Unsteady phenomena of an oscillating turbulent jet flow inside a cavity: Effect of aspect ratio

Mataoui, Amina; Schiestel, Roland

doi:10.1016/j.jfluidstructs.2008.03.010

Cited by 29 publications

(18 citation statements)

References 37 publications

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“…However, for sufficiently wide cavities, these oscillations are not present. 7,8 From Figure 10, it follows that the system is stable for δ < 1. As δ = rτ, an approximate relation between the critical Reynolds number and the width to nozzle diameter ratio can be found, …”

Section: Model Applicationmentioning

confidence: 98%

“…For very wide cavities, the domain becomes unbounded in one direction, and the self-sustained oscillation disappears. 7 A jet in such a wide cavity shows meandering, self-similar behavior. 8 For decreasing cavity width, the oscillation frequency increases, 7,9 until the cavity geometry approaches that of a sudden expansion, where strong asymmetries and oscillations are present as well.…”

Section: Introductionmentioning

confidence: 98%

“…7 A jet in such a wide cavity shows meandering, self-similar behavior. 8 For decreasing cavity width, the oscillation frequency increases, 7,9 until the cavity geometry approaches that of a sudden expansion, where strong asymmetries and oscillations are present as well. [10][11][12] A vast amount of fluidic oscillators exists, 3,6,13,14 which are, for example, found in backward facing steps, flows over cavities, 15 and jets through orifices.…”

Section: Introductionmentioning

confidence: 98%

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Dynamics of an oscillating turbulent jet in a confined cavity

et al. 2015

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We demonstrate how the self-sustained oscillation of a confined jet in a thin cavity can be quantitatively described by a zero-dimensional model of the delay differential equation type with two a priori predicted model constants. This model describes the three phases in self-sustained oscillations: (i) pressure driven growth of the oscillation, (ii) amplitude limitation by geometry, and (iii) delayed destruction of the recirculation zone. The two parameters of the model are the growth rate of the jet angle by a pressure imbalance and the delay time for the destruction of this pressure imbalance. We present closed relations for both model constants as a function of the jet Reynolds number Re, the inlet velocity vin, the cavity width W, and the cavity width over inlet diameter W/d and we demonstrate that these model constants do not depend on other geometric ratios. The model and the obtained model constants have been successfully validated against three dimensional large eddy simulations, and planar particle image velocimetry measurements, for 1600 < Re ≤ 7100 and 20 ≤ W/d < 50. The presented model inherently contains the transition to a non-oscillating mode for decreasing Reynolds numbers or increasing W/d-ratios and allows for the quantitative prediction of the corresponding critical Reynolds number and critical W/d.

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Section: Model Applicationmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

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Dynamics of an oscillating turbulent jet in a confined cavity

et al. 2015

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“…1,2 Flows in which self-sustained oscillations occur are (amongst others): jets issuing into a thin cavity, [3][4][5][6][7][8][9] the flow over backward facing steps, 10,11 and flows over cavities. [12][13][14][15] The self-sustained oscillations have a much lower frequency than those produced by shear layer instabilities.…”

Section: Introductionmentioning

confidence: 99%

Effects of electromagnetic forcing on self-sustained jet oscillations

et al. 2014

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The influence of electromagnetic forcing on self-sustained oscillations of a jet issuing from a submerged nozzle into a thin vertical cavity (width W much larger than thickness T) has been studied using particle image velocimetry. A permanent Lorentz force is produced by applying an electrical current across the width of the cavity in conjunction with a magnetic field from three permanent magnets across its thickness. As a working fluid a saline solution is used. The magnetic field is in the north-south-north configuration, such that the Lorentz force can be applied in an up-down-up configuration or in a down-up-down configuration by switching the direction of the electrical current. A critical Stuart number Nc was found. For N < Nc, the jet oscillates with a constant Strouhal number St, independent of the Reynolds number Re. For N > Nc and an oscillation enhancing up-down-up configuration of the Lorentz force, St grows with N as St \documentclass[12pt]{minimal}\begin{document}$\propto \sqrt{\mathrm{N}}$\end{document}∝N. In contrast, for N > Nc and an oscillation suppressing down-up-down configuration of the Lorentz force, all jet oscillations are suppressed.

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“…1). Many researchers [8][9][10][11][12][13] have shown that, when the jet is set in the midplane of a cavity, an oscillatory flow occurs. These self-sustained oscillations are due to the instability produced by the configuration of a plane jet located between two symmetrical lateral vortices.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigations on Heat Transfer of Self-Sustained Oscillation of a Turbulent Jet Flow Inside a Cavity

Iachachene

Mataoui

Halouane

2015

Journal of Heat Transfer

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Computations of heat transfer and fluid flow of a plane isothermal fully developed turbulent plane jet flowing into a rectangular hot cavity are reported in this paper. Both velocity and temperature distributions are computed by solving the two-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) equations. This approach is based on onepoint statistical modeling using the energy-specific dissipation (k-x) turbulence model. The numerical predictions are achieved by finite volume method. This problem is relevant to a wide range of practical applications including forced convection and the ventilation of mines, enclosure, or corridors. The structural properties of the flow and heat transfer are described for several conditions. An oscillatory regime is evidenced for particular jet location, inducing for each variable a periodic behavior versus time. The jet flapping phenomena are detailed numerically by the instantaneous streamlines contours and the vorticity magnitude contours within one period of oscillation. The heat transfer along the cavity walls is also periodic. Time average of mean Nusselt number is correlated according with some problem parameters.

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Unsteady phenomena of an oscillating turbulent jet flow inside a cavity: Effect of aspect ratio

Cited by 29 publications

References 37 publications

Dynamics of an oscillating turbulent jet in a confined cavity

Dynamics of an oscillating turbulent jet in a confined cavity

Effects of electromagnetic forcing on self-sustained jet oscillations

Numerical Investigations on Heat Transfer of Self-Sustained Oscillation of a Turbulent Jet Flow Inside a Cavity

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