The turbulent wall jet

Launder, B. E.; Rodi, W.

doi:10.1016/0376-0421(79)90002-2

Cited by 235 publications

(100 citation statements)

References 28 publications

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“…The inner region, or inner layer, runs from the wall to the point of maximum velocity U M and is similar to a wall boundary layer, whereas the outer region, or outer layer, consists of the remainder of the wall jet and can be seen as a free shear layer. A formal description of the wall jet is given by Launder and Rodi (1981): ''A wall jet may be defined as a shear flow directed along a wall where, by virtue of the initially supplied momentum, at any station, the streamwise velocity over some region within the shear flow exceeds that in the external stream.'' Wall jets can be subdivided in two-dimensional (plane) and three-dimensional wall jets.…”

Section: Introductionmentioning

confidence: 99%

“…Later, turbulent wall jets were experimentally investigated by Bakke (1957), Sigalla (1958), Bradshaw and Gee (1960) and Schwarz and Cosart (1961). An extensive overview of experimental work until 1980 is given by Launder and Rodi (1981). Wygnanski et al (1992), Sheu (1994, 1996), Gogineni and Shih (1997), Amitay and Cohen (1997), Eriksson et al (1998) are just a few examples of studies in which the wall jet was experimentally analyzed during the last decades of the twentieth century.…”

Section: Introductionmentioning

confidence: 99%

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PIV measurements of a plane wall jet in a confined space at transitional slot Reynolds numbers

et al. 2012

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Wall jets are important for a wide variety of engineering applications, including ventilation of confined spaces and cooling and drying processes. Although a lot of experimental studies have been devoted to wall jets, many of these have focused on laminar or turbulent wall jets. There is a lack of experimental data on transitional wall jets, especially transitional wall jets released into a confined space or enclosure. This paper presents flow visualizations and high-resolution Particle Image Velocimetry measurements of isothermal transitional plane wall jets injected through a rectangular slot in a confined space. As opposed to many previous studies, not only the wall jet region but also the recirculation region in the remainder of the enclosure is analyzed. The data and analysis in this paper provide new insights into the behavior of transitional plane wall jets in a confined space and will be useful for the validation of numerical simulations of this type of jets.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

PIV measurements of a plane wall jet in a confined space at transitional slot Reynolds numbers

et al. 2012

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“…This implies that the energy-containing eddies are not in equilibrium with the mean flow near the location of the velocity maximum. Launder & Rodi (1981) presented a detailed review of the topic. Wygnasnski et al (1992) investigated the similarity of the far field of a wall jet and George et al (2000) developed a general similarity theory.…”

Section: Introductionmentioning

confidence: 99%

Near-field flow structure of a confined wall jet on flat and concave rough walls

Albayrak¹,

Hopfinger²,

Lemmin³

2008

J. Fluid Mech.

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Experimental results are presented of the mean flow and turbulence characteristics in the near field of a plane wall jet issuing from a nozzle onto flat and concave walls consisting of fixed sand beds. This is a flow configuration of interest for sediment erosion, also referred to as scouring. The measurements were made with an acoustic profiler that gives access to the three components of the instantaneous velocities. For the flat-wall flow, it is shown that the outer-layer spatial growth rate and the maxima of the Reynolds stresses approach the values accepted for the far field of a wall jet at a downstream distance x/b 0 ≈ 8. These maxima are only about half the values of a plane free jet. This reduction in Reynolds stresses is also observed in the shear-layer region, x/b 0 < 6, where the Reynolds shear stress is about half the value of a free shear layer. At distances x/b 0 > 11, the maximum Reynolds shear stress approaches the value of a plane free jet. This change in Reynolds stresses is related to the mean vertical velocity that is negative for x/b 0 < 8 and positive further downstream. The evolution of the inner region of the wall jet is found to be in good agreement with a previous model that explicitly includes the roughness length.On the concave wall, the mean flow and the Reynolds stresses are drastically changed by the adverse pressure gradient and especially by the development of Görtler vortices. On the downslope side of the scour hole, the flow is nearly separating with the wall shear stress tending to zero, whereas on the upslope side, the wall-friction coefficient is increased by a factor of about two by Görtler vortices. These vortices extend well into the outer layer and, just above the wall, cause a substantial increase in Reynolds shear stress.

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“…According to the wall jet theory the maximum velocity of the profile um and the outlet velocity u0 have the following relationship [23] …”

Section: Calculation Of Region Cmentioning

confidence: 99%

The Effects of Fluid Viscosity on the Orifice Rotameter

Jiang

Zhang

et al. 2016

Measurement Science Review

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Due to the viscous shear stress, there is an obvious error between the real flow rate and the rotameter indication for measuring viscous fluid medium. At 50 cSt the maximum error of DN40 orifice rotameter is up to 35 %. The fluid viscosity effects on the orifice rotameter are investigated using experimental and theoretical models. Wall jet and concentric annulus laminar theories were adapted to study the influence of viscosity. And a new formula is obtained for calculating the flow rate of viscous fluid. The experimental data were analyzed and compared with the calculated results. At high viscosity the maximum theoretical results error is 6.3 %, indicating that the proposed measurement model has very good applicability.

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The turbulent wall jet

Cited by 235 publications

References 28 publications

PIV measurements of a plane wall jet in a confined space at transitional slot Reynolds numbers

PIV measurements of a plane wall jet in a confined space at transitional slot Reynolds numbers

Near-field flow structure of a confined wall jet on flat and concave rough walls

The Effects of Fluid Viscosity on the Orifice Rotameter

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