scholarly journals Evolution of the Rayleigh–Taylor instability in the mixing zone between gases of different densities in a field of variable acceleration

2003 ◽  
Vol 21 (3) ◽  
pp. 393-402 ◽  
Author(s):  
S.G. ZAYTSEV ◽  
V.V. KRIVETS ◽  
I.M. MAZILIN ◽  
S.N. TITOV ◽  
E.I. CHEBOTAREVA ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Compression Wave ◽  
Taylor Instability ◽  
Mixing Zone ◽  
Compression Waves ◽  
Accelerated Motion ◽  
And Shock Waves ◽  
Rayleigh Taylor Instability ◽  
Qualitative Distinction

The interaction of the mixing zone between two gases of different densities with compression waves and shock waves has been investigated. The characteristics of the mixing zone in which the Rayleigh–Taylor instability is developing have been analyzed. The evolution of the mixing zone volume and mass during the accelerated motion has been defined. A qualitative distinction in the evolution of the mixing zone under the influence of a continuous deceleration resulting from the interaction with the reflected compression wave—shockless deceleration—is revealed as compared to deceleration that is accompanied by appearance of a shock wave moving through the mixing zone—shock-induced deceleration.

scholarly journals Evolution of mixing zone under the influence of nonstationary compression wave

1999 ◽  
Vol 17 (4) ◽  
pp. 629-634
Author(s):  
S.G. ZAYTSEV ◽  
V.V. KRIVETS ◽  
S.N. TITOV ◽  
E.I. CHEBOTAREVA
Keyword(s):  
Experimental Investigation ◽  
Compression Wave ◽  
Gas Pressure ◽  
Taylor Instability ◽  
Inert Gas ◽  
Mixing Zone ◽  
Accelerated Motion ◽  
Hydrogen Mixture ◽  
Rayleigh Taylor Instability

In the present study we performed an experimental investigation of the Rayleigh–Taylor instability (RTI) in a mixing zone between two gases entrapped into accelerated motion by a nonstationary compression wave. Acceleration g was ∼1.5·107 cm/s2, Atwood numbers ranged from 0.04 to 0.77. A mixing zone was formed by an oxygen-hydrogen mixture and an inert gas (Ne, Ar, Kr, Xe) or SF6. The initial gas pressure was 0.5 atm. A specific feature of our experiment is compressibility of media tested and initially continuous interface between gases of different densities. The present work is a continuation of investigations on nonlinear, transition, and early turbulent stages of the RTI.

Shock waves in a liquid containing gas bubbles

1958 ◽  
Vol 243 (1235) ◽  
pp. 534-545 ◽  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Rarefaction Wave ◽  
Temperature Rise ◽  
Compression Wave ◽  
Liquid Mixture ◽  
Propagation Speed ◽  
Plane Wall ◽  
Shock Propagation ◽  
Wide Range

Considerations of continuity, momentum and energy together with an equation of state are applied to the propagation of plane shock waves in a gas + liquid mixture. The shock-wave relations assume a particularly simple form when the temperature rise across a shock, which is shown to be small for a very wide range of conditions, is neglected. In particular, a simple relation emerges between the shock propagation speed and the pressure on the high-pressure side of the shock, the density of the liquid and the relative proportions, by mass and volume, of gas and liquid in the mixture. It is shown from entropy considerations that a rarefaction wave cannot propagate itself without change of form, and it is argued that a compression wave can be expected to steepen into a shock wave. Consideration of the collision between two normal shock waves, moving in opposite directions, suggests that the strengths of the two shocks are unaltered by the interaction between them. This implies, in particular, that, when a shock impinges normally on a plane wall, the pressure ratio across the reflected shock is equal to that across the incident shock. When the mass ratio of gas to liquid in the mixture is allowed to tend to infinity, the various shock-wave relations for a mixture, derived with the temperature rise across the shock neglected, assume the same limiting form as the corresponding relations for a perfect gas when the ratio of specific heats tends to unity. The theoretical discussion has been illustrated by experiments with a small gas + liquid mixture shock tube. Samples of the records, obtained when the passage of a shock changes the amount of light transmitted through the mixture to a photoelectric cell, illustrate the steepening of a compression wave and the flattening of a rarefaction wave. Measurements confirm the theoretical relation for the propagation speed of shock waves. Reasonably good experi­mental confirmation is also reported of the theoretical predictions for the pressure which arises following the normal impact of a shock wave on a plane wall.

