Journal articles on the topic 'Flow; cylinders; induced vibration'
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1
Qin, Bin, Md Mahbub Alam, and Yu Zhou. "Free vibrations of two tandem elastically mounted cylinders in crossflow." Journal of Fluid Mechanics 861 (December 21, 2018): 349–81. http://dx.doi.org/10.1017/jfm.2018.913.
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The paper presents an experimental investigation on the flow-induced vibrations of two tandem circular cylinders for spacing ratio $L/D=1.2{-}6.0$ and reduced velocity $U_{r}=3.8{-}47.8$, where $L$ is the cylinder centre-to-centre spacing and $D$ is the cylinder diameter. Both cylinders are allowed to vibrate only laterally. Extensive measurements are conducted to capture the cylinder vibration and frequency responses, surface pressures, shedding frequencies and flow fields using laser vibrometer, hotwire, pressure scanner and PIV techniques. Four vibration regimes are identified based on the characteristics and generation mechanisms of the cylinder galloping vibrations. Several findings are made on the mechanisms of vibration generation and sustainability. First, the initial states (vibrating or fixed) of a cylinder may have a pronounced impact on the vibration of the other. Second, alternating reattachment, detachment, rolling up and shedding of the upper and lower gap shear layers all contribute to the vibrations. Third, the gap vortices around the base surface of the upstream cylinder produce positive work on the cylinder, sustaining the upstream cylinder vibration. Fourth, reattachment, detachment and switching of the gap shear layers result in largely positive work on the downstream cylinder, playing an important role in sustaining its vibration.
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Shao, Ze, Tongming Zhou, Hongjun Zhu, Zhipeng Zang, and Wenhua Zhao. "Amplitude Enhancement of Flow-Induced Vibration for Energy Harnessing." E3S Web of Conferences 160 (2020): 01005. http://dx.doi.org/10.1051/e3sconf/202016001005.
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In this paper, flow-induced vibrations of bluff bodies with four different cross-sectional geometries (circle, square, triangle and semi-circle) arranged both in single and tandem (gap ratio equals to 3 and 5) configurations are investigated in a wind tunnel. It is found that triangular and square cylinders have the higher amplitude than that of the semi-circular and the circular cylinders in the single configuration. When two cylinders are arranged in tandem, the circular cylinders have the highest amplitude among all tested cylinders. Furthermore, the semi-circular cylinder shows that its vibrating amplitude increases with the reduced velocity in the tandem system due to the galloping effect.
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Jiang, Ren-Jie. "Flow-induced vibrations of two tandem cylinders in a channel." Thermal Science 16, no. 5 (2012): 1377–81. http://dx.doi.org/10.2298/tsci1205377j.
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We numerically studied flow-induced vibrations of two tandem cylinders in transverse direction between two parallel walls. The effect of the horizontal separation between two cylinders, ranging from 1.1 to 10, on the motions of the cylinders and the flow structures were investigated and a variety of periodic and non-periodic vibration regimes were observed. The results show that when two cylinders are placed in close proximity to each other, compared with the case of an isolated cylinder, the gap flow plays an important role. As the separation ratio is increased, the fluid-structure interaction decouples and the cylinders behave as two isolated cylinders.
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Wang, Chaoqun, Xugang Hua, Zhiwen Huang, and Qing Wen. "Aerodynamic Characteristics of Coupled Twin Circular Bridge Hangers with Near Wake Interference." Applied Sciences 11, no. 9 (May 4, 2021): 4189. http://dx.doi.org/10.3390/app11094189.
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Much work has been devoted to the investigation and understanding of the flow-induced vibrations of twin cylinders vibrating individually (e.g., vortex-induced vibration and wake-induced galloping), but little has been devoted to coupled twin cylinders with synchronous galloping. The primary objective of this work is to investigate the aerodynamic forcing characteristics of coupled twin cylinders in cross flow and explore their effects on synchronous galloping. Pressure measurements were performed on a stationary section model of twin cylinders with various cylinder center-to-center distances from 2.5 to 11 diameters. Pressure distributions, reduced frequencies and total aerodynamic forces of the cylinders are analyzed. The results show that the flow around twin cylinders shows two typical patterns with different spacing, and the critical spacing for the two patterns at wind incidence angles of 0° and 9° is in the range of 3.8D~4.3D and 3.5D~3.8D, respectively. For cylinder spacings below the critical value, vortex shedding of the upstream cylinder is suppressed by the downstream cylinder. In particular, at wind incidence angles of 9°, the wake flow of the upstream cylinder flows rapidly near the top edge and impacts on the inlet edge of the downstream cylinder, which causes a negative and positive pressure region, respectively. As a result, the total lift force of twin cylinders comes to a peak while the total drag force jumps to a higher value. Moreover, there is a sharp drop of total lift coefficient for α = 9–12°, indicating the potential galloping instability. Finally, numerical simulations were performed for the visualization of the two flow patterns.
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Chen, S. S. "Flow-Induced Vibrations in Two-Phase Flow." Journal of Pressure Vessel Technology 113, no. 2 (May 1, 1991): 234–41. http://dx.doi.org/10.1115/1.2928751.
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Two-phase flow exists in many shell-and-tube heat exchangers and power generation components. The flowing fluid is a source of energy that can induce small-amplitude subcritical oscillations and large-amplitude dynamic instabilities. In fact, many practical system components have experienced excessive flow-induced vibrations. This paper reviews the current understanding of vibration of circular cylinders in quiescent fluid, cross-flow, and axial flow, with emphasis on excitation mechanisms, mathematical models, and available experimental data. A unified theory is presented for cylinders oscillating under different flow conditions.
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Junwu, Wu, and Yin Zhongjun. "Numerical Investigation on Vortex-Induced Vibration Energy Extraction Efficiency of Double Circular Cylinders In Tandem Arrangement at Low Reynolds Number." MATEC Web of Conferences 153 (2018): 05001. http://dx.doi.org/10.1051/matecconf/201815305001.
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Vortex shedding from a bluff body results in fluctuating forces acting on the bluff body, which may induce vibration of the bluff body when the bluff body is elastically mounted or deformable. Researchers put forward an idea that we can ex-tract energy from the water flow based on VIV at low flow velocity. Although plenty of researches on parameters of VIV are already presented, however, the improvement of energy extraction efficiency still needs further study. According to the previous research, this essay has simulated flow-induced vibration of tandem double circular cylinders when Reynolds number is 100. Working condition has been considered as the fixed upstream cylinder and the free vibration of the downstream cylinder. The influence of the mass coefficient and the two cylinders spacing ratio on the downstream cylinder’s energy obtained from the fluid is studied. Analysis results show that, the maximum value of the energy extraction efficiency is before the frequency locked range. In the case of large spacing ratio (L/D=7~9), the phenomenon of "beat vibration" appears on the downstream cylinder. The results of this work could provide reference for the improvement of energy extraction efficiency and the design of VIV converter.
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Chen, S. S. "A Review of Flow-Induced Vibration of Two Circular Cylinders in Crossflow." Journal of Pressure Vessel Technology 108, no. 4 (November 1, 1986): 382–93. http://dx.doi.org/10.1115/1.3264802.
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The flow field around a pair of rigid circular cylinders is very complex and has been studied extensively. When either one or both cylinders vibrate, the flow field becomes significantly more complicated because of the interaction of the fluid flow and the cylinder motion. This paper presents an overview of the problem including different flow regimes, vortex-excited vibration, and fluidelastic instability for two cylinders in tandem, two cylinders side by side and two cylinders in staggered arrangement. A general formulation to study dynamic response under different conditions is outlined and future research needs are discussed.
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Ghabuzyan, Levon, Christopher Luengas, and Jim Kuo. "Urban Wind Harvesting Using Flow-Induced Vibrations." American Journal of Undergraduate Research 16, no. 4 (March 15, 2020): 71–79. http://dx.doi.org/10.33697/ajur.2020.008.
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The growing global interest in sustainable energy has paved the way to the rapid development of large-scale wind farms, consisting of dozens to hundreds of wind turbines. Although these large wind farms can generate enormous amount of power, they are also costly and require large areas of land or water, and thus are not suitable for urban environments. Smaller urban wind turbines have been developed for urban environments, but there are significant challenges to their widespread deployment. One of these challenges are their urban wind flows as they are strongly affected by complex building structures, producing highly turbulent flows. Any urban wind turbine would need to be designed to function efficiently and safely under these flow conditions; however, these unpredictable and turbulent winds can induce undesirable vibrations and cause early failures. Recently, bladeless wind turbines are gaining interest due to their reduced costs compared with conventional wind turbines such as the vertical-axis wind turbine and horizontal-axis wind turbine. These bladeless turbines convert flow wind energy into vibration energy, then converts the vibration energy into electricity. This paper examines the effects of force-induced vibrations on a cantilever beam system through wind tunnel experimentation. When fluid flows around a bluff body, periodic shedding of vortices may occur under the right conditions. The vortex shedding process creates an asymmetric pressure distribution on the body which causes the body to oscillate, known as vortex-induced vibrations. The purpose of the paper is to understand the factors affecting flow-induced vibrations and to improve wind energy harvesting from these vibrations. The first part of the paper focuses on wind tunnel experiments, by utilizing a cantilever beam configuration, conceptualized by previous research. Then, the experimental model was tested in different configurations, to determine the best setup for maximizing vibrations induced on the model. The long-term goal of the project was utilizing the model to optimize the system to improve efficiency of wind energy harvesting. The experimental results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibration for energy harvesting, furthermore, the experiments showed that spacing in different directions also affect the amplitude of the vibrations. A two tandem cylinder system was used in this work, including a fixed rigid upstream cylinder and a downstream cylinder supported by a cantilever beam. Various configurations of these two cylinders in terms of spanwise and streamwise separation distances were studied and their maximum and root mean square displacements are reported for different wind speeds. Results showed that the presence of an upstream cylinder will significantly improve the amplitude of vibrations. This work verified that a wind energy harvester needs to consider the effects of wind speed and separation configuration of the cylinders in order to maximize the harvester’s performance in urban environments. KEYWORDS: Sustainable Energy; Energy Harvesting; Urban Environments; Bladeless Wind Turbines; Flow-Induced Vibrations; Cantilever Beam System; Wind Tunnel; Wake
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Sakai, Takaaki, Masaki Morishita, Koji Iwata, and Seiji Kitamura. "Experimental Study on the Avoidance and Suppression Criteria for the Vortex-Induced Vibration of a Cantilever Cylinder." Journal of Pressure Vessel Technology 124, no. 2 (May 1, 2002): 187–95. http://dx.doi.org/10.1115/1.1465436.
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Experimental validation of the design guideline to prevent the failure of a thermometer well by vortex-induced vibration is presented, clarifying the effect of structure damping on displacement amplitudes of a cantilever cylinder. The available experimental data in piping are limited to those with small damping in water flow, because of the difficulty in increasing structure damping of the cantilever cylinders in experiments. In the present experiment, high-viscosity oil within cylinders is used to control their structure damping. Resulting values of reduced damping Cn are 0.49, 0.96, 1.23, 1.98, and 2.22. The tip displacements of the cylinder induced by vortex vibration were measured in the range of reduced velocity Vr from 0.7 to 5 (Reynolds number is 7.8×104 at Vr=1). Cylinders with reduced damping 0.49 and 0.96 showed vortex-induced vibration in the flow direction in the Vr>1 region. However, in cases of reduced damping of 1.23, 1.98, and 2.22, the vibration was suppressed to less than 1 percent diameter. It is confirmed that the criteria of “Vr<3.3 and Cn>1.2” for the prevention of vortex-induced vibration is reasonably applicable to a cantilever cylinder in a water flow pipe.
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Ali, Ussama, Md Islam, Isam Janajreh, Yap Fatt, and Md Mahbub Alam. "Flow-Induced Vibrations of Single and Multiple Heated Circular Cylinders: A Review." Energies 14, no. 24 (December 16, 2021): 8496. http://dx.doi.org/10.3390/en14248496.
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This study is an effort to encapsulate the fundamentals and major findings in the area of fluid-solid interaction, particularly the flow-induced vibrations (FIV). Periodic flow separation and vortex shedding stretching downstream induce dynamic fluid forces on the bluff body and results in oscillatory motion of the body. The motion is generally referred to as flow-induced vibrations. FIV is a dynamic phenomenon as the motion, or the vibration of the body is subjected to the continuously changing fluid forces. Sometimes FIV is modeled as forced vibrations to mimic the vibration response due to the fluid forces. FIV is a deep concern of engineers for the design of modern heat exchangers, particularly the shell-and-tube type, as it is the major cause for the tube failures. Effect of important parameters such as Reynolds number, spacing ratio, damping coefficient, mass ratio and reduced velocity on the vibration characteristics (such as Strouhal number, vortex shedding, vibration frequency and amplitude, etc.) is summarized. Flow over a bluff body with wakes developed has been studied widely in the past decades. Several review articles are available in the literature on the area of vortex shedding and FIV. None of them, however, discusses the cases of FIV with heat transfer. In particular systems, FIV is often coupled to heat transfer, e.g., in nuclear power plants, FIV causes wear and tear to heat exchangers, which can eventually lead to catastrophic failure. As the circular shape is the most common shape for tubes and pipes encountered in practice, this review will only focus on the FIV of circular cylinders. In this attempt, FIV of single and multiple cylinders in staggered arrangement, including tandem and side-by-side arrangement is summarized for heated and unheated cylinder(s) in the one- and two-degree of freedom. The review also synthesizes the effect of fouling on heat transfer and flow characteristics. Finally, research prospects for heated circular cylinders are also stated.
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Griffith, Martin D., David Lo Jacono, John Sheridan, and Justin S. Leontini. "Flow-induced vibration of two cylinders in tandem and staggered arrangements." Journal of Fluid Mechanics 833 (November 2, 2017): 98–130. http://dx.doi.org/10.1017/jfm.2017.673.
