Connecting boundary layer dynamics with extreme bulk dissipation events in Rayleigh-B\'{e}nard flow

TL;DR

This study links boundary layer shear stress patterns to extreme energy dissipation events in Rayleigh-Bénard convection, revealing that plume detachment points can predict high dissipation events through boundary layer dynamics analysis.

Contribution

It introduces a novel connection between boundary shear stress patterns and bulk dissipation events, highlighting the role of plume detachment points as precursors in Rayleigh-Bénard flow.

Findings

Boundary shear stress zero points correlate with extreme dissipation events.

Proximity of detachment points at opposite plates predicts high dissipation events.

Transition from Gaussian to intermittent statistics indicates boundary layer breakdown.

Abstract

We study the connection between extreme events of thermal and kinetic energy dissipation rates in the bulk of three-dimensional Rayleigh-B\'{e}nard convection and the wall shear stress patterns at the top and the bottom planes that enclose the layer. Zero points of this two-dimensional vector field stand for detachments of strong thermal plumes. If their position at the opposite planes and a given time is close then they can be considered as precursors for high-amplitude bulk dissipation events triggered by plume collisions or close passings. This scenario requires a breaking of the synchronicity of the boundary layer dynamics at both plates which is found to be in line with a transition of the bulk derivative statistics from Gaussian to intermittent. Our studies are based on three-dimensional high-resolution direct numerical simulations for moderate Rayleigh numbers between $Ra=10^4$ and $5\times 10^5$.