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Showing papers on "Vortex-induced vibration published in 2012"


Journal ArticleDOI
TL;DR: A review of the progress made during the past decade on vortex-induced vibration (VIV) of long slender cylindrical structures is given in this article, where a brief outline is given of numerical methods used in predicting the response of a long slender cylinder undergoing VIV.

294 citations


Journal ArticleDOI
TL;DR: In this article, an advanced model for predicting a two-dimensional coupled cross-flow/in-line VIV of a flexibly mounted circular cylinder in a uniform flow is proposed and validated.

157 citations


Journal ArticleDOI
TL;DR: In this article, the influence of angle of attack of a square section cylinder on the cylinder's flow-induced vibration was examined, where the direction of the vibration is transverse to the oncoming flow.
Abstract: This study examines the influence of angle of attack of a square section cylinder on the cylinder’s flow-induced vibration, where the direction of the vibration is transverse to the oncoming flow. Our experiments, which traversed the velocity–angle of attack parameter space in considerable breadth and depth, show that a low-mass ratio body can undergo combinations of both vortex-induced vibration and galloping. When the body has an angle of attack that makes it symmetric to the flow, such as when it assumes the square or diamond orientation, the two mechanisms remain independent. However, when symmetry is lost we find a mixed mode response with a new branch of vortex-induced oscillations that exceeds the amplitudes resulting from the two phenomena independently. The oscillations of this higher branch have amplitudes larger than the ‘upper branch’ of vortex-induced vibrations and at half the frequency. For velocities above this resonant region, the frequency splits into two diverging branches. Analysis of the amplitude response reveals that the transition between galloping and vortex-induced vibrations occurs over a narrow range of angle of incidence. Despite the rich set of states found in the parameter space the vortex shedding modes remain very similar to those found previously in vortex-induced vibration.

156 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of some influencing parameters, like the mass ratio m∗ or the mechanical damping ζ in the energy conversion factor is investigated, and the analysis reveals that the maximum efficiency of a circular cylinder is principally influenced by the mass-damping parameter m ∗ζ.

151 citations


Journal ArticleDOI
TL;DR: The excellent agreement between the present results and the reference data from experiments and other simulations demonstrates the accuracy, simplicity, and efficiency of the new method and its applicability in a wide range of complicated fluid-structure interaction problems.

133 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate energy harvesting from vortex-induced vibrations of a freely moving rigid circular cylinder with a piezoelectric transducer attached to its transverse degree of freedom and determine the power levels that can be generated from these vibrations and variations of these levels with the freestream velocity.
Abstract: We investigate energy harvesting from vortex-induced vibrations of a freely moving rigid circular cylinder with a piezoelectric transducer attached to its transverse degree of freedom. The power levels that can be generated from these vibrations and variations of these levels with the freestream velocity are determined. A mathematical model that accounts for the coupled lift force, cylinder motion, and harvested voltage is presented. Linear analysis is performed to determine the effect of the electrical load resistance of the transducer on the natural frequency of the cylinder and the onset of synchronization (the shedding frequency is equal to the cylinder oscillating frequency) region. The impact of the nonlinearities on the cylinder response and harvested energy is investigated. The results show that the load resistance shifts the onset of synchronization to higher freestream velocities. For two different system parameters, the results show that the nonlinearities result in a hardening behavior for some values of the load resistance.

106 citations


Journal ArticleDOI
TL;DR: In this paper, the authors presented experimental results of flow around a circular cylinder with moving surface boundary layer control (MSBC) and showed that the use of the flow control results in a mean drag reduction at U c / U = 5 of almost 60% compared to the plain cylinder.

100 citations


Journal ArticleDOI
TL;DR: In this paper, the internal two-phase flow induced fluctuating forces on pipe bends were studied with a 52.5mm I.D., 90° elbow to investigate the impact of liquid slugs on the elbow.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the two-degree-of-freedom Vortex-Induced Vibration (VIV) of four rigidly coupled circular cylinders in a square configuration and showed that the approaching angle has significant effects on the response of the four-cylinder system.

