Parametric investigation of the transition to turbulence in Rayleigh-Taylor mixing

A database is developed consisting of highly resolved large-eddy simulations of the transition process in a Rayleigh-Taylor mixing layer. Over 300 simulations are performed with parametric variations in Grash of number, Schmidt number, At wood number, and initial perturbation spectrum. The database is then analyzed to explore how the factors that influence the transition-to-turbulence process impact mixing evolution and growth rate prior to the development of late-time, steady-state growth. The competition between entrainment-driven mixing and diffusion-driven mixing is observed, and two different mechanisms are suggested by which the homogeneity of mixing might increase, rather than decrease, at early time. The impact of parametric variation on growth rate is additionally examined, and all variations in initial conditions are found to converge to approximately the same growth parameter around alpha approximate to 0.025. (C) 2019 Elsevier B.V. All rights reserved.