Journal of Fluids and Structures最新文献

{"title":"A new approach for spatio-temporal interface treatment in fluid–solid interaction using artificial neural networks employing coupled partitioned fluid–solid solvers","authors":"","doi":"10.1016/j.jfluidstructs.2024.104200","DOIUrl":"10.1016/j.jfluidstructs.2024.104200","url":null,"abstract":"<div><div>Partitioned fluid–solid interaction (FSI) problems involving non-conforming grids pose formidable challenge in interface treatment, especially for information exchange, interface tracking, and field variable interpolation between solvers in both space and time. These demand special considerations for accurate and efficient simulations. This paper presents an application of artificial neural networks (ANN) for the interface treatment in a coupled FSI problem employing partitioned solvers. A shallow time-series ANN (nonlinear auto-regressive model with exogenous inputs, NARX) scheme is proposed to handle the exchange of Neumann/Dirichlet information at the coupling interface. This scheme involves two interface treatment models that were developed and analysed. The proposed models interpolate and transfer loads from the fluid to the solid domains, and conversely, displacements from the solid to the fluid domains between non-collocated grids. To validate this approach, we tested it on a 3D FSI problem, which involved damped oscillations of a flexible flap submerged in a fluid cavity. Adequately trained NARX interface models demonstrate reliable input–output mapping and accurate prediction of transient behaviour at the interface. Additionally, we explored the concept of reduced-order modelling (ROM) in the time domain. This allowed us to reduce the model’s complexity by half. Different training algorithms were evaluated to enhance the efficiency and performance of the proposed scheme. The study demonstrates that NARX networks trained with Bayesian Regularization (BR) and Levenberg–Marquardt (LM) algorithms exhibit the best accuracy, while the scaled conjugate gradient (SCG)-based training method provides better computational efficiency with acceptable accuracy. Overall, the NARX interface models provide precise performance and offer a viable potential for applications in FSI problems requiring accurate and faster computations.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571756","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":"Condensation solution method for fluid-structure interaction dynamic models of structural system","authors":"","doi":"10.1016/j.jfluidstructs.2024.104214","DOIUrl":"10.1016/j.jfluidstructs.2024.104214","url":null,"abstract":"<div><div>In the fluid-structure dynamic analysis, the low solution efficiency seriously restricts the passive and active vibration control of structures. But so far, this issue has not been well addressed. Component mode synthesis (CMS) is an efficient method for dynamic analysis of structures. However, since the concept of mode for the fluid is very weak, the CMS is not suitable for solving fluid-structure interaction dynamic problems. Another type of dimension reduction method is dynamic condensation originating from Guyan method. In this paper, introducing the idea of CMS and combining the Guyan method, an efficient condensation solution method is proposed to solve the fluid-structure interaction dynamic models. In the dynamical modeling, both the structure field and fluid field are discretized using 20-node three dimensional elements. The elemental fluid-structure interaction equations of motion are formulated using the Hamilton principle and weighted residual method. The solid and fluid fields are divided into substructures, and all the degrees of freedom (DOFs) of the two fields are divided into interior structure DOFs, boundary structure DOFs, interior master fluid DOFs, interior salve fluid DOFs, as well as boundary fluid DOFs. In the solid substructures, higher orders of mode are neglected to realize a large-scale dimensional reduction, while for the fluid field, the slave DOFs are replaced by the master DOFs. To conduct the verification of the present method, experiment is carried out. The comparison results show the high accuracy and efficiency of the condensation solution method.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571754","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":"Turbulence-induced vibration in annular flow of a rigid cylinder mounted on a cantilever beam","authors":"","doi":"10.1016/j.jfluidstructs.2024.104213","DOIUrl":"10.1016/j.jfluidstructs.2024.104213","url":null,"abstract":"<div><div>This study investigates the fluid–structure interaction of two coaxial cylinders separated by a Newtonian fluid under turbulent axial flow. The theoretical framework treats the inner cylinder as a rigid body mounted on a flexible blade modeled as a Rayleigh beam. The goals of this study are to determine the free vibration modes and frequencies, identify the fluid-elastic instability threshold, and establish an analytical expression for the mean-square displacement of the structure. The approach integrates various fluid forces and torques, such as Archimedean thrust, fluid-elastic forces for a quiescent fluid, fluid-elastic forces due to flow, and the effects of fluid