Numerical investigation of initial condition effects on Rayleigh-Taylor instability with acceleration reversals

Abstract

The influence of initial conditions on miscible incompressible baroclinically driven Rayleigh-Taylor instability undergoing non-uniform acceleration is explored computationally using an Implicit Large Eddy Simulation (ILES) technique. We consider the particular case of evolution during multiple reversals of acceleration direction, where the flow is alternately statically stable or unstable. In the unstable phase, the flow is driven by the baroclinic release of potential energy, whereas in the stable phase, work is done against the density stratification with the energy exchange taking place by wave-like mechanisms. These dynamics are fundamentally different; here, we track the evolution of volume-averaged turbulent statistics that are most sensitive to changes in the distribution of spectral power and bandwidth of the initial conditions as the flow alternates between dynamical regimes due to acceleration reversal.3

Knudsen Number Effects on Two-Dimensional Rayleigh–Taylor Instability in Compressible Fluid: Based on a Discrete Boltzmann Method

“…In the same year, Zhou et al used a numerical method to analyze the statistics of the kinetic energy and thermal energy dissipation rate of 2D RT turbulence [ 28 ]. Aslangil et al used an implicit large eddy simulation technique to analyze the effect of initial conditions on the stability of miscible incompressible barotropic pressure driven RT under non-uniform acceleration conditions [ 29 ]. In 2018, Zhang et al studied the instability of 2D and 3D multimode ablation RT.…”

Rayleigh–Taylor Instability With Varying Periods of Zero Acceleration

“…As a result, increasing attention has been given in recent years to Rayleigh-Taylor instability undergoing variable acceleration (see, in particular, Refs. [15][16][17][18][19][20][21][22]).…”

“…Subsequent work compared implicit large eddy simulations (ILES) [23] with previously unpublished experimental results (A ¼ 0.48) [24], and it was concluded that ILES with a broadband initial perturbation spectrum matched the experiments. Some more recent work has focused on the sensitivity of future development to initial conditions [19] and has found that structural features of the initial condition persist through to the second acceleration. Another recent study also examined the sensitivity to duration of deceleration [21].…”

“…The behavior of RTI undergoing ADA tends to be dominated by peripheral structures, particularly during the deceleration phase [19]. Here, there is no further growth of the mixing layer, yet the layer continues to mix, collapsing the distribution of densities within the layer.…”

Experiments and Simulations on the Turbulent, Rarefaction Wave Driven Rayleigh–Taylor Instability

“…Later, one of the most important numerical simulations conducted was the 3072 3 direct numerical simulation of multimode RTI by Cabot and Cook [22]. More recently, the numerical investigations of Aslangil et al [23] and Ramaprabhu et al [24] have focused on the effects of time varying acceleration profiles. Turbulent RTI has been described as a process of self-similar mixing layer growth resulting from the interaction of bubbles of different length scales.…”