Journal of Fluids and Structures最新文献

{"title":"Unified meshfree-spectral BEM model for acoustic radiation analysis of double-walled coupled shells","authors":"Xianjie Shi,&nbsp;Xikai Li,&nbsp;Zhou Huang,&nbsp;Qiang Wan","doi":"10.1016/j.jfluidstructs.2025.104279","DOIUrl":"10.1016/j.jfluidstructs.2025.104279","url":null,"abstract":"<div><div>A unified mathematical model for acoustic radiation responses of laminated composite double-walled coupled shells with bulkheads immersed in an unbounded light and heavy fluid environments is established by utilizing unified meshfree-spectral BEM (boundary element method). In order to ensure the stability and reliability of the numerical solution, the mathematical model is divided into several hyperbolic curves, cylindrical shells and ring plates. Different types of the doubly-curved shell are considered such as elliptical and paraboloidal shells. By analyzing the geometrical relationship of double-walled shell, the displacement continuous boundary conditions between adjacent segment interfaces are determined. The structural field and external acoustic field of a double-walled shell are derived by using the energy principle in framework of first-order shear deformation theory and Kirchhoff-Helmholtz integral formulation respectively. The numerical example shows that the mathematical model can be used to solve the acoustic radiation response of the double-walled coupled shell in the acoustic fluid medium. Finally, the effects of representative parameters such as geometry, acoustic fluid medium, boundary conditions and external load on the acoustic radiation characteristics of double-walled shells are systematically discussed, which provides useful information for the design of light and heavy fluid double-walled structures.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104279"},"PeriodicalIF":3.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453699","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":"Stability analysis of an articulated flexible pipe conveying fluid with a rotational spring","authors":"Yikun Wang ,&nbsp;Jianhang Lv ,&nbsp;Mo Yang ,&nbsp;Yang Zhang ,&nbsp;Tao Qin ,&nbsp;Lin Wang","doi":"10.1016/j.jfluidstructs.2025.104277","DOIUrl":"10.1016/j.jfluidstructs.2025.104277","url":null,"abstract":"<div><div>The stability of an articulated flexible pipe conveying fluid by altering its structural parameters is investigated in this paper. Utilizing generalized Hamilton's principle, the governing equations for the motion of both the upper and lower pipe segments of the system are established. The equations are then discretized using the Galerkin's method, which leads to a generalized eigenvalue problem. To validate the mathematical model, the eigenvalue branches of a degenerated system are compared with prior findings by using extreme values for the structural parameters. The results indicate that the instability characteristics of the pipe system are heavily influenced by these parameters. A reduction in the length of the upper segment causes the system to exhibit characteristics similar to either a pinned-free or cantilevered pipe, contingent upon the stiffness of the rotational spring. Secondary flutter phenomena manifest after the third or fourth mode instability as the flow velocity increases. When the upper and lower segments are of equal lengths, the critical flow velocity stabilizes when the spring stiffness surpasses a certain threshold. The inclusion of a flexible joint between the segments increases the system's susceptibility to higher-mode instability. Additionally, an extended upper segment may result in intricate instability behaviors, including a sequence of “instability-restabilization-instability” as the flow velocity rises. These innovative numerical findings provide theoretical perspectives on the dynamic behavior of articulated fluid-conveying pipes.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104277"},"PeriodicalIF":3.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444725","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 data-driven approach for modeling large-amplitude flow-induced oscillations of elastically mounted pitching wings","authors":"Yuanhang Zhu ,&nbsp;Kenneth Breuer","doi":"10.1016/j.jfluidstructs.2025.104282","DOIUrl":"10.1016/j.jfluidstructs.2025.104282","url":null,"abstract":"<div><div>We propose and validate a data-driven approach for modeling large-amplitude flow-induced oscillations of elastically mounted pitching wings. We first train a neural networks regression model for the nonlinear aerodynamic moment using data obtained from experimental measurements during prescribed pitching oscillations and at fixed angles of attack. We then embed this model into an ordinary differential equation solver to solve the governing equation of the passive aeroelastic system with desired structural parameters. The system dynamics predicted by the proposed data-driven approach are characterized and compared with those obtained from physical experiments. The predicted and experimental pitching amplitude, frequency and aerodynamic moment responses are found to be in excellent agreement. Both the inertia-dominated mode and the hydrodynamic-dominated mode are successfully predicted. The transient growth and saturation of the pitching oscillation amplitude and the aerodynamic moment are also faithfully captured by the proposed approach. Additional test cases demonstrate the broad applicability and good scalability potential of this approach.