Time resolved measurements of vortex-induced vibrations of a positively buoyant tethered sphere in uniform water flow

Eshbal, L.; Krakovich, A.; Hout, R. van

doi:10.1016/j.jfluidstructs.2012.07.003

Cited by 15 publications

(9 citation statements)

References 31 publications

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“…They detected two different bifurcation regions: the first one in which the sphere did not oscillate, coinciding with the onset of an asymmetric shedding of hairpin vortices observed for a stationary sphere, and the second (lock-in) region, which started at U* & 2.2. In 2013, the same authors [3] analyzed both light (m* = 0.392) and heavy (m* = 7.87) tethered spheres for 2.2 B U* B 13.5 which, after an initially stationary state, started to oscillate at U* [ 2.2 (Re = 430) for m* = 0.392, as showed in the previous study [15], and at U* [ 3.5 (Re = 673) for m* = 7.87.…”

Section: Introductionmentioning

confidence: 68%

“…Then, the kth elements of the phase average and phase standard deviation are calculated as [Eqs. (15) and (16), respectively]:…”

Section: Experimental Apparatus and Measurement Techniquesmentioning

confidence: 99%

“…Parallel experiments on light tethered spheres (m* = 0.392) in uniform flow at reduced velocities, 2.2 B U* B 10.1, corresponding to 430 B Re B 1925, were carried out by Eshbal et al [15]. They detected two different bifurcation regions: the first one in which the sphere did not oscillate, coinciding with the onset of an asymmetric shedding of hairpin vortices observed for a stationary sphere, and the second (lock-in) region, which started at U* & 2.2.…”

Section: Introductionmentioning

confidence: 99%

“…Nonetheless, phase average is a common technique in analyzing periodic signals, and it has been used in many VIV works to represent the velocity and vorticity fields of the wake. For example, some studies such as Krakovich et al [3], Govardhan and Williamson [10] and Eshbal et al [15] applied this technique to experimentally investigate the wake of tethered spheres undergoing VIVs.…”

Section: Introductionmentioning

confidence: 99%

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An analysis method of the vortex-induced vibrations of a tethered sphere

2020

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Vortex-induced vibrations (VIV) in systems with more than one degree of freedom often present complex synchronization among the motion components, also hidden by the randomness that characterizes the motion itself. A phase average method has been here developed and applied to the displacements of a tethered sphere, at low mass and damping, to analyze its xy trajectories over a wide range of reduced velocities, 5 ≤ U* ≤ 25 (Reynolds numbers, 5.1 × 103 ≤ Re ≤ 2.67 × 104). This method has allowed the identification of both the periodic and chaotic contribution of each motion component, accurately reconstructing the underlying trajectory periodic pattern. The two classical vibration modes, I and II, have been also observed. The method developed here was able to better rebuild the experimental data compared to other methods found in the relevant literature, providing useful insights into the study of the dynamic response of a freely-oscillating tethered sphere immersed in a steady flow.

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Section: Introductionmentioning

confidence: 68%

“…Then, the kth elements of the phase average and phase standard deviation are calculated as [Eqs. (15) and (16), respectively]:…”

Section: Experimental Apparatus and Measurement Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An analysis method of the vortex-induced vibrations of a tethered sphere

2020

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“…Using the effective added mass, Govardhan & Williamson (2005) estimated that m * crit is approximately 0.6 for a sphere. Eshbal, Krakovich & Hout (2012) investigated the VIV of a light tethered sphere with m * < m * crit , for the Reynolds-number range 430 Re 1925. As U * increased, they observed a continuously increasing trend in the r.m.s.…”

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confidence: 99%