Vortex shedding and heat transfer in rotationally oscillating cylinders

Sellappan, Prabu; Pottebaum, Tait

doi:10.1017/jfm.2014.191

Cited by 23 publications

(8 citation statements)

References 46 publications

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“…Their findings also revealed that the heat transfer rate reduced at high oscillating amplitudes (

α = 4

) for all oscillating frequencies. More details on this problem can be found in 20–23 . It is also important to keep in mind that the forced oscillation does not affect the heat convection outside the lock‐on regime 16,24 …”

Section: Introductionmentioning

confidence: 99%

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Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

2021

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“…Their findings also revealed that the heat transfer rate reduced at high oscillating amplitudes (

α = 4

Section: Introductionmentioning

confidence: 99%

“…More details on this problem can be found in. [20][21][22][23] It is also important to keep in mind that the forced oscillation does not affect the heat convection outside the lock-on regime. 16,24 Over the years, constant cylinder temperature has been the only subject of study in flow past cylinders.…”

mentioning

confidence: 99%

Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

2021

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“…Periodic external forcing in active lock-on is usually realized through two types of activeflow-control technologies, i.e., the cylinder's prescribed oscillations and fluidic perturbations. The former includes the cylinder's rotational oscillation [11,[13][14][15][16][17] as well as translational oscillation in the transverse direction [1,[18][19][20][21] and in the streamwise direction [20,[22][23][24][25], whereas the latter includes fluidic perturbations imposed in the transverse direction [26] and in the streamwise direction [2,4,[27][28][29]. Primary lock-on was observed when the cylinder underwent transverse or rotational oscillation, or when transverse fluidic perturbation was introduced, both at a frequency close to the natural vortex shedding frequency.…”

Section: Introductionmentioning

confidence: 99%

Lock-on of vortex shedding to a pair of synthetic jets with phase difference

Wang

Tang

et al. 2017

Phys. Rev. Fluids

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This paper furthers our understanding of lock-on that is induced by periodic external forcing. The effect of forcing phase difference is investigated. An extended linear theory is proposed to predict the centers of various lock-on regimes, including harmonic, subharmonic, and superharmonic lock-on, in a parametric map spanned by the forcing frequency and phase difference. It reveals that when the forcing frequency is equal to the natural vortex shedding frequency or its integer multiple, harmonic or subharmonic lock-on occurs at particular forcing phase differences, whereas when the forcing frequency is a submultiple of the natural shedding frequency, superharmonic lock-on occurs. To confirm this theory and also further determine the shape and size of each lock-on regime, a series of numerical simulations is conducted on a circular-cylinder flow system with periodic external forcing being realized by a pair of synthetic jets (SJs). At a Reynolds number 100 and under moderate SJ forcing, five lock-on regimes are captured, including the primary, secondary, tertiary, and first-and second-superharmonic lock-on. It is found that these lock-on regimes are generally in a rhomboidal shape, and their size gradually reduces when the SJ frequency is away from the natural vortex shedding frequency. With these simulations, the aerodynamic forces and wake formation in each lock-on regime are analyzed and compared, with the discussion being focused on the effects of SJ frequency and phase difference. Furthermore, stability analysis is conducted to reveal more flow physics related to lock-on.

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“…These studies provided insights on how the lock-on parameter space was affected by changing the amplitude and forcing frequency of the cylinder. Effect of heat transfer to the lock-on boundaries and the new modes were further described by Sellappan & Pottebaum (2014a) and Mittal & Al-Mdallal (2018). Recently, experimental studies on a rotationally oscillating cylinder with an attached flexible filament was conducted by Sunil, Kumar & Poddar (2022).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of three-dimensional modes in the wake of a rotationally oscillating cylinder

et al. 2022

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Three-dimensionalities in the wake of flow past a circular cylinder executing sinusoidal rotary oscillations about its axis is studied experimentally. The results of water tunnel experiments on a rotationally oscillating cylinder for Reynolds number of 250 with varying amplitude and forcing frequency are discussed. Qualitative studies using hydrogen bubble and laser-induced fluorescence flow visualisation techniques are performed. Observation made for oscillating amplitude, $\theta _{0} = {\rm \pi}/4$ and $\theta _{0}=3{\rm \pi} /4$ , and a low normalised forcing frequency, $FR$ , of 0.75 and 0.5, respectively, confirmed a mode having a spanwise non-dimensional wavelength of $\sim$ 1.8 which is also observed for a rotating cylinder. On increasing forcing frequency this mode disappears and a new mode with a bean-shaped structure and a much smaller spanwise normalised wavelength of $\sim$ 0.8 appears at an $FR$ of 1 and an oscillation amplitude of ${\rm \pi} /2$ . This mode remains almost stable until a forcing frequency of $FR=1.4$ . At higher forcing frequency, $FR=2.75$ , and oscillation amplitude of $3{\rm \pi} /4$ , a mode with cellular structure and a normalised spanwise wavelength of $\sim$ 1.6 is identified. The cells in this mode flatten up with increasing downstream distance and are shed alternately with respect to the adjacent cell. Certain combinations of forcing parameters resulted in a forced two-dimensionality of the wake. Quantitative studies using hot-wire measurements and particle image velocimetry confirm the presence of these modes and wake characteristics. Wake mode map in the forcing frequency and amplitude plane is presented showing regions of newly discovered modes and wake lock-on boundaries.

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Vortex shedding and heat transfer in rotationally oscillating cylinders

Cited by 23 publications

References 46 publications

Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

Heat transfer past rotationally oscillating circular cylinder heated with time‐periodic pulsating temperature in a uniform flow

Lock-on of vortex shedding to a pair of synthetic jets with phase difference

Experimental investigation of three-dimensional modes in the wake of a rotationally oscillating cylinder

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