Three-dimensional structures in a shallow flow

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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“…Qðx; y; z ¼ 0:5Þ (2004) and Cieślik et al (2010). In this study, Q is determined for the center x, y-plane (z = 0.5).…”

Section: Application Of Q Criterionmentioning

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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“…Apparently, shallow flows generated under the conditions of the experiments reported by Akkermans et al (2008aAkkermans et al ( , 2008bAkkermans et al ( , 2009) and Cieślik et al (2009bCieślik et al ( , 2009c do not behave in a quasi-2D fashion, as is commonly assumed in experimental shallow-flow studies related to 2D turbulence, see e.g. Tabeling et al (1991), Danilov et al (2002) and Shats et al (2005Shats et al ( , 2007.…”

Section: The Effect Of Vertical Confinement Of Shallow-layer Flowsmentioning

confidence: 77%

“…Under the assumption of two-dimensionality, the vortices induced by the magnets would interact and gradually give rise to larger coherent vortex structures, as illustrated for example by the numerical simulations by McWilliams (1984). Recent experiments by Cieślik et al (2009bCieślik et al ( , 2009c on shallow flows driven electromagnetically by a regular array of 10 × 10 magnets have revealed a different flow evolution; however, in the post-forcing stage the flow shows large-scale meandering structures rather than vortices. This is clearly observed in the streak photographs presented in figure 8: during the forcing ( figure 8(a)) the flow is organized in a regular array of 10 × 10 counter-rotating cells, but some time after the forcing has stopped large meandering currents are visible throughout the flow domain ( figure 8(b)).…”

Section: The Effect Of Vertical Confinement Of Shallow-layer Flowsmentioning

confidence: 99%

Studies on quasi-2D turbulence—the effect of boundaries

Heijst

Clercx

2009

Fluid Dyn. Res.

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This paper addresses the effects of domain boundaries on the behaviour of quasi-two-dimensional flows, thereby distinguishing between lateral boundaries of horizontal flow domains and the horizontal boundaries confining shallow fluid layers. As already discussed in some recent papers, the lateral walls may play an essential role in acting as sources of filamentary highamplitude vorticity, which usually affects the flow evolution in the interior of the domain. Besides, walls exert forces that may promote the self-organization of the flow, and hence contribute to a change in the net angular momentum of the flow. Both aspects will be reviewed briefly.In contrast to what is commonly assumed, shallow-layer flows may develop an essentially three-dimensional structure, with vertical gradients in the principal horizontal flow field and with significant vertical velocity components. These features have been found recently in experiments on electromagnetically generated flows in a shallow fluid layer. In this paper, we will discuss some of these experimental observations as well as some numerical simulation results that are helpful in explaining the observed flow dynamics.

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“…The strain-dominated regions can be identified by Q > 0, while rotation-dominated regions can be identified by Q < 0. The Okubo-Weiss function is valid for two-dimensional flow and has been successfully used by, among others, Vosbeek et al (1997), Isern-Fontanet et al (2004, Molenaar et al (2004), Cieślik et al (2010) andvan Hooff et al (2012). Figure 11b, d shows distributions of Q for cases…”

Section: Instantaneous Velocity Vorticity ω Z and Okubo-weiss Funcmentioning

confidence: 99%

PIV measurements of isothermal plane turbulent impinging jets at moderate Reynolds numbers

et al. 2017

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Three-dimensional structures in a shallow flow

Cited by 12 publications

References 18 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

Studies on quasi-2D turbulence—the effect of boundaries

PIV measurements of isothermal plane turbulent impinging jets at moderate Reynolds numbers

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