63 citations


Journal ArticleDOI
TL;DR: In this article, the effect of hydrofoil trailing edge shape on the wake dynamic and flow induced vibration is investigated at high Reynolds number, Re ¼0.5 � 10 6 −2.9 x 10 6.

60 citations


Journal ArticleDOI
TL;DR: In this article, experimental and numerical investigations are conducted using rigid and flexible valve head supports to clarify the mechanisms of valve head vibrations that are caused by unsteady flows around the valve.

Journal ArticleDOI
TL;DR: In this paper, the frequency components are multiples of the frequency of the oscillatory flow except at a few reduced velocities and the change from one vibration mode to another is regular and periodic.

Journal ArticleDOI
TL;DR: In this article, the authors presented a model formulation that can be used for analyzing the three-dimensional vibration behaviors of an inclined extensible steel catenary riser (SCR).

Journal ArticleDOI
TL;DR: In this paper, the effects of gap ratio (G / D ) between the two cylinders and the angular position of the small cylinder relative to the large one on the vibration amplitude and frequency were investigated numerically.

Journal ArticleDOI
TL;DR: In this paper, a nonlinear model is developed for the vibration of a single-walled carbon nanotube (SWCNT) based on Eringen's nonlocal elasticity theory.

Journal ArticleDOI
TL;DR: In this article, a method using passive turbulence control (PTC) consisting of selectively located roughness on the cylinder surface with thickness about equal to the boundary layer thickness is formulated and tested experimentally.
Abstract: A passive control means to suppress flow-induced motions (FIM) of a rigid circular cylinder in the TrSL3, high-lift, flow regime is formulated and tested experimentally. The developed method uses passive turbulence control (PTC) consisting of selectively located roughness on the cylinder surface with thickness about equal to the boundary layer thickness. The map of “PTC-to-FIM,” developed in previous work, revealed robust zones of weak suppression, strong suppression, hard galloping, and soft galloping. PTC has been used successfully to enhance FIM for hydrokinetic energy harnessing using the VIVACE Converter. PTC also revealed the potential to suppress FIM to various levels. The map is flow-direction dependent. In this paper, the “PTC-to-FIM” map is used to guide development of FIM suppression devices that are flow-direction independent and hardly affect cylinder geometry. Experiments are conducted in the Low Turbulence Free Surface Water Channel of the University of Michigan on a rigid, horizontal, circular cylinder, suspended on springs. Amplitude and frequency measurements and broad field-of-view visualization reveal complex flow structures and their relation to suppression. Several PTC designs are tested to understand the effect of PTC roughness, location, coverage, and configuration. Gradual modification of PTC parameters, leads to improved suppression and evolution of a design reducing the VIV synchronization range. Over a wide range of high reduced velocities, VIV is fully suppressed. The maximum amplitude occurring near the system’s natural frequency is reduced by about 63% compared to the maximum amplitude of the smooth cylinder.

Journal ArticleDOI
TL;DR: In this paper, an experimental study about vortex induced vibrations on a rigid suspended cylinder characterized by high value of mass ratio (m) and tested at high Reynolds number condition is presented.

Journal ArticleDOI
TL;DR: Based on the nonlocal continuum theory, transverse vibration of a single-walled carbon nanotube (SWCNT) conveying fluid with immovable support conditions is investigated in this article.

Journal ArticleDOI
TL;DR: In this paper, a time-domain approach for predicting dynamic characteristics and vortex-induced vibration (VIV) response of deepwater risers is proposed based on finite element simulation combined with a hydrodynamic model.

