Rayleigh–Taylor Instability With Varying Periods of Zero Acceleration

Aslangil, Denis; Farley, Zachary; Lawrie, Andrew; Banerjee, Arindam

doi:10.1115/1.4048348

Cited by 13 publications

(6 citation statements)

References 34 publications

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“…Limited attention has been given to experimental RTI studies that have coupled physics that may affect instability growth. These include (a) the coupled shear-buoyancy problem where RTI and KHI are competing [101], [113], and [133]; (b) the tilted rig RTI problem where the tilt gives rise to an angled (two-dimensional) interface concerning an acceleration history due to rockets (as in RR) attached at the top of the tank [69,71]; (c) suppression of RTI due to rotational effects [134,135]; (d) RTI with variable acceleration history [49,75,76,[136][137][138]; (e) RTI in solids where the material strength needs to be overcome before the growth of the instability [139][140][141]; and (f) compressible RTI in cylindrical geometry [142]. RTI experiments are extremely difficult to build, operate, run, and diagnose; as a result, the number of experimental studies pales in comparison to computational and modeling efforts.…”

Section: Conclusion and Some Future Opportunitiesmentioning

confidence: 99%

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

Banerjee

2020

Journal of Fluids Engineering

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The focus of experiments and the sophistication of diagnostics employed in Rayleigh Taylor Instability (RTI) induced mixing studies have evolved considerably over the past seven decades. The first theoretical analysis by Taylor and experimental results by Lewis on RTI in 1950 examined two-dimensional, single-mode RTI using conventional photographic techniques. Over the next 70 years, several experimental designs have been used to creating an RTI unstable interface between two materials of different densities. These early experiments though innovative, were arduous to diagnose and provided little information on the internal, turbulent structure and initial conditions of the RT mixing layer. Coupled with the availability of high-fidelity diagnostics, the experiments designed and developed in the last three decades allow detailed measurements of various turbulence statistics that have allowed broadly to validate and verify late-time non-linear models and mix-models for buoyancy-driven flows. Besides, they have provided valuable insights to solve several long-standing disagreements in the field. This review serves as an opportunity to discuss the understanding of the RTI problem and highlight valuable insights gained into the RTI driven mixing process through experiments. For the current review, the focus is on low to high Atwood number (> 0.1) experiments.

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Section: Conclusion and Some Future Opportunitiesmentioning

confidence: 99%

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

Banerjee

2020

Journal of Fluids Engineering

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“…We have formulated a set of generalized, scale resolving (SR) variables for variable density turbulence, b, a i , T i j , in equations (29)(30)(31), which are presented and discussed in section II. These variables are written as inner products of the fluctuations of a quantity q of the form qi (x) ≡ q i (ξ ) − u i (x),…”

Section: Discussionmentioning

confidence: 99%

“…Aslangil et al [25], [12] discuss how the identification of these regimes makes it possible to draw parallels between HVDT and more complex VDT flows, such as Rayleigh-Taylor Instability (RTI) 26,27 , RTI under variable-acceleration [28][29][30][31] , Richtmyer-Meshkov Instability (RMI) 32,33 , VD mixing layers 34 , and VD jets 35 , among others. Recent reviews of some of these flows and the relevant VD processes involved may be found in [31, 36, and 37].…”

Section: Flow Descriptionmentioning

confidence: 99%

“…To illustrate these ideas, we perform diagnostics of the SR-equivalent of RANS variables that are used to investigate 12,18,23,24,34 and model 11,[13][14][15] variable density turbulence, namely the density-specific volume covariance b, the turbulent mass-flux velocity a i , the Reynolds stress T i j , and the resolved kinetic energy k r , defined in equations ( 29), (30), (31), (55), respectively, using theory and diagnostics from DNS of homogeneous variable density turbulence at times that are representative of different dynamical regimes in this flow.…”

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confidence: 99%

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Filtering, averaging and scale dependency in homogeneous variable density turbulence

Saenz,

Aslangil,

Livescu

2020

Preprint

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We investigate relationships between statistics obtained from filtering and from ensemble or Reynolds-averaging turbulence flow fields as a function of length scale. Generalized central moments in the filtering approach are expressed as inner products of generalized fluctuating quantities, q (ξ , x) = q(ξ ) − q(x), representing fluctuations of a field q(ξ ), at any point ξ , with respect to its filtered value at x. For positive-definite filter kernels, these expressions provide a scale-resolving framework, with statistics and realizability conditions at any length scale. In the small-scale limit, scale-resolving statistics become zero.In the large-scale limit, scale-resolving statistics and realizability conditions are the same as in the Reynolds-averaged description. Using direct numerical simulations (DNS) of homogeneous variable density turbulence, we diagnose Reynolds stresses, T i j , resolved kinetic energy, k r , turbulent mass-flux velocity, a i , and density-specific volume covariance, b, defined in the scale-resolving framework. These variables, and terms in their governing equations, vary smoothly between zero and their Reynolds-averaged definitions at the small and large scale limits, respectively. At intermediate scales, the governing equations exhibit interactions between terms that are not active in the Reynolds-averaged limit. For example, in the Reynolds-averaged limit, b follows a decaying process driven by a destruction term; at intermediate length scales it is a balance between production, redistribution, destruction, and transport, where b grows as the density spectrum develops, and then decays when mixing becomes strong enough. This work supports the notion of a generalized, length-scale adaptive model that converges to DNS at high resolutions, and to Reynolds-averaged statistics at coarse resolutions. a) Invited for Physics of Fluids special issue in memory of Edward E.

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“…Aslangil et al explore RTI-induced mixing for zero acceleration with variable periods. The results were compared with the case of classical constant gravity, when acceleration is removed for either some indefinite period or intermediate period [79]. Sabet et al demonstrated that mixing properties of fluids influenced drastically due to viscosity contrast between two miscible fluids under the destabilization effect of RTI [80].…”

Section: Review Of the Current Statusmentioning

confidence: 99%

Plasma Waves and Rayleigh–Taylor Instability: Theory and Application

Singh¹,

Vidhani²,

Yogi³

et al. 2023

Plasma Science - Recent Advances, New Perspectives and Applications

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The presence of plasma density gradient is one of the main sources of Rayleigh–Taylor instability (RTI). The Rayleigh–Taylor instability has application in meteorology to explain cloud formations and in astrophysics to explain finger formation. It has wide applications in the inertial confinement fusion to determine the yield of the reaction. The aim of the chapter is to discuss the current status of the research related to RTI. The current research related to RTI has been reviewed, and general dispersion relation has been derived under the thermal motion of electron. The perturbed densities of ions and electrons are determined using two fluid approach under the small amplitude of oscillations. The dispersion equation is derived with the help of Poisson’s equation and solved numerically to investigate the effect of various parameters on the growth rate and real frequency. It has been shown that the real frequency increases with plasma density gradient, electron temperature and the wavenumber, but magnetic field has opposite effect on it. On the other hand, the growth rate of instability increases with magnetic field and density gradient, but it decreases with electron temperature and wave number.

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Rayleigh–Taylor Instability With Varying Periods of Zero Acceleration

Cited by 13 publications

References 34 publications

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

Filtering, averaging and scale dependency in homogeneous variable density turbulence

Plasma Waves and Rayleigh–Taylor Instability: Theory and Application

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