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104282"},"PeriodicalIF":3.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of clamped–clamped elastic panel motion under influence of shock-wave turbulent boundary layer interactions using WMLES with a 3D aeroelastic solver","authors":"Chelsea Johnson ,&nbsp;Luisa Piccolo Serafim ,&nbsp;Joseph C. Oefelein ,&nbsp;Earl H. Dowell","doi":"10.1016/j.jfluidstructs.2025.104281","DOIUrl":"10.1016/j.jfluidstructs.2025.104281","url":null,"abstract":"<div><div>A loosely coupled approach for the prediction of fluid–structure interactions is investigated for a high Reynolds number flow with a shock-wave impinging on a thin flexible panel. The fluid domain is solved using a wall-modeled large eddy simulation (LES), and the resulting time-resolved flowfields are provided as input to a theoretical–computational aeroelastic solver. The computational study mimics the flow and structural conditions of an existing experiment such that the panel displacements can be compared. The approach shows an improvement over an existing theoretical–computational model. For example, predictions of the maximum static deformation, which is a key metric, are shown to be within 10% of the experimental result. Predictions of the time-dependent oscillations of the panel show sensitivity to the coherence length provided to the aeroelastic solver, as noted by Freydin et al. The discrepancy in the magnitude of predicted time-dependent panel oscillations and those observed in the experiment is hypothesized to be due to the lack of instantaneous coupling present in the method, or possibly due to variability in the static pressure of the wind tunnel throughout the run.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"134 ","pages":"Article 104281"},"PeriodicalIF":3.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444766","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":"Comprehensive numerical study on the behavior of floating structures under challenging ocean conditions using WCSPH","authors":"Shayan Ramezanzadeh ,&nbsp;Murat Ozbulut ,&nbsp;Mehmet Yildiz","doi":"10.1016/j.jfluidstructs.2025.104273","DOIUrl":"10.1016/j.jfluidstructs.2025.104273","url":null,"abstract":"<div><div>The main objective of this study is to investigate the dynamic motions of floating bodies under different wave conditions. A particle-based numerical method, Smoothed Particle Hydrodynamics (SPH), is used due to its capabilities in modeling violent free surface flows. This work is based on five sub-steps. The first step focuses on ensuring the accuracy of the generated wave characteristics. Then, the heave motion of a point-absorber wave energy converter is examined under regular wave conditions with different power take-off (PTO) damping coefficients. After validating the proposed SPH scheme in a single degree of freedom motion, the roll decay of a rectangular floating body is investigated in the third step by comparing natural frequencies and damping coefficients with available literature data. Subsequently, the roll motion of a fixed floating structure under a wide-range regular wave system is simulated to obtain the corresponding Response Amplitude Operators (RAOs). Finally, the free body motion of a floating body under regular wave excitation is simulated and validated by experimental measurements, considering all rotational and translational motion characteristics. In the light of all simulation results, the proposed SPH numerical scheme can be considered as a useful tool for the design of effective and sustainable offshore structures.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104273"},"PeriodicalIF":3.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143394576","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":"Retro lock-in in the wake-induced vibration of a pair of tandem cylinders in close proximity","authors":"Gustavo R.S. Assi","doi":"10.1016/j.jfluidstructs.2025.104274","DOIUrl":"10.1016/j.jfluidstructs.2025.104274","url":null,"abstract":"<div><div>An experimental investigation performed at moderate Reynolds numbers was set to study how a pair of tandem cylinders can be excited into flow-induced vibrations by different interference mechanisms as a function of longitudinal spacings varying from 2 to 10 diameters. Results showed that the downstream cylinder could develop vortex-induced vibration (VIV) caused by its own vortex shedding, wake-induced vibration (WIV) caused by a developed wake formed in the gap, and gap-flow-switching. A combination of these mechanisms appeared for cases under close proximity. For a specific spacing of 3 diameters, the vibration of the downstream cylinder was able to synchronize the vortex shedding from the upstream, fixed body. We call this mechanism “retro lock-in” since the vortex-formation process of a bluff body was governed by the dynamics of another body located further downstream.