Bistability and chaos in Taylor-Green dynamo

TL;DR

This study uses direct numerical simulations to explore various dynamo states, including bistability and chaos, under Taylor-Green forcing with low Prandtl number, revealing complex transitions and routes to chaos.

Contribution

It demonstrates the existence of bistability, multiple dynamo states, and routes to chaos in Taylor-Green dynamo simulations at low Prandtl numbers, highlighting complex dynamical behavior.

Findings

Bistability with weak and strong magnetic field branches.

Multiple dynamo states including constant, periodic, quasiperiodic, and chaotic.

Identification of routes to chaos such as quasiperiodic route with phase locking and Newhouse-Ruelle-Takens route.

Abstract

Using direct numerical simulations we study dynamo action under the Taylor-Green forcing with Prandtl number less than one. We observe bistability with a weak magnetic field branch and a strong magnetic field branch. Both the dynamo branches undergo subcritical dynamo transition. We also observe host of dynamo states including constant, periodic, quasiperiodic, and chaotic magnetic fields. One of the chaotic state originates through a quasiperiodic route with phase locking, while another chaotic attractor appears to follow Newhouse-Ruelle-Takens route to chaos. We also observe intermittent transitions among quasiperiodic and chaotic states for a given Taylor-Green forcing.