Statistical characteristics of the diffusion of a chemically active additive in a turbulent mixing zone

1976 ◽  
Vol 16 (6) ◽  
pp. 878-886 ◽  
Author(s):  
A. F. Kurbatskii
Keyword(s):  
Turbulent Mixing ◽  
Statistical Characteristics ◽  
Mixing Zone ◽  
Active Additive

Dynamical behavior of the Richtmyer–Meshkov instability-induced turbulent mixing under multiple shock interactions

2017 ◽  
Vol 95 (8) ◽  
pp. 671-681 ◽  
Author(s):  
Tao Wang ◽  
Gang Tao ◽  
Jingsong Bai ◽  
Ping Li ◽  
Bing Wang ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Compression Wave ◽  
Dynamical Behavior ◽  
Characteristic Scale ◽  
Mixing Zone ◽  
Shock Interactions ◽  
Scale Parameters ◽  
Eddy Simulation ◽  
Negative Exponential ◽  
Multiple Shock

The dynamical behavior of Richtmyer–Meshkov instability-induced turbulent mixing under multiple shock interactions is investigated by large-eddy simulation. After the initial shockwave–interface interaction, the transmitted wave reverberates between the accelerated interface and the end-wall of the shock tube to form a process of multiple shock interactions. The turbulent mixing zone grows in a different manner under each of the impingements. After the initial shock, it grows as a power law of time. After the reshock and the impingement of the reflected rarefaction wave, it grows with time as a different negative exponential law. When the impingement of the reflected compression wave completes, it grows approximately in a linear fashion. The statistical quantities in the turbulent mixing zone evolve with time in a similar way under multiple impingements, and after the impingement of the reflected compression wave, they all decay asymptotically. Therefore, the turbulent mixing zone behaves in a statistically self-similar pattern. Even though the impingements of different waves result in different abrupt changes of the characteristic scale parameters of mixing turbulence, as a whole, the characteristic scales present a feature of growth, and the characteristic-scale Reynolds numbers present a feature of decay. The mixing flow is continuously anisotropic, yet the anisotropy weakens gradually. Therefore the development of turbulent mixing presents a trend of isotropy.

Statistical characteristics of turbulent mixing in spherical and cylindrical converging Richtmyer–Meshkov instabilities

2021 ◽  
Vol 928 ◽  
Author(s):  
Xinliang Li ◽  
Yaowei Fu ◽  
Changping Yu ◽  
Li Li
Keyword(s):  
Turbulent Mixing ◽  
Initial Perturbation ◽  
Great Influence ◽  
Mixing Layers ◽  
Statistical Characteristics ◽  
Computational Domain ◽  
Heavy Fluid ◽  
Node Number ◽  
Geometric Effect ◽  
Atwood Number

In this paper, the Richtmyer–Meshkov instabilities in spherical and cylindrical converging geometries with a Mach number of approximately 1.5 are investigated by using the high resolution implicit large eddy simulation method, and the influence of the geometric effect on the turbulent mixing is investigated. The heavy fluid is sulphur hexafluoride (SF6), and the light fluid is nitrogen (N2). The shock wave converges from the heavy fluid into the light fluid. The Atwood number is 0.678. The total structured and uniform Cartesian grid node number in the main computational domain is 20483. In addition, to avoid the influence of boundary reflection, a sufficiently long sponge layer with 50 non-uniform coarse grids is added for each non-periodic boundary. Present numerical simulations have high and nonlinear initial perturbation levels, which rapidly lead to turbulent mixing in the mixing layers. Firstly, some physical-variable mean profiles, including mass fraction, Taylor Reynolds number, turbulent kinetic energy, enstrophy and helicity, are provided. Second, the mixing characteristics in the spherical and cylindrical turbulent mixing layers are investigated, such as molecular mixing fraction, efficiency Atwood number, turbulent mass-flux velocity and density self-correlation. Then, Reynolds stress and anisotropy are also investigated. Finally, the radial velocity, velocity divergence and enstrophy in the spherical and cylindrical turbulent mixing layers are studied using the method of conditional statistical analysis. Present numerical results show that the geometric effect has a great influence on the converging Richtmyer–Meshkov instability mixing layers.

