An Investigation on Fully Developed Turbulent Flows in a Curved Channel

Eskinazi, S.; Yeh, Hsuan

doi:10.2514/8.3496

Cited by 109 publications

(17 citation statements)

References 6 publications

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“…Similar distribution of Reynolds shear stress has been observed in turbulent flows in curved channels as reported by Wattendorf (1935) and Eskinazi and Yeh (1956). The normalized Reynolds shear stress distributions in Fig.…”

Section: Reynolds Stressessupporting

confidence: 87%

Development of Two-Dimensional Wakes Within Curved Channels, Theoretical Framework and Experimental Investigation

Schobeiri

John

Pappu

1994

Volume 1: Turbomachinery

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The development of a wake flow downstream of a cylindrical rod within a curved channel under zero streamwise pressure gradient is theoretically and experimentally investigated. The measured asymmetric wake quantities such as the mean velocity and turbulent fluctuations in longitudinal and lateral directions as well as the turbulent shear stress are transformed from the probe coordinate system into the curvilinear wake eigen-coordinate system. For the transformed non-dimensionalized velocity defect and the turbulent quantities, affine profiles are observed throughout the flow regime. Based on these observations and using the transformed equations of motion and continuity, a theoretical frame work is established that generally describes the two-dimensional curvilinear wake flow. The theory also describes the straight wake as a special case, for which the curvature radius approaches infinity. The comparison of the theory with the experimental data pertaining to the curvilinear and straight wakes demonstrate the general validity of the theory.

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Section: Reynolds Stressessupporting

confidence: 87%

Development of Two-Dimensional Wakes Within Curved Channels, Theoretical Framework and Experimental Investigation

Schobeiri

John

Pappu

1994

Volume 1: Turbomachinery

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“…There is a close analogy between streamline curvature and buoyancy in laminar flows (Gortler 1959); however, the analogy is not quite so close in turbulent flows. This is evident from the early work of Prandtl (1929) and the experimental measurements of Wattendorf (1935), Schmidbauer (1936) and Eskinazi & Yeh (1956). Further evidence is also provided by the experiment of Johnson (1959), who found the correlation coefficient of temperature and velocity fluctuations to be approximately 0.7 in a shear flow over a heated flat plate.…”

Section: Examination Of the Curvaturelbuoyancy Analogymentioning

confidence: 84%

“…The importance of streamline curvature in a turbulent flow has been recognized by many investigators and various experimental efforts have been made to study its effects. For example, the effects of surface curvature on two-dimensional turbulent flows were investigated by Wattendorf (1935), Eskinazi & Yeh (1956), Giles, Nays & Sawyer (1966), Patel (1969), Ellis & Joubert (1974) and So & Mellor (1973, 1975. These studies show that curvature of the mean flow gives rise to a substantial change in the turbulent flow structure and an appreciable change in the measured mean velocity and wall shear stress.…”

Section: Introductionmentioning

confidence: 99%

A turbulence velocity scale for curved shear flows

1975

J. Fluid Mech.

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Assuming the turbulence length scale to be unaffected by streamline curvature, a turbulence velocity scale for curved shear flows is derived from the Reynolds-stress equations. Closure of the equations is obtained by using the scheme of Mellor & Herring (1973), and the Reynolds-stress equations are simplified by invoking the two-dimensional boundary-layer approximations and assuming that production of turbulent energy balances viscous dissipation. The resulting formula for the velocity scale has one free parameter, but this can be determined from data for non-rotating unstratified plane flows. Consequently there is no free constant in the derived expression. A single value of the constant is found to give good agreement between calculated and measured values of the velocity scale for a wide variety of curved shear flows.The result is also applied to test the validity and extent of the analogy between the effects of buoyancy and streamline curvature. This is done by comparing the present result with that obtained by Mellor (1973). Excellent agreement is obtained for the range −0·21 [les ]Rif[les ] 0·21. Therefore the present result provides direct evidence in support of the use of a Monin–Oboukhov (1954) formula for curved shear flows as proposed by Bradshaw (1969).

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“…Measurements of turbulent boundary layers along a convex surface obtained by So & Mellor (1973) indicated that Reynolds stress was decreased. Experimental work on the boundary layer over a concave surface is not as extensive, but the opposite effect was observed by Eskinazi & Yeh (1956) for a concave surface. The effects of stabilizing or destabilizing forces on the turbulent motion on a curved surface was first discussed by Prandtl (1930).…”

Section: Introductionmentioning

confidence: 99%

Turbulent flow over a flexible wall undergoing a streamwise travelling wave motion

et al. 2003

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Direct numerical simulation is used to study the turbulent flow over a smooth wavy wall undergoing transverse motion in the form of a streamwise travelling wave. The Reynolds number based on the mean velocity U of the external flow and wall motion wavelength λ is 10 170; the wave steepness is 2πa/λ = 0.25 where a is the travelling wave amplitude. A key parameter for this problem is the ratio of the wall motion phase speed c to U , and results are obtained for c/U in the range of −1.0 to 2.0 at 0.2 intervals. For negative c/U , we find that flow separation is enhanced and a large drag force is produced. For positive c/U , the results show that as c/U increases from zero, the separation bubble moves further upstream and away from the wall, and is reduced in strength. Above a threshold value of c/U ≈ 1, separation is eliminated; and, relative to smallc/U cases, turbulence intensity and turbulent shear stress are reduced significantly. The drag force decreases monotonically as c/U increases while the power required for the transverse motion generally increases for large c/U ; the net power input is found to reach a minimum at c/U ≈ 1.2 (for fixed U). The results obtained in this study provide physical insight into the study of fish-like swimming mechanisms in terms of drag reduction and optimal propulsive efficiency.

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An Investigation on Fully Developed Turbulent Flows in a Curved Channel

Cited by 109 publications

References 6 publications

Development of Two-Dimensional Wakes Within Curved Channels, Theoretical Framework and Experimental Investigation

Development of Two-Dimensional Wakes Within Curved Channels, Theoretical Framework and Experimental Investigation

A turbulence velocity scale for curved shear flows

Turbulent flow over a flexible wall undergoing a streamwise travelling wave motion

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