... Rayleigh-Taylor Instability in Compressible Media ... 11 TITLE (Include Security Classification) Rayleigh-Taylor Instability in Compressible Media 12. ...
DTIC Science & Technology
... Accession Number : ADA138544. Title : Rayleigh-Taylor Instability in the Presence of a Stratified Shear Layer. Descriptive ...
. How does the flame accelerate? � Flame instabilities (Landau-Darrieus, Rayleigh-Taylor) � Interaction Rayleigh-Taylor Instability Rayleigh-Taylor � Buoyancy driven instability. � Large amounts of surface area
E-print Network
... Accession Number : ADA145491. Title : Rayleigh-Taylor Instability in Compressible Media. Descriptive Note : Interim rept. ...
... Title : RAYLEIGH-TAYLOR INSTABILITY IN LIQUID-METAL SYNCHRONOUS MHD GENERATORS AND METHODS OF STABILIZING IT,. ...
... Accession Number : ADA047402. Title : Nonlinear Theory of the Collisional Rayleigh-Taylor Instability in Equatorial Spread F. ...
). Produces ~ 0.6 M 56 Ni. How does the flame accelerate? � Flame instabilities (Landau-Darrieus, Rayleigh-Taylor as subgrid models. R us #12;Reactive Rayleigh-Taylor Instability Rayleigh-Taylor � Buoyancy driven
Size invariance of the granular Rayleigh-Taylor instability Jan Ludvig Vinningland,1, �istein scaling behavior of the granular Rayleigh-Taylor instability [Phys. Rev. Lett. 99, 048001 (2007.70.Qj Keywords: granular flow, gravitational instability, Rayleigh-Taylor ...
1 Modeling Rayleigh-Taylor Instability of a Sedimenting Suspension Arising in Direct Numerical gives rise to fingering which resembles Rayleigh-Taylor instability. The waves have a well- defined wavelength and growth rate which can be modeled as a conventional Rayleigh- ...
Center for Nonlinear Studies Rayleigh-Taylor Instability A heavy fluid (heavy) supported against gravity (g) by a lighter fluid (light) constitutes an unstable situation (Rayleigh-Taylor instability � RT of the turbulent Rayleigh-Taylor (RT) instability using ...
This report discusses topics on hydrodynamics instabilities in inertial confinement: linear analysis of Rayleigh-Taylor instability; ablation-surface instability; bubble rise in late-stage Rayleigh-Taylor instability; and saturation and multimode interactions in intermediate-stage ...
Energy Citations Database
LEMTA UMR CNRS 7563 PREPRINT Crossover between Rayleigh-Taylor Instability and turbulent cascading-Plateau, Rayleigh-Taylor or Kelvin-Helmholtz mechanism) or to turbulent cascades similar to Richardson-Plateau mechanism), acceleration of a droplet in the ambient air (Rayleigh-Taylor mechanism) and shear ...
Granular Rayleigh-Taylor instability Jan Ludvig Vinningland1 , �istein Johnsen1 , Eirik G. Flekk�y1 reported by V�ltz shares its main qualitative characteristics with the classical Rayleigh- Taylor glass plates. The internal dimensions of the cell are 56 mm � #12;Granular ...
Granular Rayleigh-Taylor instability Jan Ludvig Vinningland , �istein Johnsen , Eirik G. Flekk�y of spatial scale. Keywords: granular flow, Rayleigh-Taylor instability, pattern formation, size invariance to the classical Rayleigh-Taylor insta- bility [11] the coarsening process observed in ...
Nonideal Rayleigh-Taylor Mixing H. Lim , J. Iwerks , J. Glimm , and D. H. Sharp Department States of America Rayleigh-Taylor mixing is a classical hydrodynamic instability, which occurs when. Introduction Rayleigh-Taylor (RT) instability is a classical hydrodynamic instabil- ity [4, 34] which ...
/2 =exp(y/L) Inverted-density fluid Rayleigh-Taylor Instability Instability #12;"Bad Curvature" instability in plasmas Inverted Pendulum / Rayleigh-Taylor Instability Top view of toroidal plasma: plasma = heavy fluid
... Accession Number : AD0764119. Title : Viscous Effects in Rayleigh- Taylor Instability. Descriptive Note : Technical rept.,. ...
... INSTABILITIES, *RADIO WAVES, RAYLEIGH TAYLOR INSTABILITY, VERY LOW FREQUENCY, TSUNAMIS, IONOSONDES, EARTHQUAKES. ...
expansion, i.e., conditions arise for the growth of MHD Rayleigh-Taylor instability, which would lead, constituting a condition for the growth of MHD Rayleigh-Taylor instability. Development of MHD instabilities
Rayleigh-Taylor instability, the flow instability at a horizontal interface between two fluids with different densities, is demonstrated by a series of experiments that are suited for secondary and college level teaching. (c) 1999 American Institute of Physics.
The theoretical work previously done on Rayleigh Taylor instability in compressible fluids has been reviewed in a chapter written for the Encyclopedia of Fluid Mechanics, to be published by Gulf. The physical basis of the instability, the dependence of gr...
National Technical Information Service (NTIS)
The nonlinear behavior of the collisional Rayleigh-Taylor instability is studied in equatorial Spread F by including a dominant two-dimensional nonlinearity. It is found that on account of this nonlinearity, the instability saturates by generating damped ...
The saturation of the hydromagnetic Rayleigh-Taylor instability is caused by the reduction of driving current in the bubble region between the spikes formed as the instability develops. For short wavelengths, linear magnetic-field diffusion provides the n...
PLASMAS I. Simple picture of plasma microinstabilities Inverted pendulum Rayleigh-Taylor Magnetic-density fluid Rayleigh-Taylor Instability Instability #12;"Bad Curvature" instability in plasmas Inverted Pendulum / Rayleigh-Taylor Instability Top view ...
aspects of the numerical modelling of Rayleigh- Taylor instabilities will be discussed. The quality by a harmonic with wavelength 2 and amplitude 0.01 (compare table 3.4). Table 4.1 Rayleigh-Taylor instability x Analytical 0.05313 #12;Rayleigh-Taylor ...