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104274"},"PeriodicalIF":3.4,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143388302","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":"An efficient mode shape-based RBF mesh deformation approach via forward-backward greedy algorithm in CFD/CSD coupled simulation","authors":"Xuehan Gao ,&nbsp;Shun He ,&nbsp;Yingsong Gu","doi":"10.1016/j.jfluidstructs.2025.104276","DOIUrl":"10.1016/j.jfluidstructs.2025.104276","url":null,"abstract":"<div><div>Mesh deformation is an important element of CFD/CSD coupled time marching simulation. A mode shape-based Radial Basis Functions interpolation (M-RBF) approach is proposed to improve the efficiency of mesh deformation in the time marching simulation. Inspired by the modal expansion theorem in vibration theory, a set of interpolation nodes is pre-selected according to the mode shapes, rather than the physical displacements at each individual time step. The data reduction scheme of the forward-backward greedy algorithm is developed to select an optimum set of interpolation nodes. The AGARD 445.6 wing, a benchmark model for transonic flutter prediction, and the Goland+ wing with a tip store, which presents complexities in both aerodynamic configuration and mode shapes, are employed to validate the accuracy, efficiency, and capability of the M-RBF approach. The results show that the optimum set of interpolation nodes can achieve the desired interpolation accuracy while having little effect on the mesh quality at all time steps. The traditional RBF mesh deformation (T-RBF) and the RBF mesh deformation method via forward greedy algorithm (G-RBF) method spent majority of CPU time on the linear system solution (approximately 99% and 77.6%, respectively) and the selection of interpolation nodes (about 87.7% and 91.9%, respectively) in the case of AGARD 445.6 and Goland+ wing. However, by eliminating the need for repeated node selections, our M-RBF approach can improve the efficiency of mesh deformation by 2 to 3 orders of magnitude compared to the T-RBF method and 1 to 2 orders of magnitude compared to the G-RBF approach. The comparison of selected interpolation nodes by the M-RBF approach to the structural grid and CFD mesh indicates that the importance of nodes on the deforming boundary may be related to their distances from the structural grid.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104276"},"PeriodicalIF":3.4,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143345777","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":"Assessment of aeroelastic coupling between a shock boundary layer interaction and a flexible panel","authors":"Matthew J. Kronheimer,&nbsp;Jordan D. Thayer,&nbsp;Jack J. McNamara,&nbsp;Datta V. Gaitonde","doi":"10.1016/j.jfluidstructs.2025.104271","DOIUrl":"10.1016/j.jfluidstructs.2025.104271","url":null,"abstract":"<div><div>The fluid-structural coupling between an impinging Mach 4 shock boundary layer interaction (SBLI) and a flexible panel is investigated using wall-resolved implicit large-eddy simulation (ILES). Since the prediction of fluctuating wall pressure remains a challenge in aeroelastic configurations with large flow separation regions, an exposition of the coupling processes associated with the difference in the wall pressure fields between the coupled and uncoupled interaction is sought. The distinction between the time-mean pressure, induced coherent fluctuations, and inherent pressure fluctuations is formalized using a triple decomposition. Further, the role of the time-mean aeroelastic condition is considered to delineate predominantly static and dynamic coupling mechanisms between the fluid and structure. This is achieved by computing the fluid solution over the time-mean panel deformation of the coupled interaction. The impinging shock induces a large, highly unsteady separation region, the mean and fluctuating quantities of which are augmented by the imposed aeroelastic state. The use of the time-mean aeroelastic condition as a static structural deformation in a fluid-only simulation is found to capture the mean wall pressure of the coupled condition and some, but not all, of the increased flow unsteadiness. A local piston theory model is then implemented over a portion of the panel to assess the degree of flow unsteadiness associated with classical quasi-steady fluid-structural coupling between the supersonic ensemble-mean flow and the structural dynamics. It is found that, after the flow reattachment point, the coherent, dynamically induced pressure can be linearly superimposed with the statically coupled pressure field to predict the coupled wall pressure fluctuations to a reasonable degree.