Journal ArticleDOI
TL;DR: In this article, the effects of a tripped turbulent boundary layer on the wake characteristics are analyzed and compared with the condition of a natural turbulent transition, where the foil surface is hydraulically smooth and a fully effective boundary layer tripping at the leading edge achieved with the help of a distributed roughness.
Abstract: Experiments on vortex shedding from a blunt trailing edge symmetric hydrofoil operating at zero angle of attack in a uniform high speed flow, Re-h = 16.1 . 10(3) - 96.6 . 10(3), where the reference length h is the trailing edge thickness, are reported. The effects of a tripped turbulent boundary layer on the wake characteristics are analyzed and compared with the condition of a natural turbulent transition. The foil surface is hydraulically smooth and a fully effective boundary layer tripping at the leading edge is achieved with the help of a distributed roughness. The vortex shedding process is found to be strongly influenced by the boundary layer development: the tripped turbulent transition promotes the re-establishment of organized vortex shedding. In the context of the tripped transition and in comparison with the natural one, significant increases in the vortex span-wise organization, the vortex-induced hydrofoil vibration, the wake velocity fluctuations, and the vortex strength are revealed. Although the vortex shedding frequency is decreased, a modified Strouhal number based on the wake width at the end of the vortex formation region is constant and evidences the similarity of the wakes in terms of spatial distribution for the two considered boundary layer transition processes. [DOI: 10.1115/1.4006700]

Proceedings ArticleDOI
01 Jul 2012
TL;DR: In this article, the authors explored the Reynolds number dependence of the Vortex-Induced Vibration (VIV) of flexible marine risers and revealed the trends that exist between the Strouhal number and Reynolds number.
Abstract: This paper explores the Reynolds number dependence of the Vortex-Induced Vibration (VIV) of flexible marine risers Emphasis is placed on revealing the trends that exist between the Strouhal number and the Reynolds number and between the dimensionless amplitude (A/D) and Reynolds number Data is drawn from recent towing tank experiments which used flexible cylinders of three different diameters The 38m long pipes were exposed to uniform and sheared currents The Reynolds number range extended from approximately 5,000 to 220,000 — well into the critical regime — with the larger diameter pipes responding in up to the 13th mode and the smaller diameter pipe responding well above the 20th mode The results and trends from this set of experiments are compared to previous results from laboratory and field experimentsCopyright © 2012 by ASME

Dissertation
01 Jan 2012
TL;DR: In this paper, the authors investigated the flow characteristic and vortex induced vibration (VIV) of a cylindrical structure due to the incompressible laminar and turbulent flow at Reynolds number 40, 100, 200 and 1000.
Abstract: This thesis presents the investigation of the flow characteristic and vortex induced vibration (VIV) of a cylindrical structure due to the incompressible laminar and turbulent flow at Reynolds number 40, 100, 200 and 1000. The simulations were performed by solving the steady and transient (unsteady) 2D Navier-Stokes equation. For Reynolds number 40, the simulations were set as a steady and laminar flow and the SIMPLE and QUICK were used as the pressure-velocity coupling scheme and momentum spatial discretization respectively. Moreover, the transient turbulent flow was set for Re 100, 200 and 1000 and SIMPLE and LES (large Eddies Simulation) were selected as the pressure-velocity coupling solution and the turbulent model respectively. The drag and lift coefficient (Cd and Cl) were obtained and verified to the previous studies and showed a good agreement. Whilst the vibration frequency (fvib), the vortex shedding frequency (fv), the Strouhal number (St) and the amplitude of the vibration (A) were also measured.

Journal ArticleDOI
Licheng Sun1, Zhi Zong1, J. Dong, Guohai Dong1, C.F. Liu1 
TL;DR: In this paper, a stripwise discrete vortex method (SDVM) is employed to calculate the vortex-induced vibration (VIV) of each strip, and the finite volume method and increment method are used to compute the 3D dynamics of the flexible riser.


