provide valuable insights into twin-pipe FIV mechanisms and support a scientific basis for future structural design optimization.
{"title":"Flow-induced vibration of twin-pipe model with varying mass and damping: A study using virtual physical framework","authors":"Jiawei Shen , Shixiao Fu , Xuepeng Fu , Torgeir Moan , Svein Sævik","doi":"10.1016/j.jfluidstructs.2025.104438","DOIUrl":"10.1016/j.jfluidstructs.2025.104438","url":null,"abstract":"<div><div>Flow-induced vibration (FIV) commonly occurs in rigidly coupled twin-pipe structures. However, the limited understanding of their FIV responses and hydrodynamic features presents a major challenge to the development of reliable engineering designs. To bridge this gap, the present study experimentally investigates the FIV characteristics of a rigidly coupled twin-pipe model with elastic support using a virtual physical framework (VPF), which enables flexible control of structural parameters during physical testing. A distinctive feature of twin-pipe structures is the presence of in-line hydrodynamic interactions and torsional moments arising from the rigid coupling. The in-line interaction is primarily compressive and becomes more pronounced as the mass ratio increases. The torsional moment coefficient exhibits a rise–fall trend with increasing reduced velocity <span><math><msub><mrow><mi>U</mi></mrow><mrow><mi>R</mi></mrow></msub></math></span> and stabilizes around 0.46 at low mass ratios. In addition, an “amplitude drop” phenomenon is observed near <span><math><mrow><msub><mrow><mi>U</mi></mrow><mrow><mi>R</mi></mrow></msub><mo>=</mo><mn>6</mn></mrow></math></span>, attributed to energy dissipation from the downstream pipe. The mass ratio significantly affects FIV amplitude, frequency, and hydrodynamic coefficients. As the mass ratio decreases, the synchronization region broadens and the hydrodynamic coefficients become more stable. Meanwhile, at mass ratio of 1.0, a “resonance forever” behavior is observed. Damping primarily suppresses FIV amplitude, with minimal impact on dominant frequency and hydrodynamic coefficients. These findings provide valuable insights into twin-pipe FIV mechanisms and support a scientific basis for future structural design optimization.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104438"},"PeriodicalIF":3.5,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363699","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 : 2025-10-18DOI: 10.1016/j.jfluidstructs.2025.104440
Wenlong Luo , Bo Huang , Lihua Wang , Jing Chen , Hongbo Su , Jianting Zhou , Hao Ding , Ke Li , Liang Cheng , Dan Zhong
The submerged floating tunnel (SFT) is a new type of transportation structure used to cross water areas. In complex marine environments, the long-span SFT is subjected to nonlinear coupled effects of multiple loads, resulting in extremely complex dynamic responses. At present, the calculation methods for the dynamic response of the long-span SFT in marine environments have the following main deficiencies: (1) When different cable models, tube-end boundary conditions, and load patterns are adopted, the resulting mathematical models of the SFT often exhibit different expressions, with complex governing equations. The models lack flexibility and generality when considering different cable arrangements and load combinations. Existing studies are typically limited to fixed structural configurations under single-load effects. (2) Restricted by computational costs, the Morison equation is commonly used to calculate fluid loads on long-span SFTs. This equation can only account for one-way fluid-structure interaction (FSI) effects, fails to compute the torque exerted by fluids on the SFT tube, and ignores the influence of seabed topography on the flow field. Addressing the current research gaps in the analysis of dynamic characteristics of the long-span SFT under marine conditions, particularly the challenges in two-way FSI computation for long-span configurations, this paper proposes a time-domain computational method for dynamic response analysis of the long-span SFT under coupled action of multiple loads, which provides a general computational framework for dealing with the multi-load action problems of SFTs. The computational framework incorporates a two-way FSI calculation model based on a system of two-dimensional potential flow wave flumes, which overcomes the limitations in computational efficiency in bidirectional coupling analysis of the long-span SFT, and addresses the challenges in the applicability of the Morison equation under complex working conditions. This paper verifies the correctness of the proposed method for calculating structural dynamic responses by comparing the calculation results of finite element mode. The accuracy of the potential flow flume in calculating wave loads is also verified by comparing with the calculation results of the viscous fluid model. Finally, by comparing with the results of the frequency-domain calculation of dynamic responses of the SFT, it demonstrates the reliability of the FSI calculation.