Due to the sensitivity of Rayleigh-Taylor instabilities to initial conditions and due to the difficulty of forming well controlled cylindrical or spherical fluid interfaces, Rayleigh-Taylor experiments are often performed with simple, planar interfaces. R...
The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on a simple example of the Rayleigh-Taylor instability (w...
The evolution of the multimode Rayleigh-Taylor instability of nearly incompressible fluids, with density ratio r = 2, is investigated by means of two-dimensional hydrodynamic simulations. The study focuses on the effect of the initial perturbation on the ...
The compressible Rayleigh-Taylor instability of a supersonic accelerated contact discontinuity between two gases is studied by numerically solving the two-dimensional Euler equations. The computed solutions exhibit a complicated set of nonlinear waves com...
An account is provided of preliminary flow visualization observations made in an unstably stratified
NASA Technical Reports Server (NTRS)
... blast waves contain a contact surface (denoting the interface between the detonation products and the air) which is Rayleigh- Taylor instability. ...
... Theory and Experimental Observations of the Local Collisional Rayleigh-Taylor Instability in a Descending Equatorial Spread-F Ionosphere. ...
... than limited by the usual diffusion processes appears to be controlled by dynamic mixing processes arising from Rayleigh-Taylor instabilities at, for ...
studied. PACS numbers: 47.27.wj, 47.27.tb, 47.27.-i Keywords: Rayleigh-Taylor instability, turbulent mixing, Kolmogorov scaling law, subgrid models I. INTRODUCTION Rayleigh-Taylor (RT) instability occurs simulation with physical mass diffusion8,9 models the Banerjee-Andrews air-helium ...
studied. PACS numbers: 47.27.wj, 47.27.tb, 47.27.-i Keywords: Rayleigh-Taylor instability, turbulent mixing, Kolmogorov scaling law, subgrid models I. INTRODUCTION Rayleigh-Taylor (RT) instability occurs,15 models the Banerjee-Andrews air-helium Rayleigh-Taylor experiments1 . In this ...
motivated by supernova and laser experiments, and a two-dimensional Rayleigh-Taylor instability problem are used as numerical test problems. For the two-dimensional Rayleigh-Taylor instability problem-dimensional Rayleigh-Taylor instability problem 5,6,4 as our numerical ...
ZHANGy Abstract. In this paper, we establish a Front Tracking method to solve Rayleigh-Taylor (RT, 76M20. Key words and phrases. Front Tracking, Rayleigh-Taylor Instability, Richtmyer #12;RAYLEIGH-TAYLOR AND RICHTMYER-MESHKOV INSTABILITIES 3 method is also a factor to a ect the quality
. How does the flame accelerate? � Flame instabilities (Landau-Darrieus, Rayleigh-Taylor) � Interaction flame models. Look for scaling relations that will act as subgrid models. R us #12;Reactive Rayleigh-Taylor Instability Rayleigh-Taylor � Buoyancy driven ...
. How does the flame accelerate? � Flame instabilities (Landau-Darrieus, Rayleigh-Taylor) � Interaction. Look for scaling relations that will act as subgrid models. R us #12;Reactive Rayleigh-Taylor Instability Rayleigh-Taylor � Buoyancy driven instability. � Large ...
) resorts to instability dynamics (through refinements of Rayleigh-Plateau, Rayleigh-Taylor or Kelvin mechanism), acceleration of a droplet in the ambient air (Rayleigh-Taylor mechanism) and shear instability, that for an industrial nozzle, in the bag-breakup regime, Rayleigh-Taylor ...
scheme. Rayleigh-Taylor instability results from the application of a pressure gradient e.g., a gradient, the objective of this paper is to study the effect of shock waves on the development of the Rayleigh- Taylor and complicated smooth flow features, such as the problem of Rayleigh- ...
Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma N. Chakrabarti1 and G. S November 2002 � Accepted: 14 November 2002 Abstract. Collisional Rayleigh-Taylor (RT) instability and the perturbations. The influence of transverse velocity shear on Rayleigh- ...
was nearly flat, rather than the steep bottom- side, where Rayleigh-Taylor type instabilities are expected of free energy for ionospheric instability. The second was puzzling; Rayleigh-Taylor instabilities Pedersen conductivity existing in the E region. Layers produced by ...
Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter flu...
Convergent geometry Rayleigh-Taylor experiments have been performed with a 122-point detonation initiation system on cylinders having sinusoidal perturbations on the outer surface ranging from mode-6 to mode-36. Experiments were performed with various per...
- driven Rayleigh-Taylor (RT) instability develops. At later stages, this unstable flow becomes turbulent on immiscible Rayleigh- Taylor turbulence, submitted to Phys. Rev. Lett. 09/2004. Contact Information: Michael
); kkadau@lanl.gov T he Rayleigh-Taylor (RT) instability occurs when a heavy fluid lies on top of a light quickly by the wave number corresponding Figure 1-- Rayleigh-Taylor mixing of 100,589,840 atoms
comparative study of the turbulent Rayleigh-Taylor instability using high-resolution 3D numerical simulations. Rosner, A. Alexakis, J. Truran and W. Hilderbrandt 14 . "On the miscible Rayleigh-Taylor instability: two 7. Young, Y.-N. "Numerical simulation of double-diffusive convection and miscible ...
