Laser-generated Richtmyer–Meshkov and Rayleigh–Taylor instabilities. III. Near-peripheral region of Gaussian spot

Lugomer, Stjepan

doi:10.1017/s0263034617000611

Cited by 9 publications

(11 citation statements)

References 29 publications

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“…The velocity field is potential in the bulk, and vortical structures are produced by shear at the interface. These results are in excellent qualitative agreement with available observations [20,[23][24][25][26][27][28][29][30][31][32][33].…”

Section: Discussionsupporting

confidence: 91%

“…Our analysis has investigated the dependence of RT-to-RM transition on the fluid density ratio and on the acceleration strength for both linear and nonlinear dynamics, it agrees qualitatively with available observations [20,[23][24][25][26][27][28][29][30][31][32][33], and elaborates extensive theory benchmarks, not diagnosed before, for future experiments and simulations. These include, for instance, the velocity and pressure fields, the interface morphology and bubble/spike curvatures, the interfacial shear and its link to the bubble/spike velocities and curvatures, the spectral properties of the velocity and pressure, along with the interface growth and growth rate.…”

Section: Discussionsupporting

confidence: 81%

“…Yet, the shape of nonlinear RT bubble is curved because it moves steady, and that of RM bubble is flattened because it decelerates. These results achieved excellent agreement with experiments and simulations [6,7,18,20,24,[43][44][45]. Group theory approach further finds that the invariant, correlation, scaling and spectral properties of RT mixing depart substantially from those of canonical turbulence, and that RT mixing with constant acceleration keeps order even at high Reynolds numbers, ∼ 3.2x10 6 .…”

Section: Introductionsupporting

confidence: 73%

“…And hence achieve a better understanding of RT/ RM relevant processes in Nature and technology [8][9][10][11][12][13][14][15][16][17][18]. We can also help to improve numerical modeling and experimental diagnostics of the interfacial dynamics of fluids, plasmas and materials [20,[23][24][25][26][27][28][29][30][31][32][33].…”

Section: Discussionmentioning

confidence: 99%

“…Non-equilibrium RT/RM dynamics is challenging to study [5][6][7][8][17][18][19]. In experiment, the challenges are due to the sensitive and transient character of RTI/RMI, and the unusually tight requirements on the flow implementation and control [23][24][25][26][27][28]. Simulations must accurately track interfaces and capture small-scale processes, as well as apply highly accurate methods, massive computations and a large span of spatial and temporal scales [29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

On Rayleigh-Taylor and Richtmyer-Meshkov Dynamics With Inverse-Quadratic Power-Law Acceleration

Hill

Abarzhi

2022

Front. Appl. Math. Stat.

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Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities occur in many situations in Nature and technology from astrophysical to atomic scales, including stellar evolution, oceanic flows, plasma fusion, and scramjets. While RT and RM instabilities are sister phenomena, a link of RT-to-RM dynamics requires better understanding. This work focuses on the long-standing problem of RTI/RMI induced by accelerations, which vary as inverse-quadratic power-laws in time, and on RT/RM flows, which are three-dimensional, spatially extended and periodic in the plane normal to the acceleration direction. We apply group theory to obtain solutions for the early-time linear and late-time nonlinear dynamics of RT/RM coherent structure of bubbles and spikes, and investigate the dependence of the solutions on the acceleration’s parameters and initial conditions. We find that the dynamics is of RT type for strong accelerations and is of RM type for weak accelerations, and identify the effects of the acceleration’s strength and the fluid density ratio on RT-to-RM transition. While for given problem parameters the early-time dynamics is uniquely defined, the solutions for the late-time dynamics form a continuous family parameterised by the interfacial shear and include special solutions for RT/RM bubbles/spikes. Our theory achieves good agreement with available observations. We elaborate benchmarks that can be used in future research and in design of experiments and simulations, and that can serve for better understanding of RT/RM relevant processes in Nature and technology.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 81%

Section: Introductionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On Rayleigh-Taylor and Richtmyer-Meshkov Dynamics With Inverse-Quadratic Power-Law Acceleration

Hill

Abarzhi

2022

Front. Appl. Math. Stat.