turbulence. The new approach reveals that vibration modes, frequencies, instability thresholds, and mean-square displacement each depend on a different set of dimensionless parameters: 8, 11, and 12, respectively. These parameters include the cylinder aspect ratio and fluid gap radius ratio. By incorporating models from the literature for viscous friction coefficients, turbulent pressure power spectral density, and coherence function, the study demonstrates stability conditions and the scaling of mean-square displacement with Reynolds number squared. The study, presented in a fully dimensionless formulation, aims to assist engineers in constructing small-scale experiments representative of pressure vessel vibrations. To facilitate this, a Python code for system stability determination and mean-square displacement calculation is provided.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571755","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":"Recurrent graph convolutional multi-mesh autoencoder for unsteady transonic aerodynamics","authors":"","doi":"10.1016/j.jfluidstructs.2024.104202","DOIUrl":"10.1016/j.jfluidstructs.2024.104202","url":null,"abstract":"<div><div>Unsteady, high-fidelity aerodynamic load predictions around a three-dimensional configuration will remain computationally expensive for the foreseeable future. Data-driven algorithms based on deep-learning are an attractive option for reduced order modelling of complex, nonlinear systems. However, a dedicated approach is needed for applicability to large and unstructured domains that are typical in engineering. This work presents a geometric-deep-learning multi-mesh autoencoder framework to predict the spatial and temporal evolution of aerodynamic loads for a finite-span wing undergoing different types of motion. The novel framework leverages on: (a) graph neural networks for aerodynamic surface grids embedded with a multi-resolution algorithm for dimensionality reduction; and (b) a recurrent scheme for time-marching the aerodynamic loads. The test case is for the BSCW wing in transonic flow undergoing a combination of forced-motions in pitch and plunge. A comprehensive comparison between a quasi-steady and a recurrent approach is provided. The model training requires four unsteady, high-fidelity aerodynamic analyses which require each about two days of HPC computing time. For any common engineering task that involves more than four cases, a clear benefit in computing costs is achieved using the proposed framework as an alternative predictive tool: new cases are computed in seconds on a standard GPU.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530946","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":"On the characteristics of fluid flow field and oscillatory response of tuned liquid multi-column dampers","authors":"","doi":"10.1016/j.jfluidstructs.2024.104206","DOIUrl":"10.1016/j.jfluidstructs.2024.104206","url":null,"abstract":"<div><div>The tuned liquid column damper (TLCD) operates as a fluid counterpart to a tuned mass damper (TMD), harnessing the dynamics of liquid flow to effectively counteract unwanted vibrations, thereby achieving the stability within the structural system. Most recently, to overcome the shortcoming that conventional TLCDs can only control the vibration of structures in a single direction, a toroidal tuned liquid multi-column damper (TLMCD) was proposed and its control effectiveness was preliminarily validated. However, the hydrodynamic characteristics of the TLMCD remain elusive and warrant further clarification. Therefore, this study employs computational fluid dynamics (CFD) methodology to meticulously simulate the intricate three-dimensional multiphase flow dynamics within toroidal TLMCDs across a spectrum of excitation conditions, aiming to elucidate their hydrodynamic behaviors. The efficacy of the CFD-based simulation approach is validated through a comparative analysis of numerically computed and experimentally measured liquid displacement responses. The error magnitude of the simplified theoretical model for toroidal TLMCDs is assessed by comparing the outcomes derived from CFD simulations with the theoretical predictions. Furthermore, by visualizing the spatial and temporal distribution of fluid flow field, the three-dimensional fluid flow properties of toroidal TLMCDs are characterized. The findings presented highlight the frequency-dependent nonlinear characteristics of liquid column oscillatory responses, providing a valuable benchmark for the development of more refined theoretical models and guiding the optimization of fluid-type dampers.