DOI
01 Jan 2012
TL;DR: In this article, the effect of a hydrofoil trailing edge shape on the wake dynamic and its interaction with the mechanical structure is investigated in a high speed cavitation tunnel at zero angle of attack and high Reynolds numbers.
Abstract: In the present study, the effect of a hydrofoil trailing edge shape on the wake dynamic and its interaction with the mechanical structure is investigated. This would help better describe the physical reasons for vibration reduction when using oblique and Donaldson trailing edges in comparison to a truncated trailing edge and subsequently allow its further optimization. Thus, hydrofoils with oblique and Donaldson trailing edges are tested in a high-speed cavitation tunnel at zero angle of attack and high Reynolds numbers, ReL = 5·105 – 3·106. The truncated trailing edge hydrofoil is selected as reference. A velocity survey is performed via Laser Doppler Velocimetery, LDV, and Particle Image Velocimetry, PIV. Proper-Orthogonal-Decomposition, POD, is used to extract coherent structures from PIV data. In addition, flow induced vibration measurements and high-speed visualizations are performed. Finally, the effects of a tripped boundary layer transition on the wake are investigated and compared with the natural boundary layer transition. Vortex-induced vibration is found to decrease significantly for oblique and Donaldson trailing edges in comparison to the truncated case, specially under lock-off condition. However, minimum vibration corresponds to the Donaldson trailing edge. The high-speed videos clearly show that for three tested hydrofoils the alternate vortices clearly detach from suction and pressure sides of the trailing edge. However, for the oblique and Donaldson trailing edges the location of the lower vortex detachment is obviously shifted upstream with respect to the upper one. As a result, when the upper vortex rolls up, it coincides with the passage of the lower vortex, leading to their collision. This strong interaction leads to a redistribution of the vorticity, which does not concentrate within the core of Karman vortices any more. However, the spatial phase shift between the separation point of the upper and the lower vortices is different in the case of oblique and Donaldson trailing edges due to the being free the separation point on the Donaldson curve. LDV phase-locked averaging under lock-in condition is performed for truncated, oblique and Donaldson trailing edges. The truncated trailing edge exhibits a symmetric wake. However, in the case of the oblique and Donaldson trailing edges, an asymmetric thickening of the downward near wake is observed. The stream wise velocity fluctuation shows two peaks of different amplitudes. In the case of the truncated trailing edge, the upper and lower vortices have the same core diameter, contrary to the oblique trailing edge, where a larger vortex core diameter is found for the lower vortex. In the case of Donaldson trailing edge, the LDV phase-locked averaging is performed for the tripped transition where the vibration amplitude is high enough to perform the phase-locked average. The measurements show the passage of one vortex after the collision in the near wake contrary to the oblique one. However, the passage of two vortices corresponding to the upper and lower vortex is found far from the Donaldson trailing edge. LDV measurements show that the collision of the vortices for the oblique trailing edge, observed under lock-in conditions, also prevails for the lock-off condition in the case of oblique and Donaldson trailing edges. The velocity profile comparison at the vortex formation length for three trailing edges shows that in the case of the Donaldson trailing edge, the wake width increases significantly in comparison to two other trailing edges. Moreover, the minimum stream wise and transverse velocity fluctuation profiles obtained for the three trailing edges correspond to the Donaldson trailing edge. The strong similarity of results obtained for lock-in and lock-off conditions indicates that the collision between upper and lower vortices, clearly observed under lock-in, also occurs for lock-off condition. A thicker boundary layer with laminar-to-turbulent transition occurring further upstream is observed for the pressure side of the Donaldson trailing edge in comparison with the suction side. In contrast to the truncated trailing edge, both sides have a similar boundary layer structure and a similar transition location. Moreover, a thicker boundary layer is found for the Donaldson trailing edge in comparison to the truncated case. The collision between upper and lower vortices is also observed in the case of a tripped transition. However, the vortices are shed with a larger core diameter, greater strength, and lower frequency than for the natural transition. These investigations let us believe that the collision between upper and lower vortices and the resulting vorticity redistribution is the main reason for the vibration reduction obtained with oblique and Donaldson trailing edges. This result opens the way for more effective hydrofoil geometry optimization for further reduction of flow induced vibration.