, a nondimensional number Rt ("Rayleigh Taylor number.") is defined, which is analogous to the Rayleigh number, Ra (Rayleigh-Taylor) instabilities. Ra-Rt-space is explored up to Ra = 30000 and Rt = 10000. Several f10w; after one Rayleigh-Taylor overturn the f10w may become stable, it may ...
and well studied Rayleigh-Taylor and Richtmyer-Meshkov instabilities which involve acceleration driven acceleration driven instabilities (Rayleigh-Taylor for continuous acceleration and Richtmyer) to obtain these results. Commonly, Rayleigh-Taylor mixing simulations show a factor of two or more
shown in Fig. 8. The initial configuration is similar to the classical Rayleigh-Taylor mixing problem-order methods #12;144 L. Shunn & F. Ham Figure 8. 2-D Rayleigh-Taylor instability. The left figures use node EOS evaluations 145 Figure 9. 2-D Rayleigh-Taylor instability at t = 5.2. (left ...
in an impulsively accelerated free stream, and the 3D immiscible Rayleigh-Taylor instability. Conclusions are given�128�128 with a domain size of 5D�5D�5D. 5.2. Rayleigh-Taylor Problem The Rayleigh-Taylor instability refers. Recently, the miscible Rayleigh-Taylor problem has been ...
and to validate this algorithm through the simulation of 3D Rayleigh-Taylor mixing of miscible fluids, ob- taining The acceleration of the bubble envelope in multimode Rayleigh-Taylor (RT) instability is postulated to depend Rayleigh-Taylor multimode mixing simulations, based on improved physcics modeling and on an ...
simulations (DNS) in two configurations: a) classical Rayleigh-Taylor instability using a 30723 data set [3,4], and b) an idealized triply periodic Rayleigh-Taylor flow named hereafter homogeneous Rayleigh-Taylor
) and turbulent combustion. Classic acceleration-driven instabilities (Rayleigh- Taylor for continuous we provide. In comparing the Smeeton-Youngs to the Mueschke-Andrews fresh-salt water Rayleigh-Taylor perturbations. Thus a central conclusion of our study is that there is nothing universal about ...
. Several numerical tests are performed to show the scheme capabilities. In particular, the viscous Rayleigh-Taylor density flows, Finite Element method, Finite Volume method, Rayleigh-Taylor instability. AMS Subject. This is the configuration chosen for the following numerical test (see subsection 3.2). 20 #12;3.2 Viscous ...
-density layer. We interpret the intrusions as products of a gravitational (Rayleigh-Taylor) instability where al. [2005, Figure 1]. B01303 BRODSKY ET AL.: RAYLEIGH-TAYLOR IN FAULTS 2 of 14 B01303 #12;material and included in this paper. B01303 BRODSKY ET AL.: RAYLEIGH-TAYLOR IN FAULTS 3 of 14 B01303 #12;is ...
... An approximate closed form expression for the growth rate of fluid instabilities in a multi-layered laser-driven target is presented. (Author). ...
The aim of this talk is to survey Rayleigh-Taylor instability, describing the phenomenology that occurs at a Taylor unstable interface, and reviewing attempts to understand these phenomena quantitatively.
DOE Information Bridge
... the long wavelength limit of several interchange instabilities (viz., Rayleigh-Taylor, E ... The scaling of these growth rates with wavenumber (k) and ...
Plasma arcs used to accelerate projectiles in railguns are examined to determine their susceptibility to the Rayleigh Taylor interchange instability. The model used is similar to that developed by Tsai, Liskow, and Wilcox, although a number of modificatio...
4, 2005 (DOI: will be inserted by hand later) Non-stationary Rayleigh-Taylor instability al.: Non-stationary Rayleigh-Taylor instability in supernova ejecta al. (Blondin et al. 2001 + C^r, (5) #12;X. Ribeyre et al.: Non-stationary Rayleigh-Taylor instability in supernova ...
.Willi, "Measurement and Simulation of Laser Imprinting and Consequent Rayleigh-Taylor growth", Phys.Rev.Lett.76, 1643 of three-dimensional Rayleigh-Taylor instability", Phys.Fluids A5, 1904 (1993); X.L.Li, "A numerical study of development of the #12;30 Rayleigh-Taylor instability in 3D ...
Rayleigh--Taylor instabilities of an accelerating plasma sheet are studied by application of normal mode analysis to the one-fluid magnetohydrodynamic equations. The equilibrium unperturbed states are determined by specifying the resistivity law of the current carrying plasma, although resistivity effects are neglected in the developing ...
A large number of volcanic features exist on Venus, ranging from tens of thousands of small domes to
... the stability of free capillary surfaces in rectangular containers against unfavorable disturbances (accelerations, i.e. Rayleigh-Taylor instability). ...
NASA Website
Several mechanisms that reduce the linear growth rate and severity of Rayleigh-Taylor instability in thin, inhomogeneous laser targets are discussed.
Nov 19, 2004 ... In this scenario the plasma instabilities that can occur during the accretion process (Rayleigh-Taylor, Kelvin-Helmoltz, ...
... The outer surface of the liner is driven by a plurality of radially-displaced free-pistons to eliminate high frequency Rayleigh-Taylor instability at the ...
... 1. INTRODUCTION ... relevance to such flows as those in lava lakes, the thermal ... The problem is illustrated in figure 1. Two layers of immiscible fluids ...
... a thin layer of very viscous fluid overlies a deep layer of less viscous, less dense fluid. ... (This conclusion also applies to fluids with power-law ...
... formulated. The new strategy should outperform traditional ones based solely on Rayleigh Taylor-type instability mechanisms. ...
... sunset ionospheric conductance near the South Atlantic Anomaly cause a decrease in growth rate for the generalized Rayleigh-Taylor instability. ...
... In particular, the turn-on conditions for the unmagnetized ion Rayleigh-Taylor instability are derived for both the fluid and kinetic regimes, as well as ...
... Abstract : Techniques have been developed to improve the uniformity of the laser focal profile to reduce the ablative Rayleigh Taylor instability, and ...
... Perturbations that seed Rayleigh-Taylor (RT) instability in laser-driven targets ... uniformity (laser imprint, surface ripple) are expected to oscillate. ...
... Abstract : Perturbations that seed Rayleigh-Taylor (RT) instability in laser-driven targets form during the early-time period. ...