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A numerical study of the flow-induced vibration of two elastically mounted cylinders in tandem and staggered arrangements at Reynolds number $Re=200$ is presented. The cylinder centres are set at a streamwise distance of 1.5 cylinder diameters, placing the rear cylinder in the near-wake region of the front cylinder for the tandem arrangement. The cross-stream or lateral offset is varied between 0 and 5 cylinder diameters. The two cylinders are identical, with the same elastic mounting, and constrained to oscillate only in the cross-flow direction. The variation of flow behaviours is examined for static cylinders and for elastic mountings of a range of spring stiffnesses, or reduced velocity. At least seven major modes of flow response are identified, delineated by whether the oscillation is effectively symmetric, and the strength of the influence of the flow through the gap between the two cylinders. Submodes of these are also identified based on whether or not the flow remains periodic. More subtle temporal behaviours, such as period doubling, quasi-periodicity and chaos, are also identified and mapped. Across all of these regimes, the amplitudes of vibration and the magnitude of the fluid forces are quantified. The modes identified span the parameter space between two important limiting cases: two static bodies at varying lateral offset; and two elastically mounted bodies in a tandem configuration at varying spring stiffnesses. Some similarity in the response of extremely stiff or static bodies and extremely slack bodies is shown. This is explained by the fact that the slack bodies are free to move to an equilibrium position and stop, effectively becoming a static system. However, the most complex behaviour appears between these limits, when the bodies are in reasonably close proximity, and the natural structural frequency is close to the vortex shedding frequency of a single cylinder. This appears to be driven by the interplay between a series of time scales, including the vortex formation time, the advection time across the gap between the cylinders and the oscillation period of both bodies. This points out an important difference between this multi-body system and the classic single-cylinder vortex-induced vibration: two bodies in close proximity will not oscillate in a synchronised, periodic manner when their natural structural frequencies are close to the nominal vortex shedding frequency of a single cylinder.
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Xie, Fangfang, Dingyi Pan, Yao Zheng, and Jianfeng Zou. "Smoothed profile method and its applications in VIV." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 7 (July 3, 2017): 1623–35. http://dx.doi.org/10.1108/hff-12-2016-0503.
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Purpose The purpose of this paper is to propose a partitioned approach by coupling the smoothed profile method (SPM) and the Euler tension beam model in simulating a vortex-induced vibration of both rigid and flexible cylinders at various reduced velocities. Design/methodology/approach For the fluid part, SPM in the framework of the spectral element method is adopted to simulate the flow. The advantage of SPM lies in modelling multiple complex shapes as it uses a fixed computational mesh without conformation to the geometry of the particles. For the structure part, an elastic-mounted rigid cylinder is considered in two-dimensional (2D) simulations, while a flexible cylinder with a Euler tension beam model is used in three-dimensional simulations. Findings Firstly, in the flow past a freely vibrating cylinder, the maximum vibration responses of the cylinder are about 0.73D and 0.1D in the y and x directions, respectively, which occur at the point Ur = 5.75 and are much higher than Ur = 5 in 2D simulations. It is found that the numerical results from the SPM solver are very consistent with those from the NEKTAR-Arbitrary Lagrangian Eulerian method (NEKTAR-ALE) solver or the NEKTAR-Fourier solver. Furthermore, the flow past the tandem cylinders is also investigated, where the upstream cylinder is static while the downstream one is free to vibrate. Specifically, the beating behaviour is captured from the vibration response of the freely vibrating cylinder under the reduced velocity of Ur = 6 with a gap distance of L = 3.5D. Originality/value The originality of the paper lies in coupling the SEM with the Euler beam model in simulating the vortex induced vibration (VIV) of flexible cylinders.
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Wang, Z. J., Y. Zhou, and R. M. C. So. "Vortex-Induced Vibration Characteristics of Two Fixed-Supported Elastic Cylinders." Journal of Fluids Engineering 125, no. 3 (May 1, 2003): 551–60. http://dx.doi.org/10.1115/1.1568360.
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Interference effects on vortex-induced vibrations of two side-by-side elastic cylinders, fixed at both ends (with no deflection and displacement) in a cross-flow, were experimentally investigated. The dynamic responses of the cylinders were measured using two fiber-optic Bragg grating (FBG) sensors. Simultaneously, a single hot wire was used to measure the velocity in the wake. It has been previously observed that violent resonance occurs when transverse cylinder spacing ratio, T/d, is either large (>2.0) or small (<1.2), but not for intermediate cylinder spacing, i.e., T/d=1.2∼2.0. This work aims to improve the understanding of the physics behind this observation, and mostly focuses on the fluid-structure interaction in the flow regime of intermediate cylinder spacing. It is well known that in this flow regime the fluid dynamics around one cylinder is totally different from that around the other; the vortical structures are characterized by different dominant frequencies, i.e., about 0.1 and 0.3 (normalized), respectively. The present data indicates that the vortical structures at these frequencies are either weak or different in the formation process from the case of T/d>2.0 or T/d<1.2, thus resulting in a weak excitation and subsequently an absence of violent resonance. The interrelationship between the vortical structures generated by the two cylinders is also investigated and interpreted in terms of different vortex generation mechanisms. The different fluid dynamics around each cylinder is further found to be responsible for a deviation between the natural frequencies of the combined fluid-cylinder system associated with each cylinder.
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Yang, Zuo-Mei, Lin Ding, Qian-Yun Ye, Lin Yang, and Li Zhang. "Effect of Gap Flow on the Characteristics of Flow-Around and Flow-Induced Vibration for Two Circular Cylinders with Roughness Strips." Applied Sciences 9, no. 17 (September 2, 2019): 3587. http://dx.doi.org/10.3390/app9173587.
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In order to understand the gap flow between two cylinders, the characteristics of flow around two stationary cylinders and the flow-induced vibration of two staggered cylinders with roughness strips are numerically studied. The lift–drag responses, Strouhal number (St) and wake structure of two stationary cylinders in tandem, as well as the vibration response and vortex pattern of two oscillating staggered cylinders are analyzed. The results indicate that the spacing dc of two stationary cylinders at which the gap flow can be observed is different for different Re, and dc is 3D when Re = 2000 and dc = 2.5D at Re = 6000~14,000. When the distance d = dc, the force coefficient and St of two cylinders increase sharply. For the two oscillating staggered cylinders, there is a critical reduced velocity Uc* = 7, which makes the amplitude magnitude relationship of the two cylinders change. With the change of the reduced velocity, the vibration frequencies of the two cylinders are consistent. When the staggered distance increases, the frequency difference of the two cylinders decreases. At the same inflow velocity, with the increase of staggered distance, a gap flow is formed between the two cylinders. When T > 0.6D and U* < 8, the gap flow becomes the main factor affecting the vibration of the two cylinders, which can be divided into the dominant region of gap flow.
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BORAZJANI, IMAN, and FOTIS SOTIROPOULOS. "Vortex-induced vibrations of two cylinders in tandem arrangement in the proximity–wake interference region." Journal of Fluid Mechanics 621 (February 12, 2009): 321–64. http://dx.doi.org/10.1017/s0022112008004850.