Self-similarity and internal structure of turbulence induced by Rayleigh–Taylor instability

1999 ◽  
Vol 399 ◽  
pp. 1-48 ◽  
Author(s):  
S. B. DALZIEL ◽  
P. F. LINDEN ◽  
D. L. YOUNGS
Keyword(s):  
Spatial Structure ◽  
Internal Structure ◽  
Initial Conditions ◽  
Salt Water ◽  
Concentration Field ◽  
Taylor Instability ◽  
Mixing Zone ◽  
Measured Velocity ◽  
Rigid Barrier ◽  
Rayleigh Taylor Instability

This paper describes an experimental investigation of mixing due to Rayleigh–Taylor instability between two miscible fluids. Attention is focused on the gravitationally driven instability between a layer of salt water and a layer of fresh water with particular emphasis on the internal structure within the mixing zone. Three-dimensional numerical simulations of the same flow are used to give extra insight into the behaviour found in the experiments.The two layers are initially separated by a rigid barrier which is removed at the start of the experiment. The removal process injects vorticity into the flow and creates a small but significant initial disturbance. A novel aspect of the numerical investigation is that the measured velocity field for the start of the experiments has been used to initialize the simulations, achieving substantially improved agreement with experiment when compared with simulations using idealized initial conditions. It is shown that the spatial structure of these initial conditions is more important than their amplitude for the subsequent growth of the mixing region between the two layers. Simple measures of the growth of the instability are shown to be inappropriate due to the spatial structure of the initial conditions which continues to influence the flow throughout its evolution. As a result the mixing zone does not follow the classical quadratic time dependence predicted from similarity considerations. Direct comparison of external measures of the growth show the necessity to capture the gross features of the initial conditions while detailed measures of the internal structure show a rapid loss of memory of the finer details of the initial conditions.Image processing techniques are employed to provide a detailed study of the internal structure and statistics of the concentration field. These measurements demonstrate that, at scales small compared with the confining geometry, the flow rapidly adopts self-similar turbulent behaviour with the influence of the barrier-induced perturbation confined to the larger length scales. Concentration power spectra and the fractal dimension of iso-concentration contours are found to be representative of fully developed turbulence and there is close agreement between the experiments and simulations. Other statistics of the mixing zone show a reasonable level of agreement, the discrepancies mainly being due to experimental noise and the finite resolution of the simulations.

scholarly journals Explosion waves and shock waves III-The initiation of detonation in mixtures of ethylene and oxygen and of carbon monoxide and oxygen

1935 ◽  
Vol 152 (876) ◽  
pp. 418-445 ◽  
Author(s):  
William Payman ◽  
H. Titman ◽  
Jocelyn Field Thorpe
Keyword(s):  
Shock Wave ◽  
Carbon Monoxide ◽  
Shock Waves ◽  
Detonation Wave ◽  
Wave Speed ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
And Shock Waves ◽  
Long Run ◽  
Detonating Gas

This series of papers has so far dealt mainly with non-maintained or partially maintained atmospheric shock waves, and only incidentally with the fully maintained "detonation" wave. It is generally accepted that the detonation wave in an explosive gas mixture is a shock wave produced by the rapid combustion of the mixture, sufficiently intense to cause almost instantaneous ignition of the gas through which it passes, and continuous maintained by the combustion thereby started. An account of some preliminary experiments, using the "wave-speed" camera to record the movement of the flame and of the invisible shock waves in front of the flame in gas mixtures prior to detonation, has already been given by one of us. Those experiments related mainly to hydrogen-oxygen and methane-oxygen mixtures whose aptitude to detonate may be regarded as moderate, for the continuation of the work, mixtures with oxygen have again been used, but a more readily detonating gas, ethylene, was chosen. Experiments were also made with carbon monoxide, because the flame usually requires a comparatively long run before detonation is established. These two gases have the advantage, not shared by hydrogen and methane, that their predetonation flames are sufficiently actinic for good records to be obtained by direct photography for comparison with corresponding "wave-speed" records. All gas mixtures used were saturated with water vapour.

