Cross-Flow Past an Oscillating Circular Cylinder: Synchronization Phenomena in the Near Wake

Krishnamoorthy, S.; Price, S.J.; Paı̈doussis, M.P.

doi:10.1006/jfls.2001.0382

Cited by 52 publications

(31 citation statements)

References 29 publications

(46 reference statements)

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“…Griffin & Ramberg (1974) observed that at Re = 190, as the forced oscillation amplitude increased from zero to 0.5d, the lock-on occurred, resulting in a decrease in the vortex formation length by 1d. A similar observation was made by Krishnamoorthy, Price & Paidoussis (2001) at Re ≈ 1500. Griffin & Ramberg further noted an inverse relationship between the vortex strength and the vortex formation length.…”

Section: Streamwise Velocity and Vortex Formation Lengthsupporting

confidence: 85%

Turbulent wake of an inclined cylinder with water running

Alam

Zhou

2007

J. Fluid Mech.

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This paper presents the results of an experimental study of fluid dynamics around an inclined circular cylinder with and without water running over its surface, covering water rivulet formation, fluid forces on the cylinder, near wake and their interrelationships. The cylinder inclination angle (α) with respect to incident flow was between 55 • and 80 • . It has been found that water running over the cylinder surface may behave quite differently, depending on the Reynolds number (Re), and subsequently impact greatly upon the fluid dynamics around the cylinder. As such, five flow categories are classified. Category A: one water rivulet was observed, irrespective of α, at the leading stagnation point at a small Re. Category B: the rivulet splits into two, symmetrically arranged about the leading stagnation line, once Re exceeds a critical value that depends on α. The two rivulets may further switch back to one, and vice versa. Category C: two symmetrical straight rivulets occur. Category D: the two rivulets shift towards the flow separation line with increasing Re and oscillate circumferentially. The oscillation reaches significant amplitude when the rivulets occur at about 70 • from the leading stagnation point. This increased amplitude is coupled with a rapid climb in the mean and fluctuating drag and lift, by a factor of near 5 for the fluctuating lift at α = 80 • . Meanwhile, the flow structure exhibits a marked variation. For example, Strouhal number and vortex formation length decrease, along with an increase in spanwise vorticity concentration, velocity deficit, and coherence between vortex shedding and fluctuating lift. All these observations point to the occurrence of a 'lock-in' phenomenon, i.e. the rivulet oscillation synchronizing with flow separation. A rivulet-vortex-induced instability is proposed to be responsible for the well reported rain-wind-induced vibration associated with the stay cables of cablestayed bridges. Category E: the two rivulets shift further downstream just beyond the separation line; the shear layers behind the rivulets become highly turbulent, resulting in weakened vortex shedding, flow fluctuating velocities and fluctuating fluid forces. Based on the equilibrium of water rivulet weight, aerodynamic pressure and friction force between fluid and surface, an analysis is developed to predict the rivulet position on the cylinder, which agrees well with measurements.

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Section: Streamwise Velocity and Vortex Formation Lengthsupporting

confidence: 85%

Turbulent wake of an inclined cylinder with water running

Alam

Zhou

2007

J. Fluid Mech.

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“…24 For example, for flow over a single oscillating cylinder, the computational results at various forcing frequencies were shown in Zheng and Zhang, 3 where both frequency lock-in and non-lock-in cases were identified using time histories and power spectra of lift and drag, and good agreements were achieved in comparison to literature data. 5,6,9,18 These examples have provided sufficient validations for the computational scheme used in our study.…”

Section: Numerical Simulationmentioning

confidence: 88%

“…[4][5][6] Detailed mechanisms of this problem have also been reviewed. 7 Furthermore, a new development in the numerical schemes for computational studies of flow over a two-dimensional oscillating cylinder has been recently reported.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear spacing and frequency effects of an oscillating cylinder in the wake of a stationary cylinder

Yang

Zheng

2010

Physics of Fluids

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A numerical study of the laminar necklace vortex system and its effect on the wake for a circular cylinder Phys. Fluids 24, 073602 (2012) Nonlinear responses to a transversely oscillating cylinder in the wake of a stationary upstream cylinder are studied theoretically by using an immersed-boundary method at Re= 100. Response states are investigated in the three flow regimes for a tandem-cylinder system: the "vortex suppression" regime, the critical spacing regime, and the "vortex formation" regime. When the downstream cylinder is forced to oscillate at a fixed frequency and amplitude, the response state of flow around the two cylinders varies with different spacing between the two cylinders, while in the same flow regime, the response state can change with the oscillating frequency and amplitude of the downstream cylinder. Based on velocity phase portraits, each of the nonlinear response states can be categorized into one of the three states in the order of increasing chaotic levels: lock-in, transitional, or quasiperiodic. These states can also be correlated with velocity spectral behaviors. The discussions are conducted using near-wake velocity phase portraits, spectral analyses, and related vorticity fields. A general trend in the bifurcation diagrams of frequency spacing shows the smaller the spacing, frequency, or amplitude, the less chaotic the response state of the system and more likely the downstream and upstream wakes are in the same response state. The system is not locked-in in any case when the spacing between the cylinders is larger than the critical spacing. The near-wake velocity spectral behaviors correspond to the nonlinear response states, with narrow-banded peaks shown at the oscillation frequency and its harmonics in the lock-in cases. High frequency harmonic peaks, caused by interactions between the upstream wake and the downstream oscillating cylinder, are reduced in the near-wake velocity spectra of the upstream cylinder when the spacing increases.

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“…Krishnamoorthy et al [8] investigated the wake patterns of an oscillating cylinder at Reynolds number of 1,500. They varied the frequency of oscillation from one-third to three times the natural shedding frequency with a nondimensional amplitude of 0.22.…”

Section: Mathematical Problems In Engineeringmentioning

confidence: 99%

Higher-Order Spectral Analysis to Identify Quadratic Nonlinearities in Fluid-Structure Interaction

Akhtar

Elyyan

2018

Mathematical Problems in Engineering

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Hydrodynamic forces on a structure are the manifestation of fluid-structure interaction. Since this interaction is nonlinear, these forces consist of various frequencies: fundamental, harmonics, excitation, sum, and difference of these frequencies. To analyze this phenomenon, we perform numerical simulations of the flow past stationary and oscillating cylinders at low Reynolds numbers. We compute the pressure, integrate it over the surface, and obtain the lift and drag coefficients for the two configurations: stationary and transversely oscillating cylinders. Higher-order spectral analysis is performed to investigate the nonlinear interaction between the forces. We confirmed and investigated the quadratic coupling between the lift and drag coefficients and their phase relationship. We identify additional frequencies and their corresponding energy present in the flow field that appear as the manifestation of quadratic nonlinear interaction.

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Cross-Flow Past an Oscillating Circular Cylinder: Synchronization Phenomena in the Near Wake

Cited by 52 publications

References 29 publications

Turbulent wake of an inclined cylinder with water running

Turbulent wake of an inclined cylinder with water running

Nonlinear spacing and frequency effects of an oscillating cylinder in the wake of a stationary cylinder

Higher-Order Spectral Analysis to Identify Quadratic Nonlinearities in Fluid-Structure Interaction

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