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We investigate numerically vortex-induced vibrations (VIV) of two identical two-dimensional elastically mounted cylinders in tandem in the proximity–wake interference regime at Reynolds number Re = 200 for systems having both one (transverse vibrations) and two (transverse and in-line) degrees of freedom (1-DOF and 2-DOF, respectively). For the 1-DOF system the computed results are in good qualitative agreement with available experiments at higher Reynolds numbers. Similar to these experiments our simulations reveal: (1) larger amplitudes of motion and a wider lock-in region for the tandem arrangement when compared with an isolated cylinder; (2) that at low reduced velocities the vibration amplitude of the front cylinder exceeds that of the rear cylinder; and (3) that above a threshold reduced velocity, large-amplitude VIV are excited for the rear cylinder with amplitudes significantly larger than those of the front cylinder. By analysing the simulated flow patterns we identify the VIV excitation mechanisms that lead to such complex responses and elucidate the near-wake vorticity dynamics and vortex-shedding modes excited in each case. We show that at low reduced velocities vortex shedding provides the initial excitation mechanism, which gives rise to a vertical separation between the two cylinders. When this vertical separation exceeds one cylinder diameter, however, a significant portion of the incoming flow is able to pass through the gap between the two cylinders and the gap-flow mechanism starts to dominate the VIV dynamics. The gap flow is able to periodically force either the top or the bottom shear layer of the front cylinder into the gap region, setting off a series of very complex vortex-to-vortex and vortex-to-cylinder interactions, which induces pressure gradients that result in a large oscillatory force in phase with the vortex shedding and lead to the experimentally observed larger vibration amplitudes. When the vortex shedding is the dominant mechanism the front cylinder vibration amplitude is larger than that of the rear cylinder. The reversing of this trend above a threshold reduced velocity is associated with the onset of the gap flow. The important role of the gap flow is further illustrated via a series of simulations for the 2-DOF system. We show that when the gap-flow mechanism is triggered, the 2-DOF system can develop and sustain large VIV amplitudes comparable to those observed in the corresponding (same reduced velocity) 1-DOF system. For sufficiently high reduced velocities, however, the two cylinders in the 2-DOF system approach each other, thus significantly reducing the size of the gap region. In such cases the gap flow is entirely eliminated, and the two cylinders vibrate together as a single body with vibration amplitudes up to 50% lower than the amplitudes of the corresponding 1-DOF in which the gap flow is active. Three-dimensional simulations are also carried out to examine the adequacy of two-dimensional simulations for describing the dynamic response of the tandem system at Re = 200. It is shown that even though the wake transitions to a weakly three-dimensional state when the gap flow is active, the three-dimensional modes are too weak to affect the dynamic response of the system, which is found to be identical to that obtained from the two-dimensional computations.
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Zhang, Min, and Junlei Wang. "Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations." Journal of Sensors 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/2673292.
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A rigid circular cylinder with two piezoelectric beams attached on has been tested through vortex-induced vibrations (VIV) and wake-induced vibrations (WIV) by installing a big cylinder fixed upstream, in order to study the influence of the different flow-induced vibrations (FIV) types. The VIV test shows that the output voltage increases with the increases of load resistance; an optimal load resistance exists for the maximum output power. The WIV test shows that the vibration of the small cylinder is controlled by the vortex frequency of the large one. There is an optimal gap of the cylinders that can obtain the maximum output voltage and power. For a same energy harvesting device, WIV has higher power generation capacity; then the piezoelectric output characteristics can be effectively improved.
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Hotta, Shusaku, Xu Qiang, Satoshi Someya, and Koji Okamoto. "ICONE19-43958 Experimental investigation of flow-induced vibration interference between two tandem circular cylinders." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2011.19 (2011): _ICONE1943. http://dx.doi.org/10.1299/jsmeicone.2011.19._icone1943_356.
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Qin, Bin, Md Mahbub Alam, and Yu Zhou. "Two tandem cylinders of different diameters in cross-flow: flow-induced vibration." Journal of Fluid Mechanics 829 (September 22, 2017): 621–58. http://dx.doi.org/10.1017/jfm.2017.510.
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This paper presents a systematic study of the cross-flow-induced vibration on a spring-supported circular cylinder of diameter $D$ placed in the wake of a fixed cylinder of smaller diameter $d$. The ratios $d/D$ and $L/d$ are varied from 0.2 to 1.0 and from 1.0 to 5.5, respectively, where $L$ is the distance between the centre of the upstream cylinder to the forward stagnation point of the downstream cylinder. Extensive measurements are conducted to capture the cylinder vibration and frequency responses, surface pressure, shedding frequencies and flow fields using laser vibrometer, hot-wire, pressure scanner and particle image velocimetry techniques. Six distinct flow regimes are identified. It has been found that a violent vibration may erupt for the spring-supported cylinder, and its dependence on $d/D$ and $L/d$ is documented. A careful examination and analysis of the flow structure, along with the simultaneously captured pressure distribution around and vibration of the downstream cylinder, cast light upon the mechanisms behind this vibration and its sustainability. The roles of added mass, flow-induced damping and physical aspects in the process of initiating the vibration are discussed in detail.
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Gołębiowska, Irena, Maciej Dutkiewicz, Tomasz Lamparski, and Poorya Hajyalikhani. "Vibrations of Slender Structures Caused by Vortices." IOP Conference Series: Materials Science and Engineering 1203, no. 2 (November 1, 2021): 022025. http://dx.doi.org/10.1088/1757-899x/1203/2/022025.
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Abstract Slender cylindrical structures such as overhead transmission lines, skyscrapers, chimneys, risers, and pipelines can experience flow induced vibration (FIV). The vortex vibrations are a type of FIV; they arise because of oscillating forces caused by flow separation and the detachment of vortices. The paper presents a brief overview of experimental research on vortex induced vibration - VIV of short, rigid cylinders elastically supported (with a small aspect ratio). This overview summarizes the basic results of the vortex vibration (VIV) which have been performed in the last five decades. These studies were mainly related to determining the influence of selected parameters - mass, damping and Reynolds number on the cylinder response, either in one direction only or simultaneously in the flow direction and transverse to the flow direction, and with the search for a map of vortex images in the trace (vortex wake pattern map).
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Ding, Lin, Qunfeng Zou, Li Zhang, and Haibo Wang. "Research on Flow-Induced Vibration and Energy Harvesting of Three Circular Cylinders with Roughness Strips in Tandem." Energies 11, no. 11 (November 1, 2018): 2977. http://dx.doi.org/10.3390/en11112977.
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The flow-induced vibration (FIV) of multiple cylinders is a common phenomenon in industry and nature. The FIV and energy harvesting of three circular cylinders in tandem are numerically studied by 2D-URANS simulations in Reynolds number range of 30,000 < Re < 105,000. Simulation results match well with experiments in the tested cases. Four branches of FIV are clearly captured in the amplitude and frequency ratio curves of the three cylinders with roughness, including initial branch of vortex-induced vibration (VIV), VIV upper branch, transition from VIV to galloping, and galloping. It is shown that the vortices from downstream cylinder are strongly disrupted and modified by vortices of upstream cylinder. The third cylinder is almost suppressed in VIV initial branch. The 2P vortex pattern is observed for the first cylinder in the VIV upper branch. For Re = 90,000 in the transition regime, the vortex patterns of the first and second cylinders are 2P + 4S and 2P + 2S, respectively. In the galloping branch, the shear layer motion is in synchronization with the motion of the cylinder, and the maximum amplitude of 2.8D is reached by the first cylinder. The total converted power of the three cylinders increases with U*water both in the simulation and experiment. For the three cylinders, the maximum power reaches up to 85.26 W with the increase of Reynolds number. The energy conversion efficiency is stable and higher than 35% in the starting region of VIV upper branch, and the maximum value of 40.41% is obtained when Re = 40,000.
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ASSI, G. R. S., P. W. BEARMAN, and J. R. MENEGHINI. "On the wake-induced vibration of tandem circular cylinders: the vortex interaction excitation mechanism." Journal of Fluid Mechanics 661 (August 16, 2010): 365–401. http://dx.doi.org/10.1017/s0022112010003095.
