Magnetic field generation by intermittent convection

TL;DR

This study investigates how intermittent convection in electrically conducting fluids influences magnetic field generation, identifying key regimes and mechanisms that facilitate dynamo action through numerical simulations.

Contribution

It provides new insights into the role of intermittency in magnetic field generation and determines the critical magnetic Prandtl number across different convective regimes.

Findings

Intermittent regimes significantly affect dynamo onset.

Critical magnetic Prandtl number varies with Rayleigh number.

Identifies convective regimes most conducive to dynamo action.

Abstract

Magnetic field generation in three-dimensional Rayleigh-B\'enard convection of an electrically conducting fluid is studied numerically by fixing the Prandtl number at $P=0.3$ and varying the Rayleigh number (Ra) as a control parameter. A recently reported route to hyperchaos involving quasiperiodic regimes, crises and chaotic intermittent attractors is followed, and the critical magnetic Prandtl number ($P_m^c$) for dynamo action is determined as a function of Ra. A mechanism for the onset of intermittency in the magnetic energy is described, the most beneficial convective regimes for dynamo action in this transition to weak turbulence are identified, and the impact of intermittency on the dependence of $P_m^c$ on Ra is discussed.