... This process redistributes mass in the volume of the target, forming the feedout-generated seed for ablative Rayleigh-Taylor (RT) instability. ...
Natalia Vladimirova, University of Chicago; Michael Chertkov, T-13 T he Rayleigh-Taylor (RT) instability
This report discusses topics on hydrodynamics instabilities in inertial confinement: linear analysis of Rayleigh-Taylor instability; ablation-surface instability; bubble rise in late-stage Rayleigh-Taylor instability; and saturation and multimode interact...
structures in Rayleigh- Taylor mixing" Phys.Rev.Lett. 80, 3507 (1998) 7. F.H.Harlow, J.E.Welch, "Numerical.Zemach, "Rayleigh-Taylor instability and the use of conformal maps for ideal fluid flow" Jour.Comp.Phys. 51, 28 of three-dimensional Rayleigh-Taylor instability" ...
Numerical studies of the ablation-driven Rayleigh-Taylor instability in laser-accelerated targets show growth rates typically within a factor of 2 of the classical growth rate. The appearance of ''Kelvin-Helmholtz'' instability depends on the form of the initial perturbation and also on the laser ...
During the past year an experimental study of the shock-wave initiated Rayleigh-Taylor instability, also known as the Richtmeyer-Meshkov instability, has been initiated at the shock tube laboratories of the Graduate Aeronautical Laboratories, California I...
The existence Rayleigh-Taylor instabilities, in laser heated plasmas, is shown. By means of the acceleration of flat three-layered Au-Al-Au targets, a mixing zone, under the concept of Rayteigh-Taylor instabilities, is observed. The Al emission spectra is...
A lattice Boltzmann model for multicomponent fluid flows is used to simulate the two-dimensional Rayleigh-Taylor instability. The dynamical processes of the instability, varying from linear growth to mixing, have been simulated. The results agree with experiments, analytical studies, and other numerical simulations. {copyright} {ital ...
The authors investigate hydrodynamic instability of accelerating ionization fronts with two dimensional hydrodynamic simulations. When recombination in the ionized region is turned off, Rayleigh-Taylor instability is effective. Perturbation grows up with classical Rayleigh-Taylor growth rate. In the case with ...
This article presents a theory of these instabilities and potential modes of failure caused by them. Discussions are given for the following: small amplitude growth of the outside surface instability; and modes of failure resulting from nonlinear development of the inside surface instability.
A fully three-dimensional (3D) laser-matter interaction code is developed and used to investigate 3D mixing mechanisms in planar targets accelerated by single-sided laser illumination. While linear Rayleigh-Taylor growth rates from 3D perturbed simulations are identical to those obtained from 2D simulations, nonlinear evolution differs significantly. Vortex stretching alters ...
Potential theory permits ideal fluid dynamics to be formulated in terms of boundary motion. In two dimension, the flow can then be found using conformal mapping. The evolution of some Rayleigh--Taylor instabilities is calculated well into the large amplitude nonlinear regime. The Rayleigh--Taylor calculation for Atwood ratio unity is used as a prototype ...
Effects of temporal density variation and spherical convergence on the nonlinear bubble evolution of single-mode, classical Rayleigh-Taylor instability are studied using an analytical model based on Layzer's theory.
Magnetic Rayleigh-Taylor instability is addressed in compressible hydrostatic media. A full model is presented and compared to numerical results from a linear perturbation code. A perfect agreement between both approaches is obtained in a wide range of parameters. Compressibility effects are examined and substantial deviations from classical Chandrasekhar ...
The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh-Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the ...
NASA Astrophysics Data System (ADS)
, CCS-2; Jimmy Fung, Mark Kenamond, Edward Dendy, X-3 T he Rayleigh-Taylor instability (RTI) is a fluid-Mode Rayleigh-Taylor Instability: RAGE and FLAG Hydrocode Comparisons Marianne M. Francois, Robert B. Lowrie.I. Taylor (1950) [2]. Because of the RTI importance in many applications and because it has been widely
The validity of gradient-diffusion closures for modeling turbulent transport in multi-mode Rayleigh Taylor and reshocked Richtmyer Meshkov instability-induced mixing is investigated using data from three dimensional spectral/tenth-order compact difference...
The growth rates of the deceleration-phase Rayleigh-Taylor instability for imploding inertial confinement fusion capsules are calculated and compared with the results of numerical simulations. It is found that the unstable spectrum and the growth rates are significantly reduced by the finite ablation flow at the shell's inner surface. For typical ...
PubMed
The interface between two fluids of different density can experience instability when gravity acts normal to the surface. The relatively well known Rayleigh-Taylor (RT) instability results when the gravity is constant with a heavy fluid over a light fluid...
The Rayleigh-Taylor (R-T) Instability is studied in the Light Ion Beam (LIB) Inertial Confinement Fusion (ICF) pellet. The R-T instability is one of the problems in ICF. The nonuniform acceleration field and the radiation effects on the LIB-ICF pellet imp...
The instabilities induced by gravity on the interface separating two fluids of different densities (Rayleigh-Taylor instability), one of the two fluids being confined in a thin layer spread on a solid surface, is studied. In the simplest geometry (liquid ...
The purpose of this research program is to investigate fluid dynamic instabilities and mixing initiated by the interaction of shock waves with interfaces between light and heavy gases. In particular, the nonlinear stage of shock-initiated Rayleigh-Taylor instability (also known as the Richtmeyer-Meshkov ...
Here is a study about fluid flows (the hydrodynamic part of codes modeling the plasma dynamics) showing great gradients and unsteady flows (Rayleigh-Taylor, Richtmyer-Meshkov). The numerical resolution of these problems needs codes able to simulate the tr...