{"title":"A time-domain computational method for the assessment of the dynamic response of long-span submerged floating tunnels under coupled action of multiple loads in marine environments","authors":"Wenlong Luo , Bo Huang , Lihua Wang , Jing Chen , Hongbo Su , Jianting Zhou , Hao Ding , Ke Li , Liang Cheng , Dan Zhong","doi":"10.1016/j.jfluidstructs.2025.104440","DOIUrl":"10.1016/j.jfluidstructs.2025.104440","url":null,"abstract":"<div><div>The submerged floating tunnel (SFT) is a new type of transportation structure used to cross water areas. In complex marine environments, the long-span SFT is subjected to nonlinear coupled effects of multiple loads, resulting in extremely complex dynamic responses. At present, the calculation methods for the dynamic response of the long-span SFT in marine environments have the following main deficiencies: (1) When different cable models, tube-end boundary conditions, and load patterns are adopted, the resulting mathematical models of the SFT often exhibit different expressions, with complex governing equations. The models lack flexibility and generality when considering different cable arrangements and load combinations. Existing studies are typically limited to fixed structural configurations under single-load effects. (2) Restricted by computational costs, the Morison equation is commonly used to calculate fluid loads on long-span SFTs. This equation can only account for one-way fluid-structure interaction (FSI) effects, fails to compute the torque exerted by fluids on the SFT tube, and ignores the influence of seabed topography on the flow field. Addressing the current research gaps in the analysis of dynamic characteristics of the long-span SFT under marine conditions, particularly the challenges in two-way FSI computation for long-span configurations, this paper proposes a time-domain computational method for dynamic response analysis of the long-span SFT under coupled action of multiple loads, which provides a general computational framework for dealing with the multi-load action problems of SFTs. The computational framework incorporates a two-way FSI calculation model based on a system of two-dimensional potential flow wave flumes, which overcomes the limitations in computational efficiency in bidirectional coupling analysis of the long-span SFT, and addresses the challenges in the applicability of the Morison equation under complex working conditions. This paper verifies the correctness of the proposed method for calculating structural dynamic responses by comparing the calculation results of finite element mode. The accuracy of the potential flow flume in calculating wave loads is also verified by comparing with the calculation results of the viscous fluid model. Finally, by comparing with the results of the frequency-domain calculation of dynamic responses of the SFT, it demonstrates the reliability of the FSI calculation.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104440"},"PeriodicalIF":3.5,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321275","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 : 2025-10-18DOI: 10.1016/j.jfluidstructs.2025.104441
Huan-Wen Liu
The differential equations governing water surface gravity wave motion over uneven seabeds are generally difficult to be solved analytically. For the original Laplace equation together with appropriate boundary and radiation conditions, there appears to be only one closed-form solution, called Roseau’s solution. For the depth-averaged equations such as the mild-slope type equation, the Ye equation, and the Boussinesq equation, the closed-form solutions are rare because the wavenumber has never been solved exactly from the Airy dispersion equation since it was derived by Airy in 1841. In this paper, Airy dispersion equation is exactly solved for linear surface gravity waves propagating over a cluster of special terrains, called the L-type seabeds. Furthermore, based on the explicit Airy wavenumbers, closed-form solutions to the Ye equation for wave reflection by a trapezoidal hump/trench with the two slopes being the L-type terrains are successfully constructed. To this author’s knowledge, this is the first group of closed-form solutions to depth-averaged wave equations in the whole wave range from shallow-water waves to deep-water waves.
