Chaotic magnetic field reversals in turbulent dynamos

TL;DR

This paper uses numerical simulations to study how magnetic field reversals occur in turbulent dynamos, highlighting the role of mode coupling and the magnetic Prandtl number in the process.

Contribution

It demonstrates that asymmetric forcing couples magnetic modes to induce reversals, with the mechanism's effectiveness depending on the magnetic Prandtl number.

Findings

Reversals are triggered by coupling dipolar and quadrupolar modes.

The reversal mechanism depends critically on the magnetic Prandtl number.

Simulations agree with recent theoretical models.

Abstract

We present direct numerical simulations of reversals of the magnetic field generated by swirling flows in a spherical domain. In agreement with a recent model, we observe that coupling dipolar and quadrupolar magnetic modes by an asymmetric forcing of the flow generates field reversals. In addition, we show that this mechanism strongly depends on the value of the magnetic Prandtl number.