Experimental investigation of a confined flow downstream of a circular cylinder centred between two parallel walls

Rehimi, Ferid; Aloui, Fethi; Nasrallah, Sassi Ben; Doubliez, Louis; Legrand, Jack

doi:10.1016/j.jfluidstructs.2007.12.011

Cited by 86 publications

(46 citation statements)

References 29 publications

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“…Also, it is worth noting that in the case of 510mm, the modes appear to be in pairs of similar energy contents (1-2, 3-4, 5-6 and so forth). This observation, which has been reported before [23][24][25] , constitutes a characteristic of single-frequency oscillations and has been attributed to vortex advection.…”

Section: B Pod Analysissupporting

confidence: 74%

Proper Orthogonal Decomposition Analysis of a Turbulent Swirling Self-Excited Premixed Flame

Kypraiou

Dowling

Mastorakos

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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Section: B Pod Analysissupporting

confidence: 74%

Proper Orthogonal Decomposition Analysis of a Turbulent Swirling Self-Excited Premixed Flame

Kypraiou

Dowling

Mastorakos

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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“…A similar increase of Re c due to confinement has also been reported for a lower ratio D/H = 1/3. 21 Also, the Strouhal number St often increases with Re above the threshold for vortex shedding 12,20 while it decreases instead with Re for the type of instabilities studied here (dotted line in the inset of Fig. 8).…”

Section: Discussionmentioning

confidence: 68%

Oscillations and translation of a free cylinder in a viscous confined flow

2013

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An oscillatory instability has been observed experimentally on an horizontal cylinder free to move and rotate between two parallel vertical walls of distance H. The vertical motion of the cylinder, its rotation about its axis, and its transverse motion across the gap have been investigated as a function of its diameter D, its density ρs, of the mean vertical velocity U of the fluid, and of its viscosity ν. The relevant Reynolds number Re is shown to be based on the cell aperture H and on the relative velocity Vr between the fluid and the cylinder. For a blockage ratio D/H above 0.5 and Re above 20, oscillations of the rolling angle of the cylinder about its axis and of its transverse coordinate in the gap were observed together with periodic variations of the vertical velocity. For a given fluid-cylinder pair, the relative velocity Vr as well as the frequency f and the amplitude of the transverse velocity for these oscillations are nearly independent of the flow velocity U. For given cylinder density and fluid characteristics, f is also nearly independent of the ratio D/H in the range investigated. The oscillations could be observed down to values of Re as low as 30: this is lower than usual values for vortex shedding in confined geometries, which suggests that one might deal with a different instability mechanism.

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“…While Re c increases with confinement up to h > 1, confinement is destabilizing in the range 0.43 < h < 1, before recovering a stabilizing influence for 0.19 < h < 0.43 and revealing, at these strong confinements, more complex dynamics than supercritical Hopf bifurcation. The stabilizing effect shown by Sahin & Owens (2004) for h > 1 was confirmed by the recent experimental study of Rehimi et al (2008), conducted on confined wakes (h = 2) past a circular cylinder, who found Re c = 108, compared to the classical Re c = 47 for unconfined cylinder wakes (see Williamson 1996 for a comprehensive review).…”

mentioning

confidence: 71%

Influence of confinement on a two-dimensional wake

Biancofiore¹,

Gallaire

Pasquetti³

2011

J. Fluid Mech.

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The spatio-temporal development of an incompressible two-dimensional viscous wake flow confined by two flat slipping plates is investigated by means of direct numerical simulation (DNS), using a spectral Chebyshev multi-domain method. The limit between unstable and stable configurations is determined with respect to several non-dimensional parameters: the confinement, the velocity ratio and two different Reynolds numbers, 100 and 500. The comparison of such limit curves with theoretical results obtained by Juniper (J. Fluid Mech., vol. 565, 2006, pp. 171-195) confirms the existence of a region at moderate confinement where the instability is maximal. Moreover, instabilities are also observed under sustained co-flow, in the form of a vacillating front. Using a direct computation of the two-dimensional base flow, we perform a local linear stability analysis for several velocity profiles prevailing at different spatial locations, so as to determine the local spatio-temporal nature of the flow: convectively unstable or absolutely unstable. Comparisons of the DNS and local stability analysis results are provided and discussed.

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Experimental investigation of a confined flow downstream of a circular cylinder centred between two parallel walls

Cited by 86 publications

References 29 publications

Proper Orthogonal Decomposition Analysis of a Turbulent Swirling Self-Excited Premixed Flame

Proper Orthogonal Decomposition Analysis of a Turbulent Swirling Self-Excited Premixed Flame

Oscillations and translation of a free cylinder in a viscous confined flow

Influence of confinement on a two-dimensional wake

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