{"title":"Exact and explicit wavenumbers and closed-form solutions of the Ye equation for water wave propagation over L-type bed terrains","authors":"Huan-Wen Liu","doi":"10.1016/j.jfluidstructs.2025.104441","DOIUrl":"10.1016/j.jfluidstructs.2025.104441","url":null,"abstract":"<div><div>The differential equations governing water surface gravity wave motion over uneven seabeds are generally difficult to be solved analytically. For the original Laplace equation together with appropriate boundary and radiation conditions, there appears to be only one closed-form solution, called Roseau’s solution. For the depth-averaged equations such as the mild-slope type equation, the Ye equation, and the Boussinesq equation, the closed-form solutions are rare because the wavenumber has never been solved exactly from the Airy dispersion equation since it was derived by Airy in 1841. In this paper, Airy dispersion equation is exactly solved for linear surface gravity waves propagating over a cluster of special terrains, called the L-type seabeds. Furthermore, based on the explicit Airy wavenumbers, closed-form solutions to the Ye equation for wave reflection by a trapezoidal hump/trench with the two slopes being the L-type terrains are successfully constructed. To this author’s knowledge, this is the first group of closed-form solutions to depth-averaged wave equations in the whole wave range from shallow-water waves to deep-water waves.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104441"},"PeriodicalIF":3.5,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321276","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 : 2025-10-17DOI: 10.1016/j.jfluidstructs.2025.104437
Wenyu Chen , Con Doolan , Danielle Moreau
A finite-length circular cylinder mounted to a wall serves as a simplified model for bluff bodies encountering flow, with a wide range of relevant applications, including aircraft landing gear, automobile appendages, and wind turbine masts. In the present study, finite wall-mounted circular cylinders with different spanwise aspect ratios ( where is the length of the cylinder and is its diameter) of 3.2, 6.5, 12.9 and 22.6 are examined at a Reynolds number of based on the cylinder diameter. The incoming boundary layer thickness on the wall to which the cylinder is mounted is . Large Eddy Simulation (LES) is employed to simulate the turbulent flow, and the Ffowcs Williams–Hawkings equations are solved simultaneously to predict the far-field noise. The acoustic spectrum of the circular FWMCs is characterized by tonal peaks for aspect ratios = 3.2, 12.9, and 22.6 in which a primary tonal peak (P1) and lower frequency secondary peak (P2) are identified. The transition from dipole to quadrupole in the three-dimensional time-averaged vortical structures is also summarized. Notably, suppression of vortex shedding is observed for the cylinder with , while cellular vortex shedding is observed in longer cylinders. The shedding cells near the junction and free tip exhibit lower shedding frequencies compared to the mid-span cell. Wake structures in-phase to the acoustic pressure are examined, confirming both the tip and mid-span related vortex shedding noise of the circular FWMCs. Furthermore, the in-phase structures associated with the primary (P1) peak are characterized by vertical vortex tubes that are well-organized downstream and exhibit strong consistency with Kármán vortex tubes shedding from the mid-span. The coherent structures corresponding to the secondary (P2) peak are found to be concentrated to the free end and are inclined in the downstream direction.
固定在壁上的有限长圆柱体是钝体遇到气流的简化模型，在飞机起落架、汽车附件、风力涡轮机桅杆等领域有着广泛的应用。在本研究中，在雷诺数Re=12,000的条件下，基于圆柱体直径，研究了不同展向纵横比（AR=L/D，其中L为圆柱体长度，D为圆柱体直径）分别为3.2、6.5、12.9和22.6的有限壁挂圆柱体。圆柱体所处壁面的来面层厚度为δ/D=0.83。采用大涡模拟（Large Eddy Simulation， LES）方法模拟紊流，同时求解Ffowcs williams - hawkins方程来预测远场噪声。在宽高比为AR = 3.2、12.9和22.6时，圆形fwmc的声谱特征为一个主音峰（P1）和一个低频次峰（P2）。总结了三维时均涡结构中偶极子向四极子的转变过程。值得注意的是，在AR=6.5的圆柱体中观察到涡脱落的抑制，而在更长的圆柱体中观察到细胞涡脱落。与跨中单元相比，靠近结和自由尖端的脱落单元表现出较低的脱落频率。研究了与声压相一致的尾迹结构，证实了圆形fwmc的尖端和跨中相关的涡脱落噪声。此外，与初级峰（P1）相关的同相结构以垂直涡管为特征，这些垂直涡管在下游组织良好，与Kármán涡管从跨中脱落具有很强的一致性。次级（P2）峰对应的相干结构集中在自由端，并向下游倾斜。
