Flow-induced vibrations of a square prism free to oscillate in the cross-flow and inline directions

Carlson, Daniel W.; Currier, Todd; Modarres‐Sadeghi, Yahya

doi:10.1017/jfm.2021.352

Cited by 18 publications

(11 citation statements)

References 32 publications

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“…Figure 10 represents the frequency contents of the inline force coefficients for the sample cases of a single DOF cylinder (figure 10 a ) and three eigenfrequencies of and 2.1 (figure 10 b – d ). For the single DOF system, the inline force coefficients follow a trend that is in agreement with previous VIV studies, for which the second harmonic frequencies, with values twice the natural frequency of the system, are observed as the dominant frequency, with small contributions from the first harmonic frequencies (Carlson, Currier & Modarres-Sadeghi 2021). When the cylinder is given the second DOF, the frequency content still exhibits the first and second harmonic contributions of each eigenfrequency.…”

Section: Resultssupporting

confidence: 91%

“…However, in general, any asymmetry of the wake can lead to frequency contents at similar values of those in the lift forces and their corresponding second harmonics, as those considered here in (Carlson et al. 2021). For a small angle between the flow velocity and the relative velocity, , where is the dimensionless velocity of the cylinder in the crossflow direction.…”

Section: Resultssupporting

confidence: 64%

“…It is worth noting that ideally, for a symmetric wake of the cylinder, one would expect the drag force frequency content to include only frequencies twice those observed in the lift direction. However, in general, any asymmetry of the wake can lead to frequency contents at similar values of those in the lift forces and their corresponding second harmonics, as those considered here in (4.6) (Carlson et al 2021).…”

Section: Flow Forcesmentioning

confidence: 56%

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Vortex-induced vibration of a two degree-of-freedom flexibly mounted circular cylinder in the crossflow direction

et al. 2022

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Vortex-induced vibration (VIV) of a two degree-of-freedom (DOF) circular cylinder, placed in the test section of a recirculating water tunnel and free to oscillate in its first two vibrational modes in the crossflow direction, is studied experimentally. The dynamic response of the cylinder is studied for a reduced velocity range of $U^*=4\unicode{x2013}30$ for eigenfrequency ratios in the range of 1.3–3.0. For the two DOF system, while the onset of the VIV response followed a similar lock-in region as those observed for a classical VIV response of a single DOF system, by increasing the reduced velocity a secondary lock-in region was observed over which the oscillations of the cylinder were locked into the system's second mode. In addition, there existed an intermediate range of reduced velocity over which the VIV response consisted of oscillations at a combination of the first two natural modes of the system. As the eigenfrequency ratio between the first two modes increased, the secondary lock-in range was extended to higher reduced velocities and the reduced velocity range over which multi-modal oscillations were observed was decreased. A full map of vortex dynamics in the wake of the cylinder was developed qualitatively and quantitatively using hydrogen bubble flow visualization and time-resolved volumetric particle tracking velocimetry techniques, respectively. A Q-criterion analysis revealed the existence of highly three-dimensional vortex structures in the wake of the cylinder. The spatiotemporal mode analysis using the proper orthogonal decomposition technique revealed strong coupling between the vortex shedding modes in the wake of the cylinder and the structural vibration modes.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 64%

Section: Flow Forcesmentioning

confidence: 56%

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Vortex-induced vibration of a two degree-of-freedom flexibly mounted circular cylinder in the crossflow direction

et al. 2022

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“…VIV has also been studied for non-circular cross-sections, such as a square prism or a triangular prism, in which cases, besides VIV, galloping response has been observed, due to the non-zero mean lift forces that act on the structure (e.g. Nemes et al 2012;Zhao et al 2014;Seyed-Aghazadeh, Carlson & Modarres-Sadeghi 2017;Carlson, Currier & Modarres-Sadeghi 2021). Studies on VIV have been extended to cases of flexible continuous structures placed in flow, due to the fact that in real-life applications, VIV is observed in long offshore structures such as risers in oil platforms or mooring lines of floating wind turbines.…”

Section: Introductionmentioning

confidence: 99%

“…2012; Zhao et al. 2014; Seyed-Aghazadeh, Carlson & Modarres-Sadeghi 2017; Carlson, Currier & Modarres-Sadeghi 2021). Studies on VIV have been extended to cases of flexible continuous structures placed in flow, due to the fact that in real-life applications, VIV is observed in long offshore structures such as risers in oil platforms or mooring lines of floating wind turbines.…”

Section: Introductionmentioning

confidence: 99%

Vortex-induced vibrations of a cylinder in inelastic shear-thinning and shear-thickening fluids

2022

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Vortex-induced vibrations (VIV) of a cylinder in a Newtonian fluid is a model problem in fluid–structure interactions and has been studied extensively. In this work, we study the influence of shear-thinning and shear-thickening fluids on the VIV response of a one-degree-of-freedom flexibly-mounted cylinder. We consider a system with a mass ratio of $m^*=2$ and zero structural damping in shear-thinning and shear-thickening power-law fluids at $Re_0 = 15$ and $Re_0 = 200$ , respectively, defined based on the zero-shear-rate viscosity of the fluids. We investigate how the VIV amplitude and frequency, flow forces, and the vorticity contours change as the reduced velocity, $U^*$ , and fluid's time constant, $\lambda$ , change. When the results are compared based on $Re_0$ , shear-thinning fluids enhance the oscillations while shear-thickening fluids suppress them. If, however, we define a characteristic Reynolds number, $Re_{char}$ , based on a viscosity evaluated at the characteristic shear rate, $\dot {\gamma } = U/D$ , then at a constant $Re_{char}$ , the amplitude of response stays very similar for the shear-thinning, shear-thickening and Newtonian fluids. Despite this similarity, the observed far wake is different: shear thinning amplifies the generation of vorticity and reduces the extent of the wake, whereas shear thickening limits the generation of vorticity and extends the wake. Our findings show that the local apparent viscosity observed close to the cylinder placed in shear-thinning or shear-thickening fluids governs the VIV response of the cylinder.

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Effect of non‐ionic frothers on bubble characteristics in flotation: a review

Pan,

Gao,

Zhu

et al. 2024

J of Chemical Tech & Biotech

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The properties and synthesis of frothers have been the subject of scientific research for over a century owing to their extensive use in various industries. Given that the characteristics of bubbles are dependent on the nature of frother, such as in flotation slime, it is crucial to control the dosage of frother to achieve optimal effects. Excessive dosage leads to reagent waste whereas insufficient dosage results in resource waste, both hindering carbon emission reduction efforts. This paper provides a comprehensive review of existing literature regarding the impact of frothers on bubble behavior. The available literature demonstrates that the bubble size and velocity decrease as frother concentration increases. The underlying reasons for this phenomenon are discussed extensively. Furthermore, the relationship between bubble characteristics and hydrophile–lipophile balance (HLB) of frothers is examined. Finally, a correlation between bubble energy at critical coalescence concentration and HLB is established. These valuable insights for further investigation into frother properties. © 2024 Society of Chemical Industry (SCI).

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Flow-induced vibrations of a square prism free to oscillate in the cross-flow and inline directions

Abstract: Abstract

Cited by 18 publications

References 32 publications

Vortex-induced vibration of a two degree-of-freedom flexibly mounted circular cylinder in the crossflow direction

Vortex-induced vibration of a two degree-of-freedom flexibly mounted circular cylinder in the crossflow direction

Vortex-induced vibrations of a cylinder in inelastic shear-thinning and shear-thickening fluids

Effect of non‐ionic frothers on bubble characteristics in flotation: a review

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