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Turbulent mixing and transition criteria of flows induced by hydrodynamic instabilities

et al. 2019

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In diverse areas of science and technology, including inertial confinement fusion (ICF), astrophysics, geophysics, and engineering processes, turbulent mixing induced by hydrodynamic instabilities is of scientific interest as well as practical significance. Because of the fundamental roles they often play in ICF and other applications, three classes of hydrodynamic instability-induced turbulent flows—those arising from the Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-Helmholtz instabilities—have attracted much attention. ICF implosions, supernova explosions, and other applications illustrate that these phases of instability growth do not occur in isolation, but instead are connected so that growth in one phase feeds through to initiate growth in a later phase. Essentially, a description of these flows must encompass both the temporal and spatial evolution of the flows from their inception. Hydrodynamic instability will usually start from potentially infinitesimal spatial perturbations, will eventually transition to a turbulent flow, and then will reach a final state of a true multiscale problem. Indeed, this change in the spatial scales can be vast, with hydrodynamic instability evolving from just a few microns to thousands of kilometers in geophysical or astrophysical problems. These instabilities will evolve through different stages before transitioning to turbulence, experiencing linear, weakly, and highly nonlinear states. The challenges confronted by researchers are enormous. The inherent difficulties include characterizing the initial conditions of such flows and accurately predicting the transitional flows. Of course, fully developed turbulence, a focus of many studies because of its major impact on the mixing process, is a notoriously difficult problem in its own right. In this pedagogical review, we will survey challenges and progress, and also discuss outstanding issues and future directions.

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Mixing driven by transient buoyancy flows.II. Flow dynamics

2021

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The chaotic advection of the interface between two miscible liquids inside a closed cavity, generated by a damped oscillatory buoyancy-driven (BD) regular flow field, is investigated experimentally for BD mixing. The Lagrangian history of interface motion, determined using the planar laser-induced fluorescence and the photographic full-field view method, is contrasted against the Eulerian flow field measured from particle image velocimetry. Chaotic advection stretches and folds the interface at an early stage to produce an asymmetric pairwise Rayleigh–Taylor (RT) morphology (RTM) structure from long wavelength RT instability and short-time Richtmyer–Meshkov instability and its fractal interface structure at a high impulsive-Reynolds number. The mechanism of folding, from global bifurcation of the flow field, caused by a hyperbolic point, served as an organizing center for multiple vortex interactions. The intermediate-stage kinematics of the RTM structure exhibits RT mixing and shows unfolding of the lamellar structure from the net effect of stretching, folding, and molecular diffusion prior to its breakdown; and it has a probabilistic outcome of exhibiting topological transitions through a breakup of the RTM structure in phase space from necking singularity and pinch-off, indicating sensitivity to the initial conditions. The effectiveness of mixing determined from mixing efficiency is contrasted against mechanical and lamellar models of mixing. The determination of topological entropy, from an approximate Gaussian distribution of the interface length stretch, yields time scale for information decay comparable to time scale for which a low-order horseshoe map emerges from flow, indicating local chaos of the interface. The late-stage breakdown of the RTM structure from internal and wall collision drives the interaction between advection and diffusion, which indicates that critical mixing time scales as the logarithmic of Peclet number, comparable to time-periodic sine flow and blinking vortex flow chaotic mapping models.

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Laser-generated Richtmyer–Meshkov and Rayleigh–Taylor instabilities. III. Near-peripheral region of Gaussian spot

Cited by 9 publications

References 29 publications

On Rayleigh-Taylor and Richtmyer-Meshkov Dynamics With Inverse-Quadratic Power-Law Acceleration

On Rayleigh-Taylor and Richtmyer-Meshkov Dynamics With Inverse-Quadratic Power-Law Acceleration

Turbulent mixing and transition criteria of flows induced by hydrodynamic instabilities

Mixing driven by transient buoyancy flows.II. Flow dynamics

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