{"title":"Flow-induced noise of circular finite wall-mounted cylinders","authors":"Wenyu Chen , Con Doolan , Danielle Moreau","doi":"10.1016/j.jfluidstructs.2025.104437","DOIUrl":"10.1016/j.jfluidstructs.2025.104437","url":null,"abstract":"<div><div>A finite-length circular cylinder mounted to a wall serves as a simplified model for bluff bodies encountering flow, with a wide range of relevant applications, including aircraft landing gear, automobile appendages, and wind turbine masts. In the present study, finite wall-mounted circular cylinders with different spanwise aspect ratios (<span><math><mrow><mi>A</mi><mi>R</mi><mo>=</mo><mi>L</mi><mo>/</mo><mi>D</mi></mrow></math></span> where <span><math><mi>L</mi></math></span> is the length of the cylinder and <span><math><mi>D</mi></math></span> is its diameter) of 3.2, 6.5, 12.9 and 22.6 are examined at a Reynolds number of <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>12</mn><mo>,</mo><mn>000</mn></mrow></math></span> based on the cylinder diameter. The incoming boundary layer thickness on the wall to which the cylinder is mounted is <span><math><mrow><mi>δ</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>83</mn></mrow></math></span>. Large Eddy Simulation (LES) is employed to simulate the turbulent flow, and the Ffowcs Williams–Hawkings equations are solved simultaneously to predict the far-field noise. The acoustic spectrum of the circular FWMCs is characterized by tonal peaks for aspect ratios <span><math><mrow><mi>A</mi><mi>R</mi></mrow></math></span> = 3.2, 12.9, and 22.6 in which a primary tonal peak (P1) and lower frequency secondary peak (P2) are identified. The transition from dipole to quadrupole in the three-dimensional time-averaged vortical structures is also summarized. Notably, suppression of vortex shedding is observed for the cylinder with <span><math><mrow><mi>A</mi><mi>R</mi><mo>=</mo><mn>6</mn><mo>.</mo><mn>5</mn></mrow></math></span>, while cellular vortex shedding is observed in longer cylinders. The shedding cells near the junction and free tip exhibit lower shedding frequencies compared to the mid-span cell. Wake structures in-phase to the acoustic pressure are examined, confirming both the tip and mid-span related vortex shedding noise of the circular FWMCs. Furthermore, the in-phase structures associated with the primary (P1) peak are characterized by vertical vortex tubes that are well-organized downstream and exhibit strong consistency with Kármán vortex tubes shedding from the mid-span. The coherent structures corresponding to the secondary (P2) peak are found to be concentrated to the free end and are inclined in the downstream direction.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104437"},"PeriodicalIF":3.5,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321322","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 : 2025-10-08DOI: 10.1016/j.jfluidstructs.2025.104427
Yifan Zhang , Xiantao Zhang , Hanyu Liu , Dengfeng Fu , Zhenguo Gao
Membrane-based floating photovoltaic (M-FPV) platforms represent an innovative approach to offshore floating photovoltaic systems, characterized by a circular floater and a thin membrane. This research introduces a fully coupled time-domain simulation method to analyze the hydroelastic response of the main structure of these platforms under regular and irregular wave conditions. Modal superposition is employed to assess both in-plane and out-of-plane deformations, while the hydrodynamic forces are obtained using linear potential flow theory, incorporating the modified Morison equation for in-plane loads on the floater. Experimental validation was performed using wave tests in a towing tank. The setup included a horizontal mooring system with four lines. Measurements focused on deformations of both the floater and the membrane, along with mooring forces and wave elevations. The numerical results exhibit good agreement with the experimental data. The wave test results demonstrate the complex interaction between platform flexibility and wave behavior. In regular wave tests, the Response Amplitude Operators (RAOs) reveal that platform flexibility allows the structure to better conform to the wave profile at lower frequencies, while higher frequencies are dominated by structural rigidity, highlighting a significant three-dimensional effect. A distinct difference in in-plane deformation between fore and aft parts under the influence of mooring lines was observed. In irregular wave tests, the vertical motion spectrum of the platform aligns with the wave spectrum, showcasing its flexibility. However, the in-plane longitudinal motion spectrum reveals an additional peak at a frequency approximately twice that of the wave spectrum, attributed to the platform’s surge resonance. This study offers a thorough analysis of M-FPV platforms’ hydroelastic response under regular and irregular waves, informing the design and optimization of offshore PV systems.
