Momentum Transfer in Turbulent Separated Flow Past a Rectangular Cavity

Haugen, R. L.; Dhanak, A. M.

doi:10.1115/1.3625133

Cited by 58 publications

(17 citation statements)

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“…It is believed that the high rate of energy dissipation, associated with form drag generated by the steps, contributes to strong turbulent mixing throughout the entire flow. Although the quantitative values of turbulence intensity are large (Tu ~ 100%), they are similar to turbulence measurements in separated flows past rectangular cavity (Haugen and Dhanak 1966), in wakes between large stones (Sumer et al 2001), in developing shear region of plunging water jets (Chanson and Brattberg 1998) and in pipe flows (Mudde and Saito 2001). Note that only the metrology of Mudde and Saito was comparable to the present signal processing technique.…”

Section: Air-water Velocity and Velocity Fluctuation Profilessupporting

confidence: 74%

Air–water flows down stepped chutes: turbulence and flow structure observations

Chanson

Toombes

2002

International Journal of Multiphase Flow

207

179

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: Interactions between turbulent waters and atmosphere may lead to strong air-water mixing.This experimental study is focused on the flow down a staircase channel characterised by very strong flow aeration and turbulence. Interfacial aeration is characterised by strong air-water mixing extending down to the invert. The size of entrained bubbles and droplets extends over several orders of magnitude, and a significant number of bubble/droplet clusters was observed. Velocity and turbulence intensity measurements suggest high levels of turbulence across the entire air-water flow. The increase in turbulence levels, compared to single-phase flow situations, is proportional to the number of entrained particles.

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Section: Air-water Velocity and Velocity Fluctuation Profilessupporting

confidence: 74%

Air–water flows down stepped chutes: turbulence and flow structure observations

Chanson

Toombes

2002

International Journal of Multiphase Flow

207

179

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“…The mechanism is very similar to cases shown in Fig. 8 in which the vortices have been observed widely in field and laboratory (Liu 2006;Hangen and Dhanak 1966;van Schijndel 1998;Schmidt 1990). In the experiment by Liu (2006), the nonzero velocity w was artificially generated and then, the circulation shown in Fig.…”

Section: ½31supporting

confidence: 61%

Mechanism for initiating secondary currents in channel flows

Yang

2009

Can. J. Civ. Eng.

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This study investigates the underlying mechanisms that initiate secondary flow in developing turbulent flow along a corner. This is done by theoretical examination of the total shear stress, which is the time-averaged product of instantaneous streamwise velocity U and the velocity Vn normal to the interface. The study shows that lines of zero total shear stress exist in the flow region, which delineate the region of secondary flow. Therefore, the flow region is dividable and eight vortices occur in a duct flow. The theoretical and experimental results show that the division line, separating the neighboring secondary currents in a corner, is not always identical to the bisector of the corner, but deviates from the corner bisector if the aspect ratio is b/h = 1. By simplifying Reynolds equation in the near-bed region, we find that theoretically a lateral variation of streamwise velocity initiates the wall-tangent flow that drives the vortex in the region bounded by zero total shear stress. A simplified method for estimating the vortex center, near-bed secondary velocity, and shape of secondary currents has been proposed, and a good agreement between the measured and predicted features is achieved.Key words: dip-phenomenon, division line, Reynolds shear stress, secondary currents of Prandtl's second kind, turbulent energy, velocity distribution.Résumé : La présente étude examine les mécanismes sous-jacents qui initient un écoulement secondaire dans un écoule-ment turbulent en développement le long d'un coin. Cela est accompli en examinant de manière théorique la contrainte totale en cisaillement, laquelle est le produit pondéré dans le temps de la composante longitudinale instantanée de la vitesse U et la vitesse Vn perpendiculaire à l'interface. L'étude montre que, dans la région de l'écoulement, il existe des lignes de zéro contrainte totale de cisaillement qui délimitent la région d'écoulement secondaire. C'est pourquoi la région d'écou-lement peut être divisée et que huit vortex surviennent dans un écoulement en canalisation. Les résultats théoriques et expérimentaux montrent que la ligne de division, séparant les courants secondaires avoisinants dans un coin, n'est pas toujours identique à la bissectrice du coin, mais qu'elle dévie de la bissectrice du coin si le rapport de forme b/h = 1. En simplifiant l'équation de Reynolds dans la région près du lit, les résultats théoriques montrent qu'une variation latérale de la composante longitudinale de la vitesse initie l'écoulement tangent au mur qui génère le vortex dans la région limitée par la contrainte totale de cisaillement zéro. Une méthode simplifiée pour estimer le centre du vortex, la vitesse secondaire près du lit et la forme des courants secondaires a été proposée et une bonne corrélation a été obtenue entre les paramètres mesurés et prédits.

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“…This flow behavior affects the incident boundary layer, i.e. skin friction coefficient, mean velocity profiles and turbulence intensity distribution [4][5][6][7][8][9]. Elavarasan et al [4] found an increase in u , the rootmean-square value of the streamwise velocity, just downstream of the cavity.…”

Section: Introductionmentioning

confidence: 96%

Non-oscillating/Oscillating Shear Layer over a Large Deep Cavity at Low-Subsonic Speeds

Hassan

Keirsbulck

Labraga

2008

Flow Turbulence Combust

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The flow over a deep cavity at low subsonic velocity is considered in the present paper. The cavity length-to-depth aspect ratio is L/H = 0.2. Single hot-wire measurements characterized the incident turbulent boundary layer and show the influence of the cavity on the streamwise statistic components just downstream from the cavity. The streamwise mean and fluctuating velocity profiles are affected by the cavity. PIV measurements reveal the presence for ejection-like events responsible of local perturbations of the skewness and the flatness coefficients. Time-resolved PIV technic is also used to characterize phase properties of shear layer oscillating cycle. It is shown that for deep cavity with first Rossiter mode, only one vortical structure is formed at the cavity leading edge. Then, it grows while convecting downstream along the shear layer. A well-defined ejection process begins after the vortex impact near the cavity downstream corner. A cylinder device placed spanwisely near the cavity leading edge eliminates the resonance and highly modifies the behavior of the shear layer flow. In fact, the shear layer could be divided into upper and lower parts with different structure aspects.

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Momentum Transfer in Turbulent Separated Flow Past a Rectangular Cavity

Cited by 58 publications

References 0 publications

Air–water flows down stepped chutes: turbulence and flow structure observations

Air–water flows down stepped chutes: turbulence and flow structure observations

Mechanism for initiating secondary currents in channel flows

Non-oscillating/Oscillating Shear Layer over a Large Deep Cavity at Low-Subsonic Speeds

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