Turbulent Flow Over a Plane Symmetric Sudden Expansion

Smyth, R.

doi:10.1115/1.3448974

Cited by 31 publications

(26 citation statements)

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“…The negative velocities inside the recirculation regions are overpredicted and there is a tendency for the calculated profiles to recover more rapidly in part due to the use of the law of the wall as confirmed by the recent DNS of Le et al [18] and the experiments of Jovic and Driver [25]. Further, the use of a two-layer model will not guarantee a better performance, since it has been reported that conflicting results have been obtained for backward-facing step flows by Chen and Patel [26] and Iacovides and Launder [27], who predicted the velocity profiles for a 1.125 expansion with a good accuracy, whereas for an expansion ratio of 1.5, Smyth [28] predicted a much stronger reverse flow than the experiments. Also, the results in the redevelopment region are sensitive to those obtained in the recirculation regions, where it is known that excessive diffusion in the shear layer is predicted by the present turbulence model.…”

Section: Calculationsmentioning

confidence: 99%

Flows through plane sudden-expansions

Zilwa

Khezzar

Whitelaw

2000

Int. J. Numer. Meth. Fluids

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Section: Calculationsmentioning

confidence: 99%

Flows through plane sudden-expansions

Zilwa

Khezzar

Whitelaw

2000

Int. J. Numer. Meth. Fluids

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“…Smyth 13 performed a comprehensive experimental study at Re= 20 140, but his measurements refer to an expansion ratio of 1.5 and a symmetric flow pattern. He found an approximately two-dimensional flow in the midplane of the channel, which seems reasonable in view of the high aspect ratio ͑A = 30.4͒ considered in his work.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional features of the turbulent flow through a planar sudden expansion

Casarsa

Giannattasio

2008

Physics of Fluids

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An experimental investigation of the turbulent flow downstream of a planar sudden expansion has been performed by means of a 2D particle image velocimetry ͑PIV͒ technique. Flow fields at the Reynolds number of 10 4 have been measured in several mutually perpendicular planes of a channel having an expansion ratio of 3 and an aspect ratio of 10. As usual for large expansion ratios, the separated flow exhibits a strong asymmetry about the expansion axis and, consequently, very different reattachment lengths on the two side walls of the channel. The mean flow turns out to be substantially symmetric about the midspan plane and strong three-dimensional effects are observed in wide portions of the separation bubbles adjacent to the upper and lower walls. The reattachment lengths exhibit significant spanwise variations that are particularly pronounced in the longer reattachment line. Measurements performed in a single flow plane at Re=4·10 4 show that the influence of the Reynolds number on the mean flow is not completely negligible in the considered variation range. Based on a careful analysis of the PIV data, a model of the three-dimensional mean flow structure in the separation bubbles has been conjectured and it is provided in the paper. The present investigation contributes to clarifying the controversial three-dimensional character of the turbulent flow in a planar sudden expansion and provides accurate and detailed reference data for numerical simulations.

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“…Furthermore, detailed quantitative information on this highly turbulent, reversing flow requires advanced velocity measurement techniques (such as laser Doppler anemometry), and the use of these techniques in sudden expansion flows has only begun in recent years. In recent years, laser Doppler anemometry (LDA) was used by Cherdron et al (1978) to study the axisymmetric sudden expansion, and by Smyth (1979) to investigate the plane, symmetric (double step) expansion. These studies provided information on the overall structure of the sudden expansion flow and helped identify various flow zones.…”

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confidence: 99%

Expansion ratio effects on the separated shear layer and reattachment downstream of a backward-facing step

Otugen¹

1991

Experiments in Fluids

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Experiments were carried out to study the behavior of the incompressible turbulent separated shear layer and subsequent reattachment, downstream of a backward-facing step in a channel. The main objective of the study was to determine the effect of the expansion ratio on the development of the mean velocity and turbulence intensity in the shear layer and on the evolution of wall static pressure downstream of the step. The step height-to-upstream channel height ratio was varied between 0.5 and 2.13 while all inlet conditions were kept constant. Both hot-wire anemometry and frequency shifted laser Doppler anemometry were used for the velocity measurements. The Reynolds number based on free stream velocity and channel height upstream of the step was 16,600. The expansion ratio was found to have a particularly strong influence in the development of the turbulent, separated shear layer. Larger step heightto-inlet channel height ratios lead to higher turbulence intensities and faster growth of the unstable shear layer. As a result of this, shorter normalized reattachment lengths occurred with lager expansion ratios. For all the expansion ratios studied, the mean reattachment lenght was uniform along the spanwise direction except very near the side walls. List of symbolsCp H h P Re

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Turbulent Flow Over a Plane Symmetric Sudden Expansion

Cited by 31 publications

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Flows through plane sudden-expansions

Flows through plane sudden-expansions

Three-dimensional features of the turbulent flow through a planar sudden expansion

Expansion ratio effects on the separated shear layer and reattachment downstream of a backward-facing step

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