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530947","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 novel semi-analytical approach based on scaled boundary finite element method for fluid-structure coupling analysis of liquid sloshing in 3D containers","authors":"","doi":"10.1016/j.jfluidstructs.2024.104205","DOIUrl":"10.1016/j.jfluidstructs.2024.104205","url":null,"abstract":"<div><div>In this paper, a novel semi-analytical approach is proposed for the three-dimensional fluid-structure coupling analysis of liquid sloshing in elastic containers subjected to harmonic and seismic loading in the horizontal direction, based on the scaled boundary finite element method (SBFEM). A modified SBFEM model, referred to as the scaling surface-based SBFEM, is developed to simulate the container wall, which is treated as a thin shell structure. Within the framework of the scaling surface-based SBFEM, the geometry of the shell structure is entirely determined by scaling one surface of the structure. This approach differs significantly from the standard SBFEM, where approximation is achieved through coordinate mapping based on a scaling center, thereby enhancing the modeling accuracy and efficiency. Hydrodynamic pressure is treated as an independent nodal variables in the governing equations of the fluid domain, which is modeled using the standard scaling centre-based SBFEM. The coupled fluid-structure system is assembled by applying equilibrium and compatibility boundary conditions to ensure the balance of interaction forces. A synchronous solution algorithm, combined with the implicit-implicit scheme of the Newmark method, is used to determine the dynamic responses of the coupled system. The main advantage of this novel approach is that it meshes and discretizes the boundaries instead of the entire structural and fluid domains, thereby reducing computational costs. Additionally, analytical solutions can be obtained along the radial direction of the interior domain, enhancing the accuracy and convergence of the results. Another advantage is the approach's ability to provide a unified modeling framework for structures of any shape. Furthermore, the asymmetry issue of the coefficient matrix can be effectively avoided by using a synchronous solution algorithm. Benchmark examinations confirm the superior computational accuracy and robustness of the proposed approach. A comprehensive parametric study is conducted, focusing on the effects of liquid filling levels, as well as geometric and material parameters, on the transient vibration and distribution behaviors of the fluid-structure coupling system.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530945","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":"Flow past a freely vibrating elliptic cylinder at 45∘ incidence","authors":"","doi":"10.1016/j.jfluidstructs.2024.104201","DOIUrl":"10.1016/j.jfluidstructs.2024.104201","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Undamped transverse-only flow-induced vibrations (FIV) of an elliptic cylinder of mass ratio, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; at 45° incidence are investigated via two-dimensional computations at Reynolds numbers, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and 200. Using quasi-steady theory, it is illustrated that the asymmetric oscillator does not gallop at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and 200. Resolution of hysteresis-free solutions at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is a novel finding. As compared to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, response at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;200&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is associated with additional branches: a lower branch, a terminal branch and a third regime of desynchronization. Assuming harmonic lift and response, mathematical expressions are obtained for modified dimensionless circular frequency, &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ω&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and modified damping. The variation of &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ω&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; with reduced speed, &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; reveals excellent collapse with predicted dynamic response. For FIV at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;200&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and not at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, a second regime of significant vibrations develops in the neighbourhood of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; in addition to the first one around &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The period doubling bifurcation occurring around &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is an 1:2 sub-harmonic synchronization; it halves the oscillation frequency that in turn closely approaches reduced natural frequency of the cylinder. In this regime, the wake mode is found to be 2(2S). Leontini et al. (2018) resolved periodic doubling bifurcation for FIV of an inclined elliptic cylinder using a low &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; of unity. The occurrences of second lock-in and period doubling therefore appear not to be a function of &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442877","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":"Spanwise variations in membrane flutter dynamics","authors":"","doi":"10.1016/j.jfluidstructs.2024.104194","DOIUrl":"10.1016/j.jfluidstructs.2024.104194","url":null,"abstract":"<div><div>We study the large-amplitude flutter of rectangular membranes in 3-D inviscid flows. The membranes’ deformations vary significantly in both the chordwise and spanwise directions. Many previous studies used 2D flow models and neglected spanwise variations, so here we focus on cases with significant spanwise nonuniformity. We determine when such cases occur and how the dynamics vary over the parameter space of membrane mass and pretension for two sets of boundary conditions and two values of both the Poisson ratio and the membrane aspect ratio. With spanwise symmetric and asymmetric initial perturbations, the motions differ for long times but eventually reach the same steady state in most cases.