OJFD  Vol.5 No.2 , June 2015
Mixing Efficiency across Rayleigh-Taylor and Richtmeyer-Meshkov Fronts
ABSTRACT
Mixing generated by gravitational acceleration and the role of local turbulence measured through multifractal methods is examined in numerical experiments of Rayleigh-Taylor and Richtmyer-Meshkov driven front occurring at density interfaces. The global advance of the fronts is compared with laboratory experiments and Nusselt and Sherwood numbers are calculated in both large eddy simulation (LES) and kinematic simulation KS models. In this experimental method, the mixing processes are generated by the evolution of a discrete set of forced turbulent plumes. We describe the corresponding qualitative results and the quantitative conclusions based on measures of the density field and of the height of the fluid layers. We present an experimental analysis to characterize the partial mixing process. The conclusions of this analysis are related to the mixing efficiency and the height of the final mixed layer as functions of the Atwood number, which ranges from 9.8 × 10−3 to 1.34 × 10−1.

Cite this paper
Redondo, J. , Gonzalez-Nieto, P. , Cano, J. and Garzon, G. (2015) Mixing Efficiency across Rayleigh-Taylor and Richtmeyer-Meshkov Fronts. Open Journal of Fluid Dynamics, 5, 145-150. doi: 10.4236/ojfd.2015.52017.
References
[1]   Linden, P.F. and Redondo, J.M. (1991) Molecular Mixing in Rayleigh-Taylor Instability. Part 1. Global Mixing. Physics of Fluids, 5, 1267-1274.
http://dx.doi.org/10.1063/1.858055

[2]   Linden, P.F., Redondo, J.M. and Youngs, D. (1994) Molecular Mixing in Rayleigh-Taylor Instability. Journal of Fluid Mechanics, 265, 97-124.
http://dx.doi.org/10.1017/S0022112094000777

[3]   Castilla, R. and Redondo, J.M. (2000) Numerical Simulations of Particle Diffusion in Isotropic and Homogeneous Turbulent Flows. In: Redondo, J.M. and Babiano, A., Eds., Turbulent Diffusion in the Environment, 69-76.

[4]   Taylor, G.I. (1950) The Instability of Liquid Surfaces When Accelerated in a Direction Perpendicular to Their Planes. Proceedings of the Royal Society of London, Series A, Mathematical and Physical Sciences, 201, 192-196.
http://dx.doi.org/10.1098/rspa.1950.0052

[5]   Chandrasekar, S. (1961) Hydrodynamic and Hydromagnetc Stability. Dover Ed., New York.

[6]   Read, K.I. (1984) Experimental Investigation for Turbulent Mixing by Rayleigh-Taylor Instability. Physica, D12, 45-48.
http://dx.doi.org/10.1016/0167-2789(84)90513-x

[7]   Youngs, D.L. (1994) Numerical Simulation of Turbulent Mixing by Rayleigh-Taylor and Richtmyer-Meshkov Instabilities. Laser and Particle Beams, 12, 725-750.
http://dx.doi.org/10.1017/S0263034600008557

[8]   Castilla, R., Redondo, J.M., Gamez-Monterol, P.J. and Babiano, A. (2007) Particle Dispersion in Two Dimensional Turbulence: A Comparison with 2D Kinematic Simulation. Nonlinear Processes in Geophysics, 14, 139-151.
http://dx.doi.org/10.5194/npg-14-139-2007

[9]   Fung, J.C.H. and Vassilicos, J.C. (2007) Two-Particle Dispersion in Turbulentlike Flows. Phisical Review E, 57, 1677-1690.
http://dx.doi.org/10.1103/PhysRevE.57.1677

[10]   Redondo, J.M. (1990) The Structure of Density Interfaces. Ph. D. Thesis, Cambridge University, Cambridge.

 
 
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