Non-Gaussian buoyancy statistics in fingering convection

TL;DR

This paper investigates the non-Gaussian statistics of buoyancy fluctuations in high-Rayleigh number fingering convection through high-resolution simulations and a modified theoretical model emphasizing the role of coherent structures.

Contribution

It introduces a novel application of Yakhot's approach to model active scalar distributions in fingering convection, highlighting the influence of coherent structures.

Findings

Buoyancy fluctuations exhibit significantly non-Gaussian tails.

Coherent structures play a key role in scalar statistics.

The modified theory successfully models the scalar distribution.

Abstract

We examine the statistics of active scalar fluctuations in high-Rayleigh number fingering convection with high-resolution three-dimensional numerical experiments. The one-point distribution of buoyancy fluctuations is found to present significantly non-Gaussian tails. A modified theory based on an original approach by Yakhot (1989) is used to model the active scalar distributions as a function of the conditional expectation values of scalar dissipation and fluxes in the flow. Simple models for these two quantities highlight the role of blob-like coherent structures for scalar statistics in fingering convection.