Rayleigh-Taylor Instability of a Shock Accelerated Gas Water Interface

2001 ◽  
Author(s):  
Xiao-Liang Wang ◽  
Motoyuki Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Taylor Instability ◽  
Gravitational Acceleration ◽  
Water Interface ◽  
Wave Impact ◽  
Growth Coefficient ◽  
Video Images ◽  
Rayleigh Taylor Instability ◽  
Interfacial Plane

Abstract Rayleigh-Taylor instability at a gas-water interface has been investigated experimentally. Such instability was produced by accelerating a water column down a vertical circular tube employing shock wave impact. Accelerations from 50 to 100 times gravitational acceleration with fluid depths from 125 to 250 mm were studied. The resulting instability from small amplitude random perturbations was recorded and later analyzed using high-speed video images. Cavity formation was observed in the middle of the gas-water interface soon after the shock wave impact; bubbles and spikes then developed across the rest of the interfacial plane. Measurements of the growth coefficient of the bubbles and spikes show that they are nearly constant over different runs.

Effects of shock waves on Rayleigh-Taylor instability

2006 ◽  
Vol 13 (6) ◽  
pp. 062705 ◽  
Author(s):  
Yong-Tao Zhang ◽  
Chi-Wang Shu ◽  
Ye Zhou
Keyword(s):  
Shock Waves ◽  
Taylor Instability ◽  
Rayleigh Taylor Instability

Density Ratio and Entrainment Effects on Asymptotic Rayleigh–Taylor Instability

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Assaf Shimony ◽  
Guy Malamud ◽  
Dov Shvarts
Keyword(s):  
Numerical Study ◽  
Density Ratio ◽  
Three Dimensional ◽  
Growth Parameter ◽  
Taylor Instability ◽  
Mixing Zone ◽  
Mixing Process ◽  
Mixing Parameters ◽  
Rayleigh Taylor Instability ◽  
Self Similar

A comprehensive numerical study was performed in order to examine the effect of density ratio on the mixing process inside the mixing zone formed by Rayleigh–Taylor instability (RTI). This effect exhibits itself in the mixing parameters and increase of the density of the bubbles. The motivation of this work is to relate the density of the bubbles to the growth parameter for the self-similar evolution, α, we suggest an effective Atwood formulation, found to be approximately half of the original Atwood number. We also examine the sensitivity of the parameters above to the dimensionality (two-dimensional (2D)/three-dimensional (3D)) and to numerical miscibility.

scholarly journals Cherenkov-like shock waves associated with surpassing the light velocity barrier

1999 ◽  
Vol 77 (7) ◽  
pp. 561-569 ◽  
Author(s):  
G N Afanasiev ◽  
V G Kartavenko
Keyword(s):  
Shock Wave ◽  
Charged Particle ◽  
Shock Waves ◽  
Particle Velocity ◽  
Point Charge ◽  
Uniform Electric Field ◽  
Charge Motion ◽  
Light Velocity ◽  
Accelerated Motion ◽  
The Moment

The effects arising from the accelerated and decelerated motion of a point charge inside a medium are studied. The motion is manifestly relativistic and may be produced by a constant uniform electric field. It is shown that in addition to the bremsstrahlung and Cherenkov shockwaves, the electromagnetic shock wave arises when the charged-particle velocity coincides with the light velocity in the medium. For the accelerated motion, this shock wave, forming an indivisible entity with the Cherenkov shock wave, arrives after the arrival of the bremsstrahlung shock wave. For the decelerated motion the above shock wave detaches from the charge at the moment when its velocity coincides with the light velocity in the medium. This wave, existing even aftertermination of the charge motion, propagates with the velocity of light in the medium. It has the same singularity as the Cherenkov shock wave andis more singular than the bremsstrahlung shock wave.The space-time regions, where these shock waves exist, and conditions under which they can be observed are determined.PACS No.: 41.60

Rotational suppression of Rayleigh–Taylor instability

2002 ◽  
Vol 457 ◽  
pp. 181-190 ◽  
Author(s):  
G. F. CARNEVALE ◽  
P. ORLANDI ◽  
YE ZHOU ◽  
R. C. KLOOSTERZIEL
Keyword(s):  
Coriolis Force ◽  
Boussinesq Approximation ◽  
Taylor Instability ◽  
Vortex Rings ◽  
Mixing Zone ◽  
Rayleigh Taylor Instability ◽  
Atwood Number

It is demonstrated that the growth of the mixing zone generated by Rayleigh–Taylor instability can be greatly retarded by the application of rotation, at least for low Atwood number flows for which the Boussinesq approximation is valid. This result is analysed in terms of the effect of the Coriolis force on the vortex rings that propel the bubbles of fluid in the mixing zone.

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