Evolution of the density self-correlation in developing Richtmyer–Meshkov turbulence

Tomkins, Christopher; Balachandran, Balakumar; Orlicz, Gregory C; Prestridge, Kathy; Ristorcelli, J. R.

doi:10.1017/jfm.2013.430

Cited by 48 publications

(42 citation statements)

References 38 publications

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“…In addition to density variance, the densityspecific volume correlation parameter b is an important alternative way to measure the mixture state of the HVDT and appears in turbulence mix models [4,29,30,31,32,33]: Figure 4 presents the evolution of b normalized by (Aρ) 2 ρ 2 . As it is seen, b behaves differently during explosive and saturated growths.…”

Section: Flow Evolution and Regimesmentioning

confidence: 99%

Variable-density buoyancy-driven turbulence with asymmetric initial density distribution

Aslangil

Livescu

Banerjee

2020

Physica D: Nonlinear Phenomena

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The effects of different initial density distributions on the evolution of buoyancy-driven homogeneous variable-density turbulence (HVDT) at low (0.05) and high (0.75) Atwood numbers are studied by using high-resolution direct numerical simulations. HVDT aims to mimic the acceleration-driven Rayleigh-Taylor and shock-driven Richtmyer-Meshkov instabilities and reveals new physics that arise from variable-density effects on the turbulent mixing. Here, the initial amounts of pure light and pure heavy flows are altered primarily to mimic the variable-density turbulence at the different locations of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities' mixing layers where the amounts of the mixing fluids are not equal. It is found that for the low Atwood number cases, the asymmetric initial density distribution has limited effects on both global and local flow evolution for HVDT. However, at high Atwood number, both global flow evolution and the local flow structures are strongly affected by the initial composition ratio. The flow composed of more light fluid reaches higher turbulent levels and the local statistics reach their fully-developed behavior earlier in the time evolution. During the late time decay, where most of the flow is well-mixed, all parameters become independent of the initial composition ratio for both low and high Atwood number cases.

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Section: Flow Evolution and Regimesmentioning

confidence: 99%

Variable-density buoyancy-driven turbulence with asymmetric initial density distribution

Aslangil

Livescu

Banerjee

2020

Physica D: Nonlinear Phenomena

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“…For cylindrical interfaces, a nitrocellulose membrane was used by Haas & Sturtevant (1987) to confine the test gas within the cylindrical volume. Later, the jet technique, developed by Jacobs (1992), became a primary way of forming a circular gas cylinder (Jacobs 1993;Tomkins et al 2008;Zhai et al 2014b), an elliptical gas cylinder (Zou et al 2010), two gas cylinders (Tomkins et al 2003), three gas cylinders (Kumar et al 2005) and a gas curtain (Orlicz et al 2009;Balakumar et al 2012;Tomkins et al 2013).…”

Section: Introductionmentioning

confidence: 99%

On the interaction of a planar shock with an polygon

Luo

Wang

et al. 2015

J. Fluid Mech.

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The interaction of a planar shock wave (M ≈ 1.2) with an SF 6 polygonal inhomogeneity surrounded by air is experimentally investigated. Six polygons including a square, two types of rectangle, two types of triangle, and a diamond are generated by the soap film technique developed in our previous work, in which thin pins are used as angular vertexes to avoid the pressure singularities caused by the surface tension. The evolutions of the shock-accelerated SF 6 polygons are captured by a high-speed schlieren system from which wave systems and the interface characteristics can be clearly identified. Both regular and irregular refraction phenomena are observed outside the volume, and more complex wave patterns, including transmitted shock, refracted shock, Mach stem and the interactions between them, are found inside the volume. Two typical irregular refraction phenomena (free precursor refraction, FPR, and free precursor von Neumann refraction, FNR) are observed and analysed, and the transition from FPR to FNR is found, providing the experimental evidence for the transition between different wave patterns numerically found in the literature. Combined with our previous work (Zhai et al., J. Fluid Mech., vol. 757, 2014, pp. 800-816), the reciprocal transitions between FPR and FNR are experimentally confirmed. The velocities and trajectories of the triple points are further measured and it is found that the motions of the triple points are self-similar or pseudo-stationary. Besides the shock dynamics phenomena, the evolutions of these shocked heavy polygonal volumes, which are quite different from the light ones, are captured and found to be closely related to their initial shapes. Specifically, for square and rectangular geometries, the different width-height ratios result in different behaviours of shock-shock interaction inside the volume, and subsequently different features for the outward jet and the interface. Quantitatively, the time-variations of the interface scales, such as the width and the normalized displacements of the edges, are obtained and compared with those from previous work. The comparison illustrates the superiority of the interface formation method and the significant effect of the initial interface shape on the interface features. Furthermore, the characteristics of the vortex core, including the velocity and vortex spacing, are experimentally measured, and the vortex velocity is compared with those from some circulation models to check the † Email address for correspondence: sanjing@ustc.edu.cn Interaction of planar shock waves with SF 6 polygons 367 validity of the models. The results in the present work enrich understanding of the shock refraction phenomenon and the database of research into Richtmyer-Meshkov instability (RMI).

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“…[12][13][14][15] RM instability has been studied for many years, [16][17][18][19] with recent emphasis on the subsequent turbulent mixing in a RM unstable fluid layer. [20][21][22] These studies show that variations in the initial conditions and Mach number lead to different flow features, turbulence statistics, and material mixing.…”

Section: Introductionmentioning

confidence: 99%

Density and velocity statistics in variable density turbulent mixing

Gerashchenko

Prestridge

2015

Journal of Turbulence

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We experimentally study variable-density mixing of miscible gases in an open-circuit wind tunnel using simultaneous particle image velocimetry and planar laser-induced fluorescence. Experiments of a high Atwood number (0.6) and low Atwood number (0.1) are performed to compare non-Boussinesq cases with the Boussinesq limit. The higher density gas is injected into the wind tunnel co-flow using a round jet configuration, and near-field and far-field measurements are performed to examine mixing in both momentum and buoyancy-dominated regimes. The effects of buoyancy are measurable and important in both large-scale mixing features and in turbulence quantities. The low Atwood number PDFs (probability density functions) show fast and uniform mixing. The high Atwood number PDFs of density have skewness towards the larger densities, indicating less mixing of the heavy fluid due to its inertia. The skewness in the density gradient PDFs at high Atwood number displays strong density local variations that can enhance mixing at molecular scales. Turbulent kinetic energy decreases with streamwise distance from the jet for low Atwood number but increases for high Atwood number due to larger buoyancy and density-driven shear. Over 3000 experimental realisations are used to calculate statistical characteristics of the mixing, including valuable and rarely given data such as Favre-averaged turbulent quantities: mass flux velocity, Reynolds stress, turbulent kinetic energy, and density-specific volume correlation. Buoyancy effects are observed in these quantities and the trends are compared qualitatively with direct numerical simulations.

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Evolution of the density self-correlation in developing Richtmyer–Meshkov turbulence

Cited by 48 publications

References 38 publications

Variable-density buoyancy-driven turbulence with asymmetric initial density distribution

Variable-density buoyancy-driven turbulence with asymmetric initial density distribution

On the interaction of a planar shock with an polygon

Density and velocity statistics in variable density turbulent mixing

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