{"title":"Fully coupled hydroelastic analysis of a membrane-based offshore floating photovoltaic structure: Experimental and numerical studies","authors":"Yifan Zhang , Xiantao Zhang , Hanyu Liu , Dengfeng Fu , Zhenguo Gao","doi":"10.1016/j.jfluidstructs.2025.104427","DOIUrl":"10.1016/j.jfluidstructs.2025.104427","url":null,"abstract":"<div><div>Membrane-based floating photovoltaic (M-FPV) platforms represent an innovative approach to offshore floating photovoltaic systems, characterized by a circular floater and a thin membrane. This research introduces a fully coupled time-domain simulation method to analyze the hydroelastic response of the main structure of these platforms under regular and irregular wave conditions. Modal superposition is employed to assess both in-plane and out-of-plane deformations, while the hydrodynamic forces are obtained using linear potential flow theory, incorporating the modified Morison equation for in-plane loads on the floater. Experimental validation was performed using wave tests in a towing tank. The setup included a horizontal mooring system with four lines. Measurements focused on deformations of both the floater and the membrane, along with mooring forces and wave elevations. The numerical results exhibit good agreement with the experimental data. The wave test results demonstrate the complex interaction between platform flexibility and wave behavior. In regular wave tests, the Response Amplitude Operators (RAOs) reveal that platform flexibility allows the structure to better conform to the wave profile at lower frequencies, while higher frequencies are dominated by structural rigidity, highlighting a significant three-dimensional effect. A distinct difference in in-plane deformation between fore and aft parts under the influence of mooring lines was observed. In irregular wave tests, the vertical motion spectrum of the platform aligns with the wave spectrum, showcasing its flexibility. However, the in-plane longitudinal motion spectrum reveals an additional peak at a frequency approximately twice that of the wave spectrum, attributed to the platform’s surge resonance. This study offers a thorough analysis of M-FPV platforms’ hydroelastic response under regular and irregular waves, informing the design and optimization of offshore PV systems.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104427"},"PeriodicalIF":3.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269135","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 : 2025-10-08DOI: 10.1016/j.jfluidstructs.2025.104436
Zhiwei Liu , Hanfeng Wang , Jiaxuan Li , Ziqiang Zhang , Hui Tang
In order to provide useful guidelines for optimizing piezoelectric energy harvesting designs under near-wall conditions, we experimentally investigate and compare the dynamics and energies of a wall-clamped flexible membrane (FM) in two different cross-flows, i.e., a separated flow induced by a forward-facing step (FFS) and a boundary layer (BL) flow, aiming at revealing the combined effects of the incoming flow and wall contact on flapping dynamics. Four dynamic modes were identified in both the FFS and BL cases by varying flow velocity and FM length: quasi-steady, regular-flapping, tip-contact, and body-contact modes. In the FFS cases, the recirculation zone induced by the step prevents the FM from lodging, whereas in the BL cases, the FM exhibits suppressed amplitudes and near-wall flapping behavior. The evolution of the two contact modes was examined in details, and the variations in contact time and contact distance during the transition between these two modes were quantitatively evaluated. Three-dimensional effects manifest differently in each case, with the FFS showing primarily spanwise bending and the BL case exhibiting pronounced twisting that impacts flapping stability. Energy analysis further reveals that, at high flow velocity, the FM’s kinetic energy dominates over elastic strain energy, with significant energy dissipation occurring during wall contact.