</div><div>At large times, spanwise symmetric and asymmetric oscillations are seen, with the latter more common. Oscillations are often in the form of “side-to-side” and other standing wave motions along the span, as well as traveling wave motions, particularly with free side-edges. Motions are generally nonperiodic and more spatially complex with a large membrane mass, and sometimes periodic at small-to-moderate membrane mass. A large Poisson ratio gives somewhat smoother spatial and temporal features in the dynamics at a given pretension. Increasing the aspect ratio makes the deflection more uniform along the span. With different chordwise and spanwise pretensions we find motions that are qualitatively similar to cases with isotropic pretensions between the anisotropic values.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432760","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":"Fluid-structure interaction among three tandem circular cylinders oscillating transversely at a low Reynolds number of 150","authors":"","doi":"10.1016/j.jfluidstructs.2024.104204","DOIUrl":"10.1016/j.jfluidstructs.2024.104204","url":null,"abstract":"<div><div>The flow-induced vibration (FIV) of three tandem circular cylinders is numerically investigated using OpenFOAM based on the finite-volume method. The one-degree-of-freedom dynamic response of three tandem circular cylinders with a spacing ratio ranging from 2 to 6 is analysed at a low Reynolds number of 150 over a reduced velocity range of 2–16. The results of hydrodynamic coefficients, response amplitude, vibration frequency, wake structure, and decomposition of vorticity are discussed in this study. Although the streamwise spacing ratio is constant, the dynamic evolution of the crossing angles among three cylinders leads to the switching of wake interference mode. The two-layered vortices are merged into secondary vortices in the far wake, and the energy of secondary vortices is higher than the two-layered vortices. The upstream cylinder exhibits a similar trend as an isolated cylinder in terms of the variations of hydrodynamic coefficients and response amplitude with the reduced velocity. In contrast, the middle and downstream cylinders experience a significantly lower drag due to the shielding effect. Particularly at small spacing ratios, the drag on the middle cylinder becomes negative. At the same time, the lift coefficient and response amplitude are higher than those of an isolated cylinder at high reduced velocities. The three tandem cylinders intermittently form a triangular configuration during the oscillation.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426890","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":"Multistable dynamic behaviors of cantilevered curved pipes conveying fluid","authors":"","doi":"10.1016/j.jfluidstructs.2024.104196","DOIUrl":"10.1016/j.jfluidstructs.2024.104196","url":null,"abstract":"<div><div>The present study newly found multistable dynamic characteristics of cantilevered curved pipes conveying fluid due to the gravity. These multistable behaviors of the pipe offer a promising avenue for the development and deployment of fluid actuators. Three configurations of curved pipes, namely, one-quarter circular, semi-circular, and three-quarter circular, are considered. A nonlinear dynamic theoretical model is established based on the geometrically exact model to investigate the large deformation behaviors of the curved pipe conveying subcritical fluid flows. The theoretical model for predicting large deformations of the curved pipe is validated through the finite element method (FEM). Afterwards, linear dynamic characteristics for three configurations of curved pipes are explored. Strangely, the discontinuity phenomenon for natural frequencies of the curved pipe occurs with increasing the flow velocity, which has never been reported before. Meanwhile, it is demonstrated that the gravity parameter has a significant effect on the critical velocity for flutter. Large deformation responses of the curved pipe in three configurations are further investigated, multistable dynamic behaviors are detected for all considered curved pipes. It displays that for different gravity parameters, the dynamic behavior of curved pipe is varying from a single state to multiple states with increasing the flow velocity. Results indicate that when the dimensionless gravity parameter and fluid velocity are 15 and 2.5, the curved pipe exhibits three distinct displacements due to static deformations. These three displacements are in three equilibrium states, which helps to explain the interesting phenomenon of frequency discontinuity.</div></div>","PeriodicalId":54834,"journal":{"name":"Journal of Fluids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426886","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}