Nonlinear dynamo in obliquely rotating stratified electroconductive fluid in an uniformly magnetic field

TL;DR

This paper investigates a new large-scale instability in obliquely rotating stratified electroconductive fluids under a uniform magnetic field, revealing nonlinear dynamo behavior and localized chaotic structures through analytical and numerical methods.

Contribution

It introduces a novel type of large-scale instability driven by small-scale oscillations in a stratified, rotating, electroconductive fluid with a magnetic field, using multi-scale asymptotic expansions.

Findings

Identified a new large-scale instability mechanism.

Derived nonlinear equations for vortex and magnetic perturbations.

Found stationary localized chaotic structures numerically.

Abstract

We study a new type of large-scale instability, which arises in obliquely rotating stratified electroconductive fluid with an external uniform magnetic field and a small-scale external force having zero helicity. This force gives rise to small-scale oscillations of the velocity with a small Reynolds number. Using the method of multi-scale asymptotic expansions there are obtained nonlinear equations for vortex and magnetic perturbations in the third order in Reynolds number. Studied is the linear stage of magneto-vortex dynamo caused by instabilities of $\alpha$-effect type. Stationary solutions for the equations of nonlinear magneto-vortