Turbulent Mixing and Transition Criteria of Flows Induced by Hydrodynamic Instabilities

Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM), and Kelvin-Helmholtz (KH) instabilities play an important role in inertial confinement fusion (ICF) as well as a wide range of geophysical, astrophysical, and engineering flows. Much effort has been expended to model the linear and nonlinear regimes of these mixing instabilities. The greatest impact of turbulent mixing, however, occurs after these instability-induced flows have already transitioned to turbulence. An important outstanding question is whether one can define a metric to indicate whether the fundamental physics of the flows of interest has been captured and suitably resolved using the tools available to the researcher. These significant issues have not been adequately covered in previous tutorials, but a number of recent developments including the rapid advancement of supercomputing power and experimental diagnostics tools are now providing new possibilities. This tutorial talk brings these advancements together, showing how theories, experiments, simulations, and engineering models have been synthesized to describe the physics of turbulent mixing process. This talk stresses the dependence on initial condition, as well as both density differences and the characteristic anisotropy, emphasizing the key differences between the two- and three-dimensional mixing layers. The unique problems of astrophysical and high-energy-density physics applications and efforts to model these will be highlighted.

Zhou, Y., Rayleigh-Taylor and Richtmyer-Meshkov instability induced flow, turbulence,

and mixing, I. Physics Reports, 720-722. (2017) pp. 1-136.

Zhou, Y., Rayleigh-Taylor and Richtmyer-Meshkov instability induced flow, turbulence,

and mixing, II. Physics Reports, 723-725. (2017) pp. 1-160.