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The mechanism of wake-induced vibrations (WIV) of a pair of cylinders in a tandem arrangement is investigated by experiments. A typical WIV response is characterized by a build-up of amplitude persisting to high reduced velocities; this is different from a typical vortex-induced vibration (VIV) response, which occurs in a limited resonance range. We suggest that WIV of the downstream cylinder is excited by the unsteady vortex–structure interactions between the body and the upstream wake. Coherent vortices interfering with the downstream cylinder induce fluctuations in the fluid force that are not synchronized with the motion. A favourable phase lag between the displacement and the fluid force guarantees that a positive energy transfer from the flow to the structure sustains the oscillations. If the unsteady vortices are removed from the wake of the upstream body then WIV will not be excited. An experiment performed in a steady shear flow turned out to be central to the understanding of the origin of the fluid forces acting on the downstream cylinder.
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Wong, K. W. L., J. Zhao, D. Lo Jacono, M. C. Thompson, and J. Sheridan. "Experimental investigation of flow-induced vibration of a rotating circular cylinder." Journal of Fluid Mechanics 829 (September 21, 2017): 486–511. http://dx.doi.org/10.1017/jfm.2017.540.
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While flow-induced vibration of bluff bodies has been extensively studied over the last half-century, only limited attention has been given to flow-induced vibration of elastically mounted rotating cylinders. Since recent low-Reynolds-number numerical work suggests that rotation can enhance or suppress the natural oscillatory response, the former could find applications in energy harvesting and the latter in vibration control. The present experimental investigation characterises the dynamic response and wake structure of a rotating circular cylinder undergoing vortex-induced vibration at a low mass ratio ($m^{\ast }=5.78$) over the reduced velocity range leading to strong oscillations. The experiments were conducted in a free-surface water channel with the cylinder vertically mounted and attached to a motor that provided constant rotation. Springs and an air-bearing system allow the cylinder to undertake low-damped transverse oscillations. Under cylinder rotation, the normalised frequency response was found to be comparable to that of a freely vibrating non-rotating cylinder. At reduced velocities consistent with the upper branch of a non-rotating transversely oscillating cylinder, the maximum oscillation amplitude increased with non-dimensional rotation rate up to $\unicode[STIX]{x1D6FC}\approx 2$. Beyond this, there was a sharp decrease in amplitude. Notably, this critical value corresponds approximately to the rotation rate at which vortex shedding ceases for a non-oscillating rotating cylinder. Remarkably, at $\unicode[STIX]{x1D6FC}=2$ there was approximately an 80 % increase in the peak amplitude response compared to that of a non-rotating cylinder. The observed amplitude response measured over the Reynolds-number range of ($1100\lesssim Re\lesssim 6300$) is significantly different from numerical predictions and other experimental results recorded at significantly lower Reynolds numbers.
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Jester, W., and Y. Kallinderis. "Numerical Study of Incompressible Flow About Transversely Oscillating Cylinder Pairs." Journal of Offshore Mechanics and Arctic Engineering 126, no. 4 (November 1, 2004): 310–17. http://dx.doi.org/10.1115/1.1834618.
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A numerical investigation of incompressible flow about transversely oscillating cylinder pairs is performed. Both tandem and side-by-side arrangements undergoing both flow-induced and forced transverse oscillations are considered. A second-order projection scheme is used to solve the 2-D incompressible Navier Stokes equations and a staggered approach is used to couple flow and structural response. Automatic mesh deformation and adaptation are used to handle arbitrary motion of the bodies. Comparisons with experimental results indicate that the present numerical method can capture complex interference and flow–structure interaction phenomena. Specifically, results are presented that demonstrate wake galloping effects, in which a cylinder in the wake of another experiences large flow-induced vibration over a wide range of flow velocities, and the presence of an experimentally observed secondary peak in the flow-induced vibration of rigidly connected cylinders in a tandem arrangement. An explanation of this secondary peak is provided by employing appropriate visualization of the unsteady flow. Results for forced oscillation of a pair of cylinders in a side-by-side arrangement are also presented that show the effect of phase angle on the wake structure behind the cylinder pair.
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Okajima, Atsushi, and Takahiro Kiwata. "Flow-Induced Stream-Wise Vibration of Circular Cylinders." Journal of Flow Control, Measurement & Visualization 07, no. 03 (2019): 133–51. http://dx.doi.org/10.4236/jfcmv.2019.73011.
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OKAJIMA, Atsushi, Takahiro KIWATA, Satoru YASUI, and Shigeo KIMURA. "3814 Flow-Induced Vibration of Tandem Circular Cylinders." Proceedings of the JSME annual meeting 2005.7 (2005): 193–94. http://dx.doi.org/10.1299/jsmemecjo.2005.7.0_193.
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Muhammad Ridhwaan Hassim, Mohd Azan Mohammed Sapardi, Nur Marissa Kamarul Baharin, Syed Noh Syed Abu Bakar, Muhammad Abdullah, and Khairul Affendy Mohd Nor. "CFD Modelling of Wake-Induced Vibration At Low Reynolds Number." CFD Letters 13, no. 11 (November 11, 2021): 53–64. http://dx.doi.org/10.37934/cfdl.13.11.5364.
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Flow-induced vibration is an enthralling phenomenon in the field of engineering. Numerous studies have been conducted on converting flow kinetic energy to electrical energy using the fundamental. Wake-induced vibration is one of the configurations used to optimise the generation of electricity. The results of the study on the effect of the gap between the multiple bluff bodies will provide insight into optimising the energy harvesting process. This study focuses on fluid behaviour and response behind two circular cylinders arranged in tandem when interacting with a fluid flow at low Reynolds numbers ranging from 200 to 1000. The study has been done on several gap lengths between the two cylinders, between 2D and 5D. The study was carried out numerically by using OpenFOAM. At Re = 1000, it is found that the gap length of 2.5D is optimal in terms of producing the highest lift force coefficient on the downstream circular cylinder.
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Rasani, Mohammad Rasidi, Hazim Moria, Michael Beer, and Ahmad Kamal Ariffin. "Vibration Performance of a Flow Energy Converter behind Two Side-by-Side Cylinders." Journal of Marine Science and Engineering 7, no. 12 (November 29, 2019): 435. http://dx.doi.org/10.3390/jmse7120435.
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Flow-induced vibrations of a flexible cantilever plate, placed in various positions behind two side-by-side cylinders, were computationally investigated to determine optimal location for wake-excited energy harvesters. In the present study, the cylinders of equal diameter D were fixed at center-to-center gap ratio of T / D = 1 . 7 and immersed in sub-critical flow of Reynold number R e D = 10 , 000 . A three-dimensional Navier–Stokes flow solver in an Arbitrary Lagrangian–Eulerian (ALE) description was closely coupled to a non-linear finite element structural solver that was used to model the dynamics of a composite piezoelectric plate. The cantilever plate was fixed at several positions between 0 . 5 < x / D < 1 . 5 and - 0 . 85 < y / D < 0 . 85 measured from the center gap between cylinders, and their flow-induced oscillations were compiled and analyzed. The results indicate that flexible plates located at the centerline between the cylinder pairs experience the lowest mean amplitude of oscillation. Maximum overall amplitude in oscillation is predicted when flexible plates are located in the intermediate off-center region downstream of both cylinders. Present findings indicate potential to further maximize wake-induced energy harvesting plates by exploiting their favorable positioning in the wake region behind two side-by-side cylinders.
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Zhang, C., M. J. Pettigrew, and N. W. Mureithi. "Vibration Excitation Force Measurements in a Rotated Triangular Tube Bundle Subjected to Two-Phase Cross Flow." Journal of Pressure Vessel Technology 129, no. 1 (March 31, 2006): 21–27. http://dx.doi.org/10.1115/1.2388996.
