A numerical study of oscillating flow around a circular cylinder

Justesen, Peter

doi:10.1017/s0022112091001040

Cited by 145 publications

(86 citation statements)

References 19 publications

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“…Also, the length of the separated zone is relatively independent of KC. This is in contrast to higher Reynolds number (Re > 100) studies [6][7][8] where vortex formation and shedding are primarily dependent on KC.…”

contrasting

confidence: 65%

“…Few studies [6][7][8] have been reported in the literature on the pulsatile flow past the stationary cylinder for Reynolds number (Re) >100 focusing on marine applications. As TAL operating Reynolds number is between 5 and 10, flow dynamics is expected to be different and no correlation can be made from studies available in the literature.…”

mentioning

confidence: 99%

“…As TAL operating Reynolds number is between 5 and 10, flow dynamics is expected to be different and no correlation can be made from studies available in the literature. [6][7][8] An apparent closely related class of a fluid mechanics problem 9 which involving cylinder oscillation in a quiescent or a low Reynolds number, also cannot be correlated with pulsatile flow over the fix cylinder case. As they are fundamentally different and Galilean transformation between them is not possible.…”

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confidence: 99%

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Pulsatility role in cylinder flow dynamics at low Reynolds number

2012

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We present dynamics of pulsatile flow past a stationary cylinder characterized by three non-dimensional parameters: the Reynolds number (Re), non-dimensional amplitude (A) of the pulsatile flow velocity, and Keulegan-Carpenter number (KC = Uo/Dωc). This work is motivated by the development of total artificial lungs (TAL) device, which is envisioned to provide ambulatory support to patients. Results are presented for 0.2 ≤ A ≤ 0.6 and 0.57 ≤ KC ≤ 2 at Re = 5 and 10, which correspond to the operating range of TAL. Two distinct fluid regimes are identified. In both regimes, the size of the separated zone is much greater than the uniform flow case, the onset of separation is function of KC, and the separation vortex collapses rapidly during the last fraction of the pulsatile cycle. The vortex size is independent of KC, but with an exponential dependency on A. In regime I, the separation point remains attached to the cylinder surface. In regime II, the separation point migrates upstream of the cylinder. Two distinct vortex collapse mechanisms are observed. For A < 0.4 and all KC and Re values, collapse occurs on the cylinder surface, whereas for A > 0.4 the separation vortex detaches from the cylinder surface and collapses at a certain distance downstream of the cylinder. The average drag coefficient is found to be independent of A and KC, and depends only on Re. However, for A > 0.4, for a fraction of the pulsatile cycle, the instantaneous drag coefficient is negative indicating a thrust production.

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confidence: 65%

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confidence: 99%

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Pulsatility role in cylinder flow dynamics at low Reynolds number

2012

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“…The boundary layer has been theoretically predicted and often experimentally confirmed on large structures for both longitudinal and transverse oscillatory flows (Raney et al, 1954;Bertelsen et al, 1973;Williamson, 1985;Obasaju et al, 1988;Justesen, 1991;Tatsuno and Bearman, 1990). These studies were, however, conducted for Reynolds and Strouhal numbers very different from those of biological relevance, with the exception of the studies by Holtsmark et al (Holtsmark et al, 1954) and Wang (Wang, 1968).…”

Section: Introductionmentioning

confidence: 99%

Air-flow sensitive hairs: boundary layers in oscillatory flows around arthropod appendages

Steinmann

Casas

Krijnen

et al. 2006

Journal of Experimental Biology

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SUMMARY The aim of this work is to characterize the boundary layer over small appendages in insects in longitudinal and transverse oscillatory flows. The problem of immediate interest is the early warning system in crickets perceiving flying predators using air-flow-sensitive hairs on cerci, two long appendages at their rear. We studied both types of oscillatory flows around small cylinders using stroboscopic micro-particle image velocimetry as a function of flow velocity and frequency. Theoretical predictions are well fulfilled for both longitudinal and transverse flows. Transverse flow leads to higher velocities than longitudinal flow in the boundary layer over a large range of angles between flow and cylinder. The strong spatial heterogeneity of flow velocities around filiform-shaped appendages is a rich source of information for different flow-sensing animals. Our results suggest that crickets could perceive the direction of incoming danger by having air-flow-sensitive hairs positioned around their entire cerci. Implications for biomimetic flow-sensing MEMS are also presented.

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“…Wang and Dalton 10 obtained a ®nite difference solution of the Navier±Stokes equations for KC 1±12 and Re 100±3000. Justesen 11 conducted a detailed computational study of planar oscillatory¯ow, also employing the ®nite difference technique, for b ranging between 196 and 1035 and KC extending up to 26. He observed various vortex-shedding regimes when KC exceeded approximately 7, while his computed drag values were very similar to those predicted by Wang 7 for KC extending up to 1Á5 for b 1035 and up to 2 for lower values of b.…”

Section: Introductionmentioning

confidence: 99%

Viscous oscillatory flow around a circular cylinder at low Keulegan-Carpenter numbers and frequency parameters

Iliadis

Anagnostopoulos

1998

Int. J. Numer. Meth. Fluids

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The results of a numerical study of the viscous oscillating flow around a circular cylinder at low Keulegan–Carpenter numbers (KC) and frequency parameters (β) are presented in this paper. The finite element method was used for the solution of the Navier–Stokes equations in the formulation where the streamfunction and vorticity are the field variables. The computation was conducted at Keulegan–Carpenter numbers extending up to KC=15 and frequency parameters ranging between β=6 and 100. At low values of the Keulegan–Carpenter number the flow remains symmetrical. As the Keulegan–Carpenter number is increased over a certain value which depends also on the frequency parameter, asymmetries appear in the flow which are eventually amplified and lead finally to complex vortex‐shedding patterns, some of which are markedly different from those observed at higher frequency parameters. The solution revealed that although for certain values of KC and β the shedding of vortices is periodic, there also exists a complicated flow regime in which the flow is not periodic but switches between different modes in consecutive cycles of flow oscillation. For the various flow cases examined, the traces of the hydrodynamic forces are presented and the hydrodynamic coefficients and RMS values of the in‐line force are compared with experimental evidence. © 1998 John Wiley & Sons, Ltd.

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A numerical study of oscillating flow around a circular cylinder

Cited by 145 publications

References 19 publications

Pulsatility role in cylinder flow dynamics at low Reynolds number

Pulsatility role in cylinder flow dynamics at low Reynolds number

Air-flow sensitive hairs: boundary layers in oscillatory flows around arthropod appendages

Viscous oscillatory flow around a circular cylinder at low Keulegan-Carpenter numbers and frequency parameters

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