{"title":"Dynamics and energies of a wall-clamped flexible membrane in two different cross-flows","authors":"Zhiwei Liu , Hanfeng Wang , Jiaxuan Li , Ziqiang Zhang , Hui Tang","doi":"10.1016/j.jfluidstructs.2025.104436","DOIUrl":"10.1016/j.jfluidstructs.2025.104436","url":null,"abstract":"<div><div>In order to provide useful guidelines for optimizing piezoelectric energy harvesting designs under near-wall conditions, we experimentally investigate and compare the dynamics and energies of a wall-clamped flexible membrane (FM) in two different cross-flows, i.e., a separated flow induced by a forward-facing step (FFS) and a boundary layer (BL) flow, aiming at revealing the combined effects of the incoming flow and wall contact on flapping dynamics. Four dynamic modes were identified in both the FFS and BL cases by varying flow velocity and FM length: quasi-steady, regular-flapping, tip-contact, and body-contact modes. In the FFS cases, the recirculation zone induced by the step prevents the FM from lodging, whereas in the BL cases, the FM exhibits suppressed amplitudes and near-wall flapping behavior. The evolution of the two contact modes was examined in details, and the variations in contact time and contact distance during the transition between these two modes were quantitatively evaluated. Three-dimensional effects manifest differently in each case, with the FFS showing primarily spanwise bending and the BL case exhibiting pronounced twisting that impacts flapping stability. Energy analysis further reveals that, at high flow velocity, the FM’s kinetic energy dominates over elastic strain energy, with significant energy dissipation occurring during wall contact.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104436"},"PeriodicalIF":3.5,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269134","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 : 2025-10-06DOI: 10.1016/j.jfluidstructs.2025.104434
Yi-Ni Yang , Hao Wang , Ming-Song Zou , Ye Liu , Guo-Cang Sun , Pei Li
Based on three-dimensional sono-elasticity theory, this study proposes an integrated computational method for vibroacoustic coupling analysis of underwater structures equipped with a floating raft and acoustic coatings in finite water depth. The dynamic substructure method decomposes the complex system into three components: the main structure (including main hull, pedestal, bulkheads, and reinforcing ribs), vibration isolators, and the floating raft. Fluid-structure interaction is exclusively considered in the sono-elasticity coupling between the main structure and water, where the governing equations integrate modal superposition method, simple source boundary integral method, and mirror image virtual source method. The floating raft is modeled using the finite element method, its dynamic response is described by the modal superposition method. The isolators' vibration transmission characteristics are characterized using the four-terminal parameter method. Virtual modes are introduced to achieve dynamic coupling integration at connection boundaries. The impedance matrix model is derived to quantify the vibroacoustic transfer mechanism of acoustic coatings. The proposed methodology demonstrates significant advantages in structural optimization and acoustic performance analysis. Regardless of the modification of any component in the system, the overall response can be recalculated by updating the corresponding stiffness matrix, which substantially improves computational efficiency and engineering adaptability. The accuracy and engineering adaptability of the method are validated by numerical case studies and experimental results, and quantitative analyses are conducted on the influence of submergence depth and acoustic coating layout on acoustic radiation. This work provides theoretical foundations and engineering references for coordinated acoustic-stealth optimization of complex underwater structures.
{"title":"An integrated computational method for vibroacoustic coupling analysis of an underwater structure with a floating raft and acoustic coatings","authors":"Yi-Ni Yang , Hao Wang , Ming-Song Zou , Ye Liu , Guo-Cang Sun , Pei Li","doi":"10.1016/j.jfluidstructs.2025.104434","DOIUrl":"10.1016/j.jfluidstructs.2025.104434","url":null,"abstract":"<div><div>Based on three-dimensional sono-elasticity theory, this study proposes an integrated computational method for vibroacoustic coupling analysis of underwater structures equipped with a floating raft and acoustic coatings in finite water depth. The dynamic substructure method decomposes the complex system into three components: the main structure (including main hull, pedestal, bulkheads, and reinforcing ribs), vibration isolators, and the floating raft. Fluid-structure interaction is exclusively considered in the sono-elasticity coupling between the main structure and water, where the governing equations integrate modal superposition method, simple source boundary integral method, and mirror image virtual source method. The floating raft is modeled using the finite element method, its dynamic response is described by the modal superposition method. The isolators' vibration transmission characteristics are characterized using the four-terminal parameter method. Virtual modes are introduced to achieve dynamic coupling integration at connection boundaries. The impedance matrix model is derived to quantify the vibroacoustic transfer mechanism of acoustic coatings. The proposed methodology demonstrates significant advantages in structural optimization and acoustic performance analysis. Regardless of the modification of any component in the system, the overall response can be recalculated by updating the corresponding stiffness matrix, which substantially improves computational efficiency and engineering adaptability. The accuracy and engineering adaptability of the method are validated by numerical case studies and experimental results, and quantitative analyses are conducted on the influence of submergence depth and acoustic coating layout on acoustic radiation. This work provides theoretical foundations and engineering references for coordinated acoustic-stealth optimization of complex underwater structures.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"139 ","pages":"Article 104434"},"PeriodicalIF":3.5,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269132","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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