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Two-phase cross flow exists in many shell-and-tube heat exchangers. Flow-induced vibration excitation forces can cause tube motion that will result in long-term fretting-wear or fatigue. Detailed vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures over a broad range of void fraction and mass fluxes. Both the dynamic lift and drag forces were measured with strain gage instrumented cylinders. The experiments revealed somewhat unexpected but significant quasi-periodic forces in both the drag and lift directions. The periodic forces appeared well correlated along the cylinder with the drag force somewhat better correlated than the lift forces. The periodic forces are also dependent on the position of the cylinder within the bundle.
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Kumara, K. Karthik Selva, K. Aruna Devi, and L. A. Kumaraswamidhas. "SPSS: A Data Mining Tool for Analyzing the Results of Flow Induced Vibration Excitation in an Elastically Mounted Circular Cylinder at Different Interference Conditions." Applied Mechanics and Materials 592-594 (July 2014): 2086–90. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.2086.
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s: In this article, results of an analysis is investigated by using a data mining tool called ‘SPSS’, to identify the flow characteristics and response of an elastically mounted circular cylinder at different interference conditions. Numerical investigation is performed on a range of longitudinal gap ratios (2.0 ≤ L/D ≤ 4) and transverse gap ratios (2.0 ≤ T/D ≤ 4) between the cylinders arranged in tandem and staggered configuration. The effects of the interference cylinders were analyzed at specific relative positions were observed and it has been identified that the parameters, reduced velocity (U/fD) and relative positions were significantly influences the flow induced vibration excitation. Hence, in this article, an accent is laid on the efficient of ‘SPSS Tool’ for analyzing the results of flow induced vibration excitation in an elastically mounted circular cylinder at different interference conditions. From the results, it is observed that, reduced velocity must be lesser than the threshold value and also the observed that the relative positions (spacing ratios) is playing a significant role when compared to the reduced velocity. Further, the results shows that, at the fluid flow characteristics of elastically mounted circular cylinder in staggered arrangement with two interfering cylinders in upstream conditions the oscillatory amplitude ratio (A/D=0.250) is found to be minimum.
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Wang, P., C. W. Wong, Y. Zhou, and W. Xu. "Axial-flow-induced vibration of an elastic cylinder placed between two cylinders." Journal of Fluids and Structures 106 (October 2021): 103371. http://dx.doi.org/10.1016/j.jfluidstructs.2021.103371.
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Xie, Fangfang, Yue Yu, Yiannis Constantinides, Michael S. Triantafyllou, and George Em Karniadakis. "U-shaped fairings suppress vortex-induced vibrations for cylinders in cross-flow." Journal of Fluid Mechanics 782 (October 9, 2015): 300–332. http://dx.doi.org/10.1017/jfm.2015.529.
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We employ three-dimensional direct and large-eddy numerical simulations of the vibrations and flow past cylinders fitted with free-to-rotate U-shaped fairings placed in a cross-flow at Reynolds number $100\leqslant \mathit{Re}\leqslant 10\,000$. Such fairings are nearly neutrally buoyant devices fitted along the axis of long circular risers to suppress vortex-induced vibrations (VIVs). We consider three different geometric configurations: a homogeneous fairing, and two configurations (denoted A and AB) involving a gap between adjacent segments. For the latter two cases, we investigate the effect of the gap on the hydrodynamic force coefficients and the translational and rotational motions of the system. For all configurations, as the Reynolds number increases beyond 500, both the lift and drag coefficients decrease. Compared to a plain cylinder, a homogeneous fairing system (no gaps) can help reduce the drag force coefficient by 15 % for reduced velocity $U^{\ast }=4.65$, while a type A gap system can reduce the drag force coefficient by almost 50 % for reduced velocity $U^{\ast }=3.5,4.65,6$, and, correspondingly, the vibration response of the combined system, as well as the fairing rotation amplitude, are substantially reduced. For a homogeneous fairing, the cross-flow amplitude is reduced by about 80 %, whereas for fairings with a gap longer than half a cylinder diameter, VIVs are completely eliminated, resulting in additional reduction in the drag coefficient. We have related such VIV suppression or elimination to the features of the wake flow structure. We find that a gap causes the generation of strong streamwise vorticity in the gap region that interferes destructively with the vorticity generated by the fairings, hence disorganizing the formation of coherent spanwise cortical patterns. We provide visualization of the incoherent wake flow that leads to total elimination of the vibration and rotation of the fairing–cylinder system. Finally, we investigate the effect of the friction coefficient between cylinder and fairing. The effect overall is small, even when the friction coefficients of adjacent segments are different. In some cases the equilibrium positions of the fairings are rotated by a small angle on either side of the centreline, in a symmetry-breaking bifurcation, which depends strongly on Reynolds number.
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Lin, Wei, Zuo Bing Chen, Jiu Yang Yu, and Xiao Tao Zheng. "Analysis of Vortex-Induced Vibration and Heat Transfer of an Elastic Cylinder at Low Reynolds Numbers." Applied Mechanics and Materials 602-605 (August 2014): 458–64. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.458.
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The vortex-induced vibration and heat transfer of circular cylinders at low Reynolds number (Re=50~180) was numerical analyzed. The cylinder motion was modeled by a mass-spring-damper system, and the motion equation of the cylinder was solved by Newmark-β method, and then the cylinder velocity was written into the UDF of Fluent, finally, the dynamic mesh technique was used to solve the coupling between the cylinder and flow. The results including “Lock-on” and “Beat” phenomena were obtained, and the effect of mass ration on "Lock-on" was analyzed, furthermore, the influence of vortex-induced vibration on convective heat transfer was also discussed.
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Marn, Jure, and Ivan Catton. "Analysis of Flow Induced Vibration Using the Vorticity Transport Equation." Journal of Fluids Engineering 115, no. 3 (September 1, 1993): 485–92. http://dx.doi.org/10.1115/1.2910164.
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Crossflow induced vibrations are the subject of this work. The analysis is two dimensional. The governing equations for fluid motion are solved using linearized perturbation theory and coupled with the equations of motion for cylinders to yield the threshold of dynamic instability for an array of cylinders. Parametric analysis is performed to determine the lowest instability threshold for a rotated square array and correlations are developed relating the dominant parameters. The results are compared with theoretical and experimental data for similar arrays and the discrepancies are discussed.
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Bourguet, Rémi, and David Lo Jacono. "In-line flow-induced vibrations of a rotating cylinder." Journal of Fluid Mechanics 781 (September 16, 2015): 127–65. http://dx.doi.org/10.1017/jfm.2015.477.