) T he Rayleigh-Taylor (RT) instability occurs when a heavy fluid lies on top of a light fluid cases Figure 1-- Rayleigh-Taylor mixing of 100,589,840 atoms by molecular dynamics of a heavy fluid (red
This is a report of the progress during the past year of the shock-tube study of the Richtmyer-Meshkov instability, initiated under the sponsorship of the Lawrence Livermore National Laboratory in September, 1982. The purpose of this research program, as stated in the original proposal, is: to investigate the nonlinear processes initiated by shock wave interaction with ...
Rayleigh-Taylor instability of a rotating compressible inviscid fluid was investigated. The coriolis force for unstable configuration decreases the critical wavelength of perturbations that give rise to Rayleigh modes, while for stable configurations it increases this critical wavelength. (auth)
Manifestations of both Rayleigh-Taylor instability and Karman vortices in atmospheric flows are recognized, and existing theory is applied to infer some values for the horizontal and vertical eddy transport coefficients for momentum, (K sub h) and (K sub ...
This paper is concerned with the singularities in inviscid two dimensional finite amplitude water waves and inviscid Rayleigh-Taylor instability. For the deep water gravity waves of permanent form, through a combination of analytical and numerical methods...
The feedout process transfers mass perturbations from the rear to the front surface of a driven target, producing the seed for the Rayleigh- Taylor (RT) instability growth. The feedout mechanism is investigated analytically and numerically for the case of...
Techniques have been developed to improve the uniformity of the laser focal profile to reduce the ablative Rayleigh Taylor instability, and to suppress the various laser plasma instabilities. There are now three ignition target design concepts that utiliz...
The model equations described in this paper are able to reproduce the qualitative behavior of the elastic-plastic Rayleigh-Taylor instability response seen in numerical experiments. Both elastic shear modulus and yield strength play important roles in the...
Modeling of the Three- Dimensional Viscous Rayleigh-Taylor Instability Boris J.P. Kaus and Yuri Y-difference/spectral method is used to model the 3D viscous Rayleigh-Taylor instability. Numerically calculated growth rate RAYLEIGH-TAYLOR INSTABILITY 0 0.005 0.01 0.015 0.02 ...
Computation of three-dimensional (3-D) Rayleigh--Taylor instability in compressible fluids is performed on a MIMD computer. A second-order TVD scheme is applied with a fully parallelized algorithm to the 3-D Euler equations. The computational program is implemented for a 3-D study of bubble evolution in the Rayleigh--Taylor instability ...
Linear theory of the ablative Rayleigh-Taylor instability in anisotropic diffusive materials is presented. This analysis indicates that enhancing diffusion in a plane transverse to the mean longitudinal flow can strongly reduce the growth of the instability. In the context of inertial confinement fusion, it is shown that anisotropic ...
The magnetic Rayleigh-Taylor (RT) instability has been predicted and observed to cause breakup of the plasma sheath in imploding Z-pinches. In this work we show that for the type of density profile encountered in strongly radiating pinches, instability at very short wavelengths grows to the non-linear stage and seeds progressively ...
The Rayleigh-Taylor instability at the interface in an immiscible two-component Bose-Einstein condensate is investigated using the mean field and Bogoliubov theories. Rayleigh-Taylor fingers are found to grow from the interface and mushroom patterns are formed. Quantized vortex rings and vortex lines are then generated around the mushrooms. The ...
A laminated ablator is explored as an alternative concept for stabilizing the ablative Rayleigh-Taylor instability which develops in inertial fusion targets. Experiments measuring the growth of the Rayleigh-Taylor instability of laminated planar foils are reported. Consistent with both theory and simulations, a significant reduction of ...
A numerical simulation of the nonlinear evolution of the collisional Rayleigh--Taylor instability using a set of equations appropriate for the equatorial F region ionosphere has been performed. The results show that the irregularities produced by the instability grow on the bottomside of the F region peak, as predicted by linear ...
A simplified analytic model is presented to describe the implosion of a plasma column by an azimuthal magnetic field of sufficient magnitude to drive a strong shock wave into the plasma. This model is employed together with buoyancy-drag-based models of nonlinear single-mode and turbulent multimode Rayleigh-Taylor (RT) growth to investigate the mixing process in such fast ...
A simplified analytic model is presented to describe the implosion of a plasma column by an azimuthal magnetic field of sufficient magnitude to drive a strong shock wave into the plasma. This model is employed together with buoyancy-drag-based models of nonlinear single-mode and turbulent multimode Rayleigh-Taylor growth to investigate the mixing process in such fast Z ...
Due to the sensitivity of Rayleigh-Taylor instabilities to initial conditions and due to the difficulty of forming well controlled cylindrical or spherical fluid interfaces, Rayleigh-Taylor experiments are often performed with simple, planar interfaces. Rayleigh-Taylor instability phenomena of practical interest, ...
Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These ...
We study a general multiple layer Rayleigh-Taylor instability problem for both compressible and incompressible inviscid fluids. Our main result is that many features of a multilayer system are universal, in the sense they do not depend on such details as the number of layers, their thicknesses, equations of state for the fluids, and equilibrium density ...
Two superimposed miscible liquids are separated by a diffuse boundary layer providing a steady transition of density. If the heavy fluid is on top of the light one, Rayleigh-Taylor-instabilities develop and cause a rapid interchange and eventually an inte...
The three-dimensional Rayleigh-Taylor (RT) instability was simulated with the Front Tracking code Fron
The use of axially-moving free-pistons to drive rotating liquid liners is described. The advantages of this approach include simple synchronism of piston motion to avoid low frequency Rayleigh-Taylor instability, a great reduction in the number of moving ...
A numerical analysis was carried out on the stability of targets designed to produce fusion energy gains close to 100 when irradiated with an appropriate heavy ion beam. To reach such performances, it was found that a high-Z radiation shield was necessary...
Growth rates of Rayleigh-Taylor modes, particularly those of long wavelength, are reduced at fluid interfaces in inhomogeneous laser-driven targets by the density gradients occurring naturally as a result of the acceleration. Growth rates can be reduced f...
