Fluctuation dynamo amplified by intermittent shear bursts in convectively driven magnetohydrodynamic turbulence

TL;DR

This paper investigates how intermittent shear bursts in convectively driven MHD turbulence can significantly amplify magnetic energy through dynamo action, highlighting their importance in sustaining magnetic fields.

Contribution

It reveals that spontaneous, large-scale shear bursts are frequent and play a crucial role in magnetic energy amplification in turbulent MHD convection.

Findings

Shear bursts occur frequently and spontaneously in simulations.

Shear bursts lead to elevated magnetic energy growth.

Magnetic energy amplification persists over long time scales.

Abstract

Intermittent large-scale high-shear flows are found to occur frequently and spontaneously in direct numerical simulations of statistically stationary turbulent Boussinesq magnetohydrodynamic (MHD) convection. The energetic steady-state of the system is sustained by convective driving of the velocity field and small-scale dynamo action. The intermittent emergence of flow structures with strong velocity and magnetic shearing generates magnetic energy at an elevated rate over time-scales longer than the characteristic time of the large-scale convective motion. The resilience of magnetic energy amplification suggests that intermittent shear-bursts are a significant driver of dynamo action in turbulent magnetoconvection.