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The flow-induced vibrations of an elastically mounted circular cylinder, free to oscillate in the direction parallel to the current and subjected to a forced rotation about its axis, are investigated by means of two- and three-dimensional numerical simulations, at a Reynolds number equal to 100 based on the cylinder diameter and inflow velocity. The cylinder is found to oscillate up to a rotation rate (ratio between the cylinder surface and inflow velocities) close to 2 (first vibration region), then the body and the flow are steady until a rotation rate close to 2.7 where a second vibration region begins. Each vibration region is characterized by a specific regime of response. In the first region, the vibration amplitude follows a bell-shaped evolution as a function of the reduced velocity (inverse of the oscillator natural frequency). The maximum vibration amplitudes, even though considerably augmented by the rotation relative to the non-rotating body case, remain lower than 0.1 cylinder diameters. Due to their trends as functions of the reduced velocity and to the fact that they develop under a condition of wake-body synchronization or lock-in, the responses of the rotating cylinder in this region are comparable to the vortex-induced vibrations previously described in the absence of rotation. The symmetry breaking due to the rotation is shown to directly impact the structure displacement and fluid force frequency contents. In the second region, the vibration amplitude tends to increase unboundedly with the reduced velocity. It may become very large, higher than 2.5 diameters in the parameter space under study. Such structural oscillations resemble the galloping responses reported for non-axisymmetric bodies. They are accompanied by a dramatic amplification of the fluid forces compared to the non-vibrating cylinder case. It is shown that body oscillation and flow unsteadiness remain synchronized and that a variety of wake topologies may be encountered in this vibration region. The low-frequency, large-amplitude responses are associated with novel asymmetric multi-vortex patterns, combining a pair and a triplet or a quartet of vortices per cycle. The flow is found to undergo three-dimensional transition in the second vibration region, with a limited influence on the system behaviour. It appears that the transition occurs for a substantially lower rotation rate than for a rigidly mounted cylinder.
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Ikegami, Y., K. Fujita, and M. Ohashi. "Nozzle jet flow-induced vibration of single circular cylinders and twin circular cylinders." Journal of Wind Engineering and Industrial Aerodynamics 49, no. 1-3 (December 1993): 207–16. http://dx.doi.org/10.1016/0167-6105(93)90016-h.
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Wang, Z. J., and Y. Zhou. "Vortex-Induced Vibration Characteristics of an Elastic Square Cylinder on Fixed Supports." Journal of Fluids Engineering 127, no. 2 (September 27, 2004): 241–49. http://dx.doi.org/10.1115/1.1881693.
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The vortex-induced structural vibration of an elastic square cylinder, on fixed supports at both ends, in a uniform cross flow was measured using fiber-optic Bragg grating sensors. The measurements are compared to those obtained for an elastic circular cylinder of the same hydraulic diameter in an effort to understand the effect of the nature (fixed or oscillating) of the flow separation point on the vortex-induced vibration. It is found that a violent vibration occurs at the third-mode resonance when the vortex-shedding frequency coincides with the third-mode natural frequency of the fluid-structure system, irrespective of the cross-sectional geometry of the cylinder. This is in distinct contrast to previous reports of flexibly supported rigid cylinders, where the first-mode vibration dominates, thus giving little information on the vibration of other modes. The resonance behavior is neither affected by the incidence angle (α) of the free stream, nor by the nature of the flow separation point. However, the vibration amplitude of the square cylinder is about twice that of the circular cylinder even though the flexural rigidity of the former is larger. This is ascribed to a difference in the nature of the flow separation point between the two types of structures. The characteristics of the effective modal damping ratios, defined as the sum of structural and fluid damping ratios, and the system natural frequencies are also investigated. The damping ratios and the system natural frequencies vary little with the reduced velocity at α=0deg, but appreciable at α⩾15deg; they further experience a sharp variation, dictated by the vortex-shedding frequency, near resonance.
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Arionfard, Hamid, and Yoshiki Nishi. "Flow-induced vibrations of two mechanically coupled pivoted circular cylinders: Characteristics of vibration." Journal of Fluids and Structures 80 (July 2018): 165–78. http://dx.doi.org/10.1016/j.jfluidstructs.2018.04.007.
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Humphries, J. A., and D. H. Walker. "Vortex-Excited Response of Large-Scale Cylinders in Sheared Flow." Journal of Offshore Mechanics and Arctic Engineering 110, no. 3 (August 1, 1988): 272–77. http://dx.doi.org/10.1115/1.3257061.
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A series of experiments were performed to measure the vortex-excited response of a 0.168-m-dia slender circular cylinder in a range of linear shear velocity profiles. Reynolds numbers of up to 2.5 × 105 were achieved. The results clearly showed that regular large-amplitude cylinder vibrations occurred well within the critical drag transition region. It was found that increasing the linear shear profile decreased the peak amplitude response but broadened the range of lock-on over which large oscillations occurred. The flow-induced vibration of the cylinder caused amplification of the mean hydrodynamic drag forces acting on the cylinder when compared with those expected for a similar rigid cylinder.
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Jiang, Zecheng, Yun Gao, Shixiao Fu, Shenglin Chai, and Chen Shi. "Effects of surface roughness on two-degree-of-freedom vortex-induced vibration of a circular cylinder in oscillatory flow." Physics of Fluids 35, no. 1 (January 2023): 015154. http://dx.doi.org/10.1063/5.0135580.
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The vortex-induced vibration (VIV) response performances of a two-degree-of-freedom circular cylinder with different surface roughnesses were numerically investigated in this work. Four typical roughnesses values of 1 × 10−4, 5 × 10−3, 1 × 10−2, and 2 × 10−2 were examined for the range of the reduced velocity ( Vr = 1–20). The VIV response characteristics including the vibration amplitude, vibration frequency, VIV trajectory, vortex shedding flowing pattern, and hydrodynamic force for different rough cylinders were systematically compared. The numerical results showed that the VIV response of roughness cylinder experiences five evolutions as Vr increases, including five typical X–Y trajectories: centrosymmetry, “M” or “W,” “dough twists” or “candy,” “∞,” and asymmetrical ∞, exhibiting three vortex shedding flow pattern: S mode, C + S mode, and SS mode (a pair of symmetric vortices along the x-axis) under certain conditions. The VIV response was sensitive to the roughness in regime IV and regime V. Furthermore, the normalized vibration frequency of the rough cylinder was an integer multiple of the oscillatory flow frequency, except for the Vr ranged from 6 to 7. The vibration frequency in in-line (IL) direction was consistent with the frequency of the oscillatory flow, which was immune to the change of roughness. Additionally, when roughness was equal to 2 × 10−2, the reduction of maximum vibration amplitude in the cross-flow direction reached 31.2%, comparing with smooth cylinder, whereas the maximum vibration amplitude in the IL direction increased only by 6.2%.
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Upnere, S. "Numerical Study of Flow-Induced Vibrations of Multiple Flexibly-Mounted Cylinders in Triangular Array." Latvian Journal of Physics and Technical Sciences 55, no. 5 (October 1, 2018): 43–53. http://dx.doi.org/10.2478/lpts-2018-0035.
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Abstract The paper presents the numerical study of vibrating multiple flexibly-mounted cylinders in a triangular rod bundle. Behavioural trends of six different clusters of oscillating rods have been analysed. The influence of neighbour cylinders on the central cylinder oscillation characteristics is analysed. Finite volume solver of open source computational fluid dynamics is used to calculate the fluid flow in the channel with the cylinder array. Built-in six degree-of-freedoms solver is utilised to simulate cylinder movement. Oscillating cylinders have two degrees-of-freedom. The obtained results are compared with numerical results available in the literature.
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Wang, Jialu, Fabo Chen, Chen Shi, and Jiuzheng Yu. "Mitigation of Vortex-Induced Vibration of Cylinders Using Cactus-Shaped Cross Sections in Subcritical Flow." Journal of Marine Science and Engineering 9, no. 3 (March 7, 2021): 292. http://dx.doi.org/10.3390/jmse9030292.