Direct numerical simulation and large eddy simulations are powerful tools for studying turbulent flows. Unfortunately, they are computationally demanding in terms of run times, storage, and accuracy of the numerical method used. In particular, high order ...
The nonlinear evolution of the local collisional Rayleigh-Taylor instability in downward-moving equatorial F layers has been studied in a coordinated theoretical and experimental program dealing with actual conditions of bottomside spread F. For ambient bottomside electron density gradient scale lengths L=8 and 25 km, we find large percentage depletions ...
The evolution of the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities in the nonlinear regime of growth was investigated in indirect- drive experiments on the Nova laser. The RT experiments investigated the evolution of both single- and multi...
Recently, attention has focused on the effects of spherical convergence on the nonlinear phase of Rayleigh-Taylor growth. In particular, for instability growth on spherically converging interfaces, modifications to the predictions of the Layzer model for ...
this paper, we will illustrate this program by discussing its implementation in examples drawn from the authors' work and that of collaborators. This work as well as collateral work of others can be traced from the survey articles [2,3] and from [1]. 2 Rayleigh-Taylor Instability
Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, we present the first results from a computational study of such a system under d...
The evolution of the Rayleigh-Taylor (RT) instability in a compressible medium was investigated both at an accelerating embedded interface and at the ablation front in a new series of experiments on Nova. The x-ray drive generated in a hohlraum ablatively...
A modification of a boundary-integral method is used to study the single-scale Rayleigh-Taylor instability for arbitrary Atwood number. Smoothing the Green's function using vortex blobs suppresses singularities in the curvature and other modifications are...
A fully nonlinear sharp-boundary model of the ablative Rayleigh-Taylor instability is derived and closed in a similar way to the self-consistent closure of the linear theory. It contains the stabilizing effect of ablation and accurately reproduces the results of 2D DRACO simulations. The single-mode saturation amplitude, bubble and spike evolutions in the ...
A model for the nonlinear spectrum of the ablative Rayleigh-Taylor instability in laser-accelerated planar plasmas has been developed for a wide range of Froude numbers and scale sizes. It is found that the spectrum can be characterized by an inverse power law with spectral index of approximately 2 in the limit of small-wavenumber spectrum cutoffs and ...
The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on a simple example of the Rayleigh-Taylor instability (which occurs when a heavy fluid lies above a light fluid, and we perturb the ...
Convergent geometry Rayleigh-Taylor experiments have been performed with a 122-point detonation initiation system on cylinders having sinusoidal perturbations on the outer surface ranging from mode-6 to mode-36. Experiments were performed with various perturbation mode numbers, perturbation amplitudes, and ring accelerations. Feedthrough perturbation growth on the inner ...
In the frame of a CEA/US DOE collaboration, convergent experiments have been done on the Nova laser. Numerical simulations with our 2D Lagrangian code FCI2 led the analysis and correctly reproduced the experimental data. From single mode 2D perturbations, ablation front Rayleigh-Taylor instability growth is computed. Moderate and high convergence ratios ...
The study of the linear stage of the incompressible Rayleigh-Taylor instability in elastic-plastic solids is performed by considering thick plates under a constant acceleration that is also uniform except for a small sinusoidal ripple in the horizontal plane. The analysis is carried out by using an analytical model based on the Newton second law and it is ...
Traveling fronts can become transversally unstable either because of a diffusive instability arising when the key variables diffuse at sufficiently different rates or because of a buoyancy-driven Rayleigh-Taylor mechanism when the density jump across the front is statically unfavorable. The interaction between such diffusive and buoyancy ...
The homogenization of a heterogeneous mixture of two pure fluids with different densities by molecular diffusion and stirring induced by buoyancy generated motions is studied using Direct Numerical Simulations in two configurations: a) classical Rayleigh-Taylor instability using a 3072^3 data set (Cabot and Cook, Nature Phys. 2006, Livescu et al, J. Turb. ...
The Rayleigh-Taylor instability is a gravity driven instability of a contact surface between fluids of different densities. The growth of this instability is sensitive to numerical or physical mass diffusion. For this reason, high resolution of the contact discontinuity is particularly important. In this paper, we address this problem ...
Cryogenic direct-drive inertial confinement fusion (ICF) experiments at the Omega Laser Facility require 180 mg/cc resorcinol formaldehyde (RF) foam shells overcoated with a full density layer of CH. Surface perturbations on the overcoated shells can amplify Rayleigh-Taylor instabilities during target implosion. To study ...
A partial listing of topics includes: Nonlinear Rayleigh-Taylor instability; Gravitational tides in the Earth's core; Instability of a baroclinic boundary jet in a rotating fluid; Convection waves; Plate motion and thermal instability in the asthenosphere...
Direct numerical simulations of the line-tied Parker (or magnetic Rayleigh-Taylor) instability, based on the fully compressible ideal magnetohydrodynamic equations, are presented. In the intermediate nonlinear phase, the instability continues to grow exponentially in time and the plasma tends to develop convection-induced ...
The influence of temperature in the buoyancy driven Rayleigh-Taylor instability of reaction-diffusion fronts is investigated experimentally in Hele-Shaw cells. The acid autocatalysis of chlorite-tetrathionate reaction coupled to molecular diffusion yields exothermic planar reaction-diffusion fronts separating two miscible reactant and product solutions. ...
Two-dimensional (r-z) magnetohydrodynamic simulations of the electromagnetic implosion of metallic foil plasmas show, for certain initial configurations, a tendency to develop large-amplitude perturbations characteristic of the hydromagnetic Rayleigh-Taylor instability. These perturbations develop at the plasma magnetic field interface for plasma ...
Two dimensional experiments have been undertaken to study the phenomenon of liquid entrainment associated with interfacial hydrodynamic instabilities, specifically the Rayleigh Taylor instability. The current work is part of an effort to understand the phenomenon of Rayleigh ...
