Kolmogorov and Bolgiano scaling in thermal convection: the case of Rayleigh-Taylor turbulence

TL;DR

This paper studies Rayleigh-Taylor turbulence in a confined geometry, revealing how the system transitions between Kolmogorov and Bolgiano scaling regimes depending on the confinement scale and the evolution stage.

Contribution

It demonstrates the influence of confinement on Bolgiano scale and identifies a transition from three to two-dimensional turbulence regimes in Rayleigh-Taylor convection.

Findings

The Bolgiano scale is set by the system's confinement.

At late stages, turbulence exhibits Kolmogorov at small scales and Bolgiano at large scales.

A transition from three to two-dimensional turbulence occurs when the mixing layer exceeds the confinement scale.

Abstract

We investigate the statistical properties of Rayleigh-Taylor turbulence in a convective cell of high aspect ratio, in which one transverse side is much smaller that the others. We show that the scale of confinement determines the Bolgiano scale of the system, which in the late stage of the evolution is characterized by the Kolmogorov-Obukhov and the Bolgiano-Obukhov phenomenology at small and large scales, respectively. The coexistence of these regimes is associated to a three to two-dimensional transition of the system which occurs when the width of the turbulent mixing layer becomes larger that the scale of confinement.