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Flexible cylinders, such as marine risers, often experience sustained vortex-induced vibrations (VIVs). Installing helical strakes on a riser is the most widely used technique to mitigate VIVs. This study was inspired by the giant Saguaro Cacti which can withstand strong wind with a shallow root system. In this study, numerical simulations of flow past a stationary cylinder of a cactus-shaped cross-section in a two-dimensional flow field at a subcritical Reynolds number of 3900 were performed. Results show that cylinders of a cactus-shaped cross-section have a lower lift coefficient without increasing drag compared to those of a circular cylinder. VIV experiments on a single flexible pipe as well as on a set of two tandem-arranged flexible pipes were conducted at different reduced velocities to investigate the effects of the streamwise spacing and wake of the cactus-like body shape on VIV mitigation. Experimental results show that the cactus-like body shape can mitigate VIV responses of the cylinder at upstream position with no cost of increased drag; however, similar to helical strakes, the efficiency of VIV mitigation for the cylinder at downstream position is reduced. Although the cactus-like body shapes tested in this study were not optimized for oscillation suppression, still this study suggests that modification of the cross-sectional shape to a well-designed cactus-like shape has potentials to be used as an alternative technology to mitigate VIV of marine risers.
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Johnstone, Andrew Dennis, and Brad Stappenbelt. "Flow-induced vibration characteristics of pivoted cylinders with splitter-plates." Australian Journal of Mechanical Engineering 14, no. 1 (November 26, 2015): 53–63. http://dx.doi.org/10.1080/14484846.2015.1093219.
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Chen, S. S. "Flow-Induced Vibration of an Array of Cylinders; Part I." Shock and Vibration Digest 23, no. 12 (December 1, 1991): 3–9. http://dx.doi.org/10.1177/058310249102301203.
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Zhao, Jisheng, Kerry Hourigan, and Mark C. Thompson. "Dynamic response of elliptical cylinders undergoing transverse flow-induced vibration." Journal of Fluids and Structures 89 (August 2019): 123–31. http://dx.doi.org/10.1016/j.jfluidstructs.2019.01.011.
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Obasaju, E. D., R. Ermshaus, and E. Naudascher. "Further results on the flow-induced streamwise vibration of cylinders." Journal of Fluids and Structures 6, no. 1 (January 1992): 51–66. http://dx.doi.org/10.1016/0889-9746(92)90055-8.
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Wang, Jia-song, Dixia Fan, and Ke Lin. "A review on flow-induced vibration of offshore circular cylinders." Journal of Hydrodynamics 32, no. 3 (June 2020): 415–40. http://dx.doi.org/10.1007/s42241-020-0032-2.
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Piran, Farid, Hassan Karampour, and Peter Woodfield. "Numerical Simulation of Cross-Flow Vortex-Induced Vibration of Hexagonal Cylinders with Face and Corner Orientations at Low Reynolds Number." Journal of Marine Science and Engineering 8, no. 6 (May 28, 2020): 387. http://dx.doi.org/10.3390/jmse8060387.
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Vortex-induced vibrations (VIV) of hexagonal cylinders at Reynolds number of 1000 and mass ratio of 2 are studied numerically. In the numerical model, the Navier–Stokes equations are solved using finite volume method, and the fluid-structure interaction (FSI) is modelled using Arbitrary Lagrangian Eulerian (ALE) Scheme. The numerical model accounts for the cross-flow vibration of the cylinders, and is validated against published experimental and numerical results. In order to account for different angles of attack, the hexagonal cylinders are studied in the corner and face orientations. The results are compared with the published results of circular and square cylinders. Current results show that within the studied range of reduced velocities (up to 20), unlike circular and square cylinders, no lock-in response is observed in the hexagonal cylinders. The maximum normalized VIV amplitudes of the hexagonal cylinders are 0.45, and are significantly lower than those of circular and square cylinders. Vortex shedding regimes of the corner-oriented hexagons are mostly irregular. However, in the face-oriented hexagons, the shedding modes are more similar to the typical P + S and 2P modes.
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Bourguet, Rémi, and David Lo Jacono. "Flow-induced vibrations of a rotating cylinder." Journal of Fluid Mechanics 740 (February 6, 2014): 342–80. http://dx.doi.org/10.1017/jfm.2013.665.
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AbstractThe flow-induced vibrations of a circular cylinder, free to oscillate in the cross-flow direction and subjected to a forced rotation about its axis, are analysed by means of two- and three-dimensional numerical simulations. The impact of the symmetry breaking caused by the forced rotation on the vortex-induced vibration (VIV) mechanisms is investigated for a Reynolds number equal to $100$, based on the cylinder diameter and inflow velocity. The cylinder is found to oscillate freely up to a rotation rate (ratio between the cylinder surface and inflow velocities) close to $4$. Under forced rotation, the vibration amplitude exhibits a bell-shaped evolution as a function of the reduced velocity (inverse of the oscillator natural frequency) and reaches $1.9$ diameters, i.e. three times the maximum amplitude in the non-rotating case. The free vibrations of the rotating cylinder occur under a condition of wake–body synchronization similar to the lock-in condition driving non-rotating cylinder VIV. The largest vibration amplitudes are associated with a novel asymmetric wake pattern composed of a triplet of vortices and a single vortex shed per cycle, the ${\rm T} + {\rm S}$ pattern. In the low-frequency vibration regime, the flow exhibits another new topology, the U pattern, characterized by a transverse undulation of the spanwise vorticity layers without vortex detachment; consequently, free oscillations of the rotating cylinder may also develop in the absence of vortex shedding. The symmetry breaking due to the rotation is shown to directly impact the selection of the higher harmonics appearing in the fluid force spectra. The rotation also influences the mechanism of phasing between the force and the structural response.
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Callander, Stephen John. "Flow‐Induced Vibrations of Rectangular Cylinders." Journal of Hydraulic Engineering 115, no. 10 (October 1989): 1316–31. http://dx.doi.org/10.1061/(asce)0733-9429(1989)115:10(1316).
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Yao, W., and R. K. Jaiman. "Feedback control of unstable flow and vortex-induced vibration using the eigensystem realization algorithm." Journal of Fluid Mechanics 827 (August 22, 2017): 394–414. http://dx.doi.org/10.1017/jfm.2017.470.
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We present an active feedback blowing and suction (AFBS) procedure via model reduction for unsteady wake flow and the vortex-induced vibration (VIV) of circular cylinders. The reduced-order model (ROM) for the AFBS procedure is developed by the eigensystem realization algorithm (ERA), which provides a low-order representation of the unsteady flow dynamics in the neighbourhood of the equilibrium steady state. The actuation is considered via vertical suction and a blowing jet at the porous surface of a circular cylinder with a body-mounted force sensor. While the optimal gain is obtained using a linear quadratic regulator (LQR), Kalman filtering is employed to estimate the approximate state vector. The feedback control system shifts the unstable eigenvalues of the wake flow and the VIV system to the left half-complex-plane, and subsequently results in suppression of the vortex street and the VIV in elastically mounted structures. The resulting controller designed by a linear low-order approximation is able to suppress the nonlinear saturated state of wake vortex shedding from the circular cylinder. A systematic linear ROM-based stability analysis is performed to understand the eigenvalue distribution for the flow past stationary and elastically mounted circular cylinders. The results from the ROM analysis are consistent with those obtained from full nonlinear fluid–structure interaction simulations, thereby confirming the validity of the proposed ROM-based AFBS procedure. A sensitivity study on the number of suction/blowing actuators, the angular arrangement of actuators and the combined versus independent control architectures has been performed for the flow past a stationary circular cylinder. Overall, the proposed control concept based on the ERA-based ROM and the LQR algorithm is found to be effective in suppressing the vortex street and the VIV for a range of reduced velocities and mass ratios.