Preliminary results of three-dimensional simulations of compressible Rayleigh-Taylor instability and turbulent mixing in an ideal gas using the piecewise-parabolic method (PPM) (with and without molecular dissipation terms) are presented. Simulations with spatial resolutions up to 512{sup 3} were performed. Two types of convergence studies are presented. ...
Inertial confinement fusion (ICF) implosions, whether real or ideal, are subject to a variety of hydrodynamic instabilities that amplify small departures from spherical symmetry. Asymmetric implosions departing from spherical symmetry can lead to the breakup of the imploding shell or the creation of hydrodynamic turbulence. In an effort to understand the evolution of the ...
We present a novel experimental approach (rarefied supersonic pulse wind tunnel), which provides unprecedented access to interfacial instabilities and breakup over a wide range of Weber numbers. Key findings are that Rayleigh-Taylor instability alone is the active mechanism for free stream Weber numbers as low as 28 for low viscosity liquids and that ...
We report the formation of jet-like long spike in the nonlinear evolution of the ablative Rayleigh-Taylor instability (ARTI) experiments by numerical simulations. A preheating model ?(T) = ?SH[1 + f(T)], where ?SH is the Spitzer-H�rm (SH) electron conductivity and f(T) interprets the preheating tongue effect in the cold plasma ahead of the ablative front ...
Preliminary results of three-dimensional simulations of compressible Rayleigh-Taylor instabilities and turbulent mixing in an ideal gas using the piecewise-parabolic method (PPM) with and without molecular dissipation terms are presented. Simulations with spatial resolutions up to 512 were performed. Two types of convergence studies are presented. The ...
Magnetic flux emerges from the solar surface as dark filaments connecting small sunspots with opposite polarities. The regions around the dark filaments are often bright in X-rays and are associated with jets. This implies plasma heating and acceleration, which are important for coronal heating. Previous two-dimensional simulations of such regions showed that magnetic reconnection between the ...
We present some special steady state solutions of the nonlinear one- dimensional set of equations describing the Rayleigh-Taylor instability. This instability is believed to be one of the possible mechanisms responsible for equatorial spread F and we discuss the relevance of our results to some recent experimental observations.
We present the results of a series of detailed numerical simulations of the Rayleigh-Taylor instability in laser ablatively accelerated targets for a fairly wide range of initial conditions. It is shown that the Rayleigh-Taylor growth rate in an ablative ...
Ionospheric irregularities near the magnetic equator are studied. A numerical simulation is done for the generation and evolution of the ionospheric bubble based on the theory of the collisional Rayleigh-Taylor instability for two fluids, for the magnetic...
but less dense layered fluid (corn syrup�water solutions) in three different situations that are relevant Rayleigh�Taylor instability of a thin dense layer above a less dense but more viscous fluid (Chandrasekhar) for the Rayleigh�Taylor instability of a thin, dense, low-viscosity layer in a more viscous, less dense spherical
Techniques have been developed to improve the uniformity of the laser focal profile, to reduce the ablative Rayleigh-Taylor instability, and to suppress the various laser-plasma instabilities. There are now three direct-drive ignition target designs that utilize these techniques. Evaluation of these designs is still ongoing. Some of ...
Perturbations that seed Rayleigh-Taylor (RT) instability in laser- driven targets form during the early-time period. This time includes a shock wave transit from the front to the rear surface of the target, and a rarefaction wave transit in the opposite d...
A bubble merger model is presented for the nonlinear evolution of the Rayleigh-Taylor instability driven by a strong blast wave. Single bubble motion is determined by an extension of previous buoyancy-drag models extended to the blast wave driven case, an...
Two-dimensional Lagrangian hydrodynamics simulation techniques were used to study fluid instability in laser fusion pellets. A slab geometry comparison with classical Rayleigh-Taylor theory shows good agreement, as do other slab and spherical test problem...
The size scaling behavior of the granular Rayleigh-Taylor instability [J. L. Vinningland, Phys. Rev. Lett. 99, 048001 (2007)] is investigated experimentally, numerically, and theoretically. An upper layer of grains displaces a lower gap of air by organizing into dense fingers of falling grains separated by rising bubbles of air. The dependence of these ...
The size scaling behavior of the granular Rayleigh-Taylor instability [J. L. Vinningland , Phys. Rev. Lett. 99, 048001 (2007)] is investigated experimentally, numerically, and theoretically. An upper layer of grains displaces a lower gap of air by organizing into dense fingers of falling grains separated by rising bubbles of air. The dependence of these ...
It is vital to identify and control all perturbation sources that could trigger ablative Rayleigh-Taylor instability One obvious perturbation 'seed' is surface roughness computed perturbation growth, validated by experiments - Specification for allowable roughness of NIF ignition capsule' is based on But what about infernal ...
The problem of incomplete finite ion Larmor radius (FLR) stabilization of the magnetic curvature driven Rayleigh-Taylor instability (RTI) in low beta plasma with homogeneous ion temperature is investigated. For this purpose a model hydrodynamic description of nonlinear flute waves with arbitrary spatial scales compared to the ion Larmor radius is ...
The growth rate of the ablative Rayleigh-Taylor instability is approximated by gamma = square root[kg/(1 + kL)] - beta km/rho(a), where k is the perturbation wave number, g the gravity, L the density scale length, m the mass ablation rate, and rho(a) the peak target density. The coefficient beta was evaluated for the first time by measuring all quantities ...
A comparison of two-dimensional and three-dimensional high-resolution numerical large-eddy simulations of planar, miscible Rayleigh-Taylor instability flows are presented. The resolution of the three-dimensional simulation is sufficient to attain a fully turbulent state. A number of different statistics from the mixing region (e.g., growth rates, PDFs, ...
The highly nonlinear evolution of the single-mode Rayleigh-Taylor instability (RTI) at the ablation front of an accelerated target is investigated in the parameter range typical of inertial confinement fusion implosions. A new phase of the nonlinear bubble evolution is discovered. After the linear growth phase and a short constant-velocity phase, it is ...