Patent
04 Jul 2012
TL;DR: In this article, a marine riser with an air-guide-sensor and a flow-distorting rib is used to inhibit the vortex-induced vibration of the riser.
Abstract: The invention relates to a vibration inhibiting method and a vibration inhibiting device capable of effectively inhibiting vortex-induced vibration of a marine riser. The vibration inhibiting device is provided with the riser, an air guide sleeve on the riser, and a flow disturbing device which is fixed on the air guide sleeve, and is characterized in that the flow disturbing device is a flow disturbing rib which is formed by a plurality of end-to-end crescent-shaped flow disturbing ribs; and the flow disturbing rib is arranged on the outer surface of the air guide sleeve in the form of beingwinded by a spiral line, and the screw pitch of the flow distributing rib is 5 to 15 times of the outside diameter of the riser. The vibration inhibiting method comprises the following steps: firstly, the air guide sleeve which is enwrapped and fixed on the outer surface of the riser is prepared according to the outside diameter of the riser required to be protected; secondly, one flow disturbingrib or a plurality of flow disturbing ribs which are manufactured are fixed on the outer surface of the air guide sleeve in advance according to the screw pitch or the position of the spiral line which is predefined and marked on the outer surface of the air guide sleeve; and thirdly, the air guide sleeve provided with the flow disturbing rib is arranged on the outer surface of the riser. Therefore, the vibration inhibiting method and the vibration inhibiting device can effectively inhibit the vortex-induced vibration of the riser; the weight of the device can be reduced from 30 percent to 60percent; and the construction cost can be greatly reduced.


Journal ArticleDOI
TL;DR: In this article, the hysteresis effect on the vortex induced vibration (VIV) on a circular cylinder is investigated by the numerical solution of the two-dimensional Reynolds averaged Navier-Stokes equations.
Abstract: The hysteresis effect on the vortex induced vibration (VIV) on a circular cylinder is investigated by the numerical solution of the two-dimensional Reynolds averaged Navier-Stokes equations. An upwind and total variation diminishing (TVD) conservative scheme is used to solve the governing equations written in curvilinear coordinates and the k-e turbulence model is used to simulate the turbulent flow in the wake of the body. The cylinder is supported by a spring and a damper and free to vibrate in the transverse direction. In previous work, numerical results for the amplitude of oscillation and vortex shedding frequency were compared to experimental data obtained from the literature to validate the code for VIV simulations. In the present work, results of practical interest are presented for the power absorbed by the system, phase angle, amplitude, frequency, and lift coefficient. The numerical results indicate that the hysteresis effect is observed only when the frequency of vortex shedding gets closer to the natural frequency of the structure in air.

Journal ArticleDOI
TL;DR: In this article, experiments on the three types of VIVs are carried out using a water tunnel to investigate influences of the mass ratio MR and the damping ratio ζ on the oscillation response.

Journal ArticleDOI
TL;DR: In this article, the fluid dynamics of rolling wheels at Reynolds number (where is the Reynolds number based on the wheel diameter), with the objective of characterizing the various regimes of steady and unsteady motion.
Abstract: We study the fluid dynamics of rolling wheels at Reynolds number (where is the Reynolds number based on the wheel diameter), with the objective of characterizing the various regimes of steady and unsteady motion. Regardless of the Reynolds number, the flow is found to separate approximately upstream of the apex of the wheel, where a saddle point in the pseudo-streamtrace pattern is observed. Under the flow conditions here essayed, the drag coefficient steadily decreases with , and the lift coefficient remains strictly positive. The positive lift provided by the rolling wheel is associated with the presence of a strong (positive) peak of the static pressure in the upstream proximity of the contact point with the ground, which we interpret as the result of the impingement of flow particles entrained in the boundary layer that develops on the front part of the wheel. Steady laminar flow is observed up to , which is characterized by a three-dimensional wake whose length increases with the Reynolds number. Unsteadiness is first observed at , under which conditions the flow retains planar symmetry, and is characterized by the quasi-periodic shedding of hairpin vortices. Transition to three-dimensional flow happens at , in which case a sinuous mode of instability in the wheel wake is established, which modulates the shedding of the hairpins, and which causes the onset of a non-zero side force. At the highest Reynolds number considered here () the wake exhibits some characters of turbulence, with wide-band frequency spectra, and its topology entirely changes, becoming split into two parts, and being much shortened compared to the lower- cases. Despite the limitation of the study to low Reynolds numbers we find that, once significant three-dimensionality and scale separation are established in the wheel wake, the nature of the flow becomes qualitatively similar to fully developed turbulent flow. In perspective, this observation opens interesting avenues for the prediction of unsteady flow around rotating tyres at moderate computational cost.