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104271"},"PeriodicalIF":3.4,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143345775","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":"Tornado-induced load distribution patterns and structural effects of a super large cooling tower","authors":"Xu Dong ,&nbsp;Lin Zhao ,&nbsp;Xu Chen ,&nbsp;Shikui Huang ,&nbsp;Mao Chen","doi":"10.1016/j.jfluidstructs.2025.104275","DOIUrl":"10.1016/j.jfluidstructs.2025.104275","url":null,"abstract":"<div><div>The investigation was physically and numerically conducted aiming at wind load distribution patterns and structural effects of a super large reinforced concrete cooling tower (SLRCCT) subjected to tornado-like vortices, and the influence of swirl ratios and the central distances between the SLRCCT and the tornado vortex core (TVC) were studied. The tornado-induced loads on the SLRCCT were firstly obtained based on rigid pressure measurement tests. Subsequently, tornado-induced structural displacement and internal force responses were analysed. It is revealed that the swirl ratios and the central distance between the SLRCCT and TVC significantly determine the tornado-induced load distributions and structural performances of the SLRCCT. Finally, an equivalent static wind load mode suitable for tornado resistance design of the SLRCCTs was proposed. Specifically, an empirical polynomial was suggested to fit the critical net wind pressure coefficient envelope. Wind vibration factor based on the evaluation criterion of time-variant dynamic reinforcement ratios was proposed to consider the fluctuating effects of the tornado, and the maximum tangential speed could be used to estimate the intensity influence of the tornado acting on the SLRCCT. This paper aims to contribute to a better understanding of the wind-related effects and the wind-resistant design of the SLRCCTs exposed to disaster-causing non-synoptic winds, particularly tornadoes.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104275"},"PeriodicalIF":3.4,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143345776","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":"Parallel water entry of hydrophobic-hydrophilic sphere pairings: particle image velocimetry and High-Speed camera analysis","authors":"Pooria Akbarzadeh ,&nbsp;Michael Krieger ,&nbsp;Dominik Hofer ,&nbsp;Maria Thumfart ,&nbsp;Philipp Gittler","doi":"10.1016/j.jfluidstructs.2025.104272","DOIUrl":"10.1016/j.jfluidstructs.2025.104272","url":null,"abstract":"<div><div>This study provides further investigation on parallel water entry of pairings of hydrophobic-hydrophilic spheres. In a prior publication by the current authors (Akbarzadeh et al., 2023), a distinct phenomenon termed “second pinch-off” was observed for certain scenarios of parallel water entry of equally-sized hydrophobic-hydrophilic spheres. This experimental study examines this event more comprehensively. Experiments with differently-sized spheres are also conducted and analyzed. In the equally-sized cases, two spheres with a diameter of <span><math><mrow><mn>20</mn><mtext>mm</mtext></mrow></math></span>, positioned in a lateral distance of 1.5 times the diameter, are released simultaneously from heights ranging from 25 to 55cm. This corresponds to impact velocities of <span><math><mrow><mn>2.21</mn><mo>∼</mo><mn>3.328</mn><mspace></mspace><mi>m</mi><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>. In these configurations, the vortex shedding behind the hydrophilic sphere significantly influences the air cavity produced by the hydrophobic sphere. A high-speed photography system, coupled with an image processing technique, is employed to analyze the event dynamics. Additionally, a Particle Image Velocimetry system is utilized to capture the flow field, extracting both velocity and vorticity fields. The analysis demonstrates that a vortex ring forms behind the hydrophilic sphere and causes some waviness in the cavity interface. This vortex ring is shed and migrates towards the cavity wall causing an indentation which grows over time and finally completely severs the air cavity (second pinch-off). Furthermore, the results highlight that the second pinch-off time, in non-dimensional form, correlates linearly with the impact Weber number. The findings for the case of differently-sized spheres (<span><math><mrow><mn>12</mn><mtext>mm</mtext></mrow></math></span> and <span><math><mrow><mn>20</mn><mtext>mm</mtext></mrow></math></span> in diameter), reveal that a second pinch-off event can also be observed in pairings where the smaller sphere is hydrophilic.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":"133 ","pages":"Article 104272"},"PeriodicalIF":3.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}