Radiation pressure acceleration (RPA)[1] uses the high pressures of a high intensity laser pulses to accelerate low mass targets to high energy with potentially low energy spreads. However, simulations have shown susceptibility to the radiation pressure driven Rayleigh-Taylor instability [1,2]. Here we report on experiments performed with the VULCAN ...
The Rayleigh-Taylor (R-T) Instability is studied in the Light Ion Beam (LIB) Inertial Confinement Fusion (ICF) pellet. The R-T instability is one of the problems in ICF. The nonuniform acceleration field and the radiation effects on the LIB-ICF pellet implosion are studied by linear analyses. By means of these analyses the following results were obtained: ...
Indirectly driven, ablative Rayleigh-Taylor instability growth measurements in Ge-doped plastic foils were studied using face-on and side-on x-ray radiography. Laminated samples consisting of alternating layers of Ge-doped and undoped plastic and homogeneous Ge-doped foils were considered. We show for the first time that hydrodynamics do not depend upon ...
We analyze the expected experimental errors in a 5 Mbar peak pressure, Rayleigh-Taylor (RT) strength measurement in solid-state Ta to be performed on the National Ignition Facility in FY 2011. We also analyze the experimental errors for experiments on 1 Mbar Ta strength already being carried out at the Omega-EP laser facility. The strength is inferred by measuring its strong ...
We report on the behavior of a single-wavelength Rayleigh-Taylor flow at late times. The calculations were performed in a long square duct (lambda x lambda x 8lambda), using four different numerical simulations. In contradiction with potential flow theories that predict a constant terminal velocity, the single-wavelength Rayleigh-Taylor problem exhibits ...
The Rayleigh-Taylor instability for an interface separating two compressible media was investigated in the presence of a horizontal magnetic field. In incompressible fluids for the disturbances perpendicular to the direction of H, the magnetic field does not affect the development of Rayleigh- Taylor ...
A magnetic field gradient was used to draw down a low density paramagnetic fluid below a more dense fluid in a Hele-Shaw cell. On turning off the field a Rayleigh-Taylor instability was observed in situ, and the growth of the most unstable wave vector was measured versus time. A theory for the instability that permits different viscosities for two ...
The magnetopause separates the geomagnetic field from the interplanetary plasma and performs finite motions under the action of the solar wind pressure variable in time. Accelerations originating in this case result in that the necessary condition for the development of the Rayleigh-Taylor instability is formed at quite a definite motion phase. We can anticipate that the ...
We study the effects of polymer additives on turbulence generated by the ubiquitous Rayleigh-Taylor instability. Numerical simulations of complete viscoelastic models provide clear evidence that the heat transport is enhanced up to 50% with respect to the Newtonian case. This phenomenon is accompanied by a speed-up of the mixing layer growth. We give a ...
Observations of the line emission from the Crab Nebula indicate a structure consisting of dense filaments from which thin clumpy sheets of gas fan out radially. The jet feature noted by van den Bergh is one of these sheets. The sheets may have been created by the differential acceleration of filaments, or they may be the result of the formation of the dense filaments by the ...
We present state-of-the-art numerical simulations of a two-dimensional Rayleigh-Taylor instability for a compressible stratified fluid. We describe the computational algorithm and its implementation on the QPACE supercomputer. High resolution enables the statistical properties of the evolving interface that we characterize in terms of its fractal dimension ...
Using electron density profiles measured by the ALTAIR radar on 17 July 1979, we have performed global large scale size numerical simulations of the nonlinear evolution of the collisional Rayleigh-Taylor instability in the equatorial ionosphere. The ALTAI...
The well known drift cyclotron loss cone (DCLC) mode is shown to couple nonlinearly to a low frequency stable Rayleigh-Taylor mode through the process of nonlinear Landau damping. When the DCLC mode is linearly marginally stable, this coupling leads to an explosive instability, the time scale for which is in some agreement with the experimentally observed ...
The well-known drift cyclotron loss cone mode is shown to couple nonlinearly to a low frequency stable Rayleigh--Taylor mode through the process of nonlinear Landau damping. When the drift cyclotron loss cone mode is linearly marginally stable, this coupling leads to an explosive instability, the time scale for which is in some agreement with experimental ...
Shells 6 Andrews, Malcolm J. LANL Detailed Measurements at Texas A&M University of Turbulent Rayleigh of Shock-Initiated Flows 16 Cheng, Baolian LANL An Analytical Solution for the Growth Rate of a Multiple Shocked Fluid Mixing Layer 18 Demianov, A. Russia Rayleigh-Taylor and Richtmyer-Meshkov Instabilities
The authors report a study of the occurance of spread F, using data from studies in Jan. to Mar. 1984 and 1985 made using doppler radar and ionosondes. They report on the correlations of the height of the bottom of the F region, vertical drift velocity, and density gradients within electron distributions, with the occurances of spread F. They find the maximum growth rate of ...
The linear stability of the equilibrium of a thin liquid layer lying on a flat wall was studied. Usually this stability depends upon gravity (Rayleigh-Taylor instability) but not upon wall distance or wetting properties. Using the Cahn and Hilliard model ...
While many high energy density physics (HEDP) Rayleigh-Taylor and Richtmyer-Meshkov instability experiments have been fielded as part of basic HEDP and astrophysics studies, not one HEDP Kelvin-Helmholtz (KH) experiment has been successfully performed. He...
While many high energy density physics (HEDP) Rayleigh-Taylor and Richtmyer-Meshkov instability experiments have been fielded as part of basic HEDP and astrophysics studies, not one HEDP Kelvin-Helmholtz (KH) experiment has been successfully performed. Herein, a design for a novel HEDP x-ray driven KH experiment is presented along with supporting ...
this paper is to begin a systematic analysis of causes of these discrepancies. To do this, we summarize the results of previous RayleighTaylor instability studies, identify potential sensitive factors in Rayleigh-Taylor simulations, and report on new simulation results designed to quantify the effects of a number of these factors.
