Spanwise effects on instabilities of compressible flow over a long rectangular cavity

Sun, Yiyang; Taira, Kunihiko; Cattafesta, Louis N.; Ukeiley, Lawrence

doi:10.1007/s00162-016-0412-y

Cited by 22 publications

(26 citation statements)

References 31 publications

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“…The frequencies of the 2D eigenmodes agree well with the power spectral density. This observation has also been noted in other studies [34,40,41] that a use of mean flow as base state in stability analysis yields good prediction of temporal frequencies present in the unsteady flows.…”

Section: B Two-dimensional Instability and Resolvent Modessupporting

confidence: 83%

“…As β increases, the eigenmodes become more stable, and the eigenvalues exhibit a spreading pattern in terms of modal frequency. Among these eigenmodes, the least-stable ones are associated with low wavenumbers and low frequencies, which have been reported in previous studies [34]. These low wavenumber modes stem from centrifugal instabilities that are collocated with the recirculation region within the cavity.…”

Section: Three-dimensional Instability and Resolvent Modessupporting

confidence: 69%

“…Structured meshes with 7 and 14 million grid points are used for cases with Re D = 502 and 10 4 , respectively. The grid resolutions have been found to be sufficient to resolve the flow structures as discussed in our previous studies [23,34].…”

Section: B Compressible Laminar and Turbulent Open-cavity Flowsmentioning

confidence: 80%

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Resolvent Analysis of Compressible Laminar and Turbulent Cavity Flows

et al. 2020

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The present work demonstrates the use of resolvent analysis to obtain physical insights for open-cavity flows. Resolvent analysis identifies the flow response to harmonic forcing, given a steady base state, in terms of the response and forcing modes and the amplification gain. The response and forcing modes reveal the spatial structures associated with this amplification process. In this study, we perform resolvent analysis on both laminar and turbulent flows over a rectangular cavity with length-to-depth ratio of L/D = 6 at a free stream Mach number of M ∞ = 0.6 in a spanwise periodic setting. Based on the dominant instability of the base state, a discount parameter is introduced to resolvent analysis to examine the harmonic characteristics over a finite-time window. We first uncover the underlying flow physics and interpret findings from laminar flow at Re D = 502. These findings from laminar flow are extended to a more practical cavity flow example at a much higher Reynolds number of Re D = 10 4 . The features of response and forcing modes from the laminar and turbulent cavity flows are similar to the spatial structures from the laminar analysis. We further find that the large amplification of energy in flow response is associated with high frequency for turbulent flow, while the flow is

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Section: B Two-dimensional Instability and Resolvent Modessupporting

confidence: 83%

Section: Three-dimensional Instability and Resolvent Modessupporting

confidence: 69%

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Resolvent Analysis of Compressible Laminar and Turbulent Cavity Flows

et al. 2020

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“…The wake mode (at M ∞ = 0.6) dominates the flow with a large-scale vortex rolling up with an opposite sign vortex sheet being engulfed between the vortices. Details on the appearance of the wake mode are reported in Sun et al (2016a). For M ∞ = 0.9, the opposite sign vorticity patch pulled between the shedding vortices decreases, and the fluctuations over the cavity weaken.…”

Section: Flow Field Characteristicsmentioning

confidence: 99%

Biglobal instabilities of compressible open-cavity flows

et al. 2017

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The stability characteristics of compressible spanwise-periodic open-cavity flows are investigated with direct numerical simulation (DNS) and biglobal stability analysis for rectangular cavities with aspect ratios of L/D = 2 and 6. This study examines the behavior of instabilities with respect to stable and unstable steady states in the laminar regimes for subsonic as well as transonic conditions where compressibility plays an important role. It is observed that an increase in Mach number destabilizes the flow in the subsonic regime and stabilizes the flow in the transonic regime. Biglobal stability analysis for spanwise-periodic flows over rectangular cavities with large aspect ratio is closely examined in this study due to its importance in aerodynamic applications. Moreover, biglobal stability analysis is conducted to extract 2D and 3D eigenmodes for prescribed spanwise wavelengths λ/D about the 2D steady state. The properties of 2D eigenmodes agree well with those observed in the 2D nonlinear simulations. In the analysis of 3D eigenmodes, it is found that an increase of Mach number stabilizes dominant 3D eigenmodes. For a short cavity with L/D = 2, the 3D eigenmodes primarily stem from centrifugal instabilities. For a long cavity with L/D = 6, other types of eigenmodes appear whose structures extend from the aft-region to the mid-region of the cavity, in addition to the centrifugal instability mode located in the rear part of the cavity. A selected number of 3D DNS are performed at M ∞ = 0.6 for cavities with L/D = 2 and 6. For L/D = 2, the properties of 3D structures present in the 3D nonlinear flow correspond closely to those obtained from linear stability analysis. However, for L/D = 6, the 3D eigenmodes cannot be clearly observed in the 3D DNS, due to the strong nonlinearity that develops over the length of the cavity. In addition, it is noted that three-dimensionality in the flow helps alleviate violent oscillations for the long cavity. The analysis performed in this paper can provide valuable insights for designing effective flow control strategies to suppress undesirable aerodynamic and pressure fluctuations in compressible open-cavity flows.

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“…A unified perspective of instability in rotating Bödewadt, Ekman and von Kármán layers has been presented [7]. Instability of variable density flows in threedimensional containers has been analysed numerically [10,25] while a combined analytical and experimental effort discussed instability of compressible spanwise homogeneous cavity flow [31]. In the flow control theme, a linear feedback control approach was demonstrated to reduce the pressure drag of a D-shaped bluff body [6] and cluster-based control of a separating flow over a smoothly contoured ramp has been discussed [14].…”

Section: Contributions To the Present Volumementioning

confidence: 99%

Special issue on global flow instability and control

Theofilis

Colonius

2017

Theor. Comput. Fluid Dyn.

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This special issue is the second on the topic of "Global Flow Instability and Control," following the first in 2011. As with the previous special issue, the participants of the last two symposia on Global Flow Instability and Control, held in Crete, Greece, were invited to submit publications. These papers were peer reviewed according to the standards of the journal, and this issue represents a snapshot of the progress since 2011. In this preface, a sampling of important developments in the field since the first issue is discussed. A synopsis of the papers in this issue is given in that context.

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Spanwise effects on instabilities of compressible flow over a long rectangular cavity

Cited by 22 publications

References 31 publications

Resolvent Analysis of Compressible Laminar and Turbulent Cavity Flows

Resolvent Analysis of Compressible Laminar and Turbulent Cavity Flows

Biglobal instabilities of compressible open-cavity flows

Special issue on global flow instability and control

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