The Mixing of Turbulent Supersonic Fuel-Air Streams

1965 ◽  
Vol 16 (4) ◽  
pp. 377-387
Author(s):  
J. M. Forde
Keyword(s):  
Mach Number ◽  
Turbulent Mixing ◽  
Integral Form ◽  
Spreading Rate ◽  
External Flow ◽  
Supersonic Combustion ◽  
Mixing Zone ◽  
Mixing Conditions ◽  
Momentum Integral ◽  
Air Streams

SummaryAn integral part of the study of supersonic combustion is the investigation of supersonic turbulent mixing of dissimilar fluids. Experimental results obtained in the course of investigating the turbulent mixing zone between supersonic streams of CO3 and air are presented. Good correlation between observation and available theories has been obtained in terms of the parameter ξ=σy/x. The correlating parameter σ defines the spreading rate of the mixing zone. The available theories, though not developed for these specific conditions, are shown to be applicable to the turbulent mixing of supersonic streams.The correlating parameter σ was determined for three different combinations of internal and external flow Mach numbers. The values found for σ were 18, 16·3, 15·3 for constant external Mach number 1·62 and internal Mach number 1·62, 1·53, 1·47 respectively. The magnitudes of σ showed the expected trend, that is the higher value implies the least divergence of the mixing boundaries.The reasonable agreement with experiment and the simplicity of application of the momentum integral form of solution would appear to favour the use of this approach for the theoretical prediction of the mixing conditions.

Wave structure of turbulent mixing zone

1982 ◽  
Vol 42 (5) ◽  
pp. 500-505
Author(s):  
Ya. A. Vagramenko
Keyword(s):  
Turbulent Mixing ◽  
Wave Structure ◽  
Mixing Zone

Structure of the turbulent mixing zone on the boundary of two gases accelerated by a shock wave

1990 ◽  
Vol 26 (3) ◽  
pp. 315-320 ◽  
Author(s):  
E. E. Meshkov ◽  
V. V. Nikiforov ◽  
A. I. Tolshmyakov
Keyword(s):  
Shock Wave ◽  
Turbulent Mixing ◽  
Mixing Zone

Some Two-Dimensional Aspects of the Ejector Problem

1942 ◽  
Vol 9 (4) ◽  
pp. A151-A154 ◽  
Author(s):  
J. A. Goff ◽  
C. H. Coogan
Keyword(s):  
Turbulent Mixing ◽  
Rational Design ◽  
Two Dimensional ◽  
Mixing Zone ◽  
One Dimensional ◽  
Air Stream ◽  
The Right

Abstract Several investigators have attempted to analyze the performance of the ejector on a one-dimensional basis. Some doubt exists whether such analyses can lead to a rational ejector design because of the questionable validity of certain necessary assumptions. Recently, consideration has been given to the two-dimensional aspects of the problem, and while a rational design has not yet been evolved, the results attained seem to point in the right direction. The theory of turbulent mixing in jets, developed by Tollmien is used as the basis of the study reported in this paper. Tollmien’s analysis of the mixing zone produced by a homogeneous air stream issuing into still air of the same pressure and density is reviewed. The authors then extend the theory to allow for the possibility that the driving and driven fluids may have widely different densities.

Strain and Stratification Effects on the Rapid Acceleration of a Turbulent Mixing Zone

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Benoît-Joseph Gréa ◽  
Jérôme Griffond ◽  
Fabien Godeferd
Keyword(s):  
Turbulent Mixing ◽  
Density Field ◽  
Moving Frame ◽  
Mixing Zone ◽  
Mean Flow ◽  
Time Dynamics ◽  
Rayleigh Taylor Instability ◽  
The Mean ◽  
Two Parameters ◽  
Short Time

We consider the problem of a turbulent mixing zone (TMZ), initially submitted to coupled effects of axisymmetric strain and stratification, then subsequently accelerated. The TMZ grows in the latter stage due to a rapid mixing induced by the Rayleigh-Taylor instability. It is shown that the short time dynamics is simply determined by only two parameters expressing the structure of the turbulent density field, one related to the mixing, the other to the dimensionality of the flow. These quantities are studied by rapid distortion theory and by several homogeneous direct numerical simulations performed in the moving frame of the mean flow. The implications for modeling are discussed, the influence of anisotropy is presented.

scholarly journals Bulk turbulent transport and structure in Rayleigh–Taylor, Richtmyer–Meshkov, and variable acceleration instabilities

2003 ◽  
Vol 21 (3) ◽  
pp. 305-310 ◽  
Author(s):  
ANTOINE LLOR
Keyword(s):  
Turbulent Mixing ◽  
Fluid Model ◽  
Turbulent Transport ◽  
Model Testing ◽  
Turbulence Structure ◽  
Mixing Zone ◽  
Self Similar ◽  
Two Fluid Model ◽  
Directed Energy ◽  
Two Fluid

Directed energy and turbulence structure are shown to be crucial in understanding the growth of self-similar Rayleigh–Taylor and incompressible Richtmyer–Meshkov turbulent mixing zones. Averaging over the mixing zone is used to analyze the response of a modifiedk–ε model and a turbulent two-fluid model. Three different transport regimes are then identified by considering self-similar variable acceleration RT flows (SSVARTs), which appear as promising reference flows for model testing.

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