Progress on Understanding Rayleigh–Taylor Flow and Mixing Using Synergy Between Simulation, Modeling, and Experiment

Abstract

Simultaneous advances in numerical methods and computing, theoretical techniques, and experimental diagnostics have all led independently to better understanding of Rayleigh-Taylor (RT) instability, turbulence, and mixing. In particular, experiments have provided significant motivation for many simulation and modeling studies, as well as validation data. Numerical simulations, in turn, have also provided data not currently measurable or very difficult to measure accurately in RT unstable flows. Thus, simulations have motivated new measurements in this class of buoyancy-driven flows. This overview discusses simulation and modeling studies synergistic with experiments and examples of how experiments have motivated simulations and models of RT instability, flow, and mixing. First, a brief summary of measured experimental and calculated simulation quantities, of experimental approaches, and of issues and challenges in the simulation and modeling of RT experiments is presented. Implicit large-eddy, direct numerical, and large-eddy simulations validated using RT experimental data are then discussed. This is followed by a discussion of modeling using analytical, modal, buoyancy-drag, and turbulent transport models of RT mixing experiments. The discussion will focus on three-dimensional RT mixing arising from multimode perturbations. Finally, this review concludes with a perspective on future simulation, modeling, and experimental directions for further research. Research in simulation and modeling of RT unstable flows, coupled with experiments, has made significant progress over the past several decades. This overview serves as an opportunity to both discuss progress and to stimulate future research on simulation and modeling of this class of hydrodynamically-unstable turbulent flows.

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

“…In addition, these studies have allowed broadly to validate and verify turbulence mix-models [24][25][26][27][28][29][30][31][32] for buoyancydriven flows and provide insights to solve several long-standing problems in the field. The developments in modeling and simulations in RTI can be found in a companion review by Schilling [33], a review of the theoretical modeling techniques and issues related to variable-density flows with large thermal and density fluctuations can be found in [34]. No attempt is also made to cover the experiments related to the formation of RTI in the highenergy-density regime or RTI due to change in viscosity or chemical reactions; the reader can find those in other recent reviews [35,36].…”

Exploring the Atwood-number dependence of the highly nonlinear Rayleigh-Taylor instability regime in high-energy-density conditions

“…The MZ width evolution, however, is not solely due to RTI growth. Material expansion should also be taken into account and may represent a large fraction of the MZ [14]. In contrary, pure, non-HED, RTI develops in the absence of shock waves so there is no interaction with a shock or expansion to consider.…”

“…Despite its apparent simplicity, RTI remains nowadays an active field of study as testified by the recent reviews [12][13][14]. This is partially due to the complexity of all non-linear systems in fluid dynamics.…”

Incompressible Rayleigh-Taylor mixing in circular and spherical geometries

“…Rayleigh-Taylor (RT) instability and mixing, produced by the relative acceleration of two fluids of different densities, is of great importance in many natural and industrial processes. RT turbulent mixing occurs in disciplines as diverse as astrophysics [1,2], atmospheric physics [3], inertial confinement fusion [4], and laser-matter interactions [5,6] (see also [7][8][9][10][11] for recent reviews).…”