Transitional model for rarefaction-driven Rayleigh−Taylor mixing on the diffuse interface

Abstract

Large eddy simulations are performed to explore transitional characteristics with parametric variations under initial conditions for rarefaction-driven Rayleigh–Taylor mixing flows and to develop a transitional model for the prediction of transition onset. Three-dimensional, multi-mode perturbations imposed on the diffuse interface are excited by a rarefaction wave, resulting in a large but non-constant acceleration. Initial conditions investigated here profoundly impact characteristic transition times through the variation in the net contributions between the advection and pressure components dominated in the laminar regimes, making the spatial transition criteria sensitive and questionable as well as the temporal transition criteria insensitive and feasible. Therefore, a new transition model originating from empirical correlations and ignoring physical details is calibrated and tested in a series of numerical realizations, and it is certified that the modeling framework is sufficiently flexible, accurate, and robust and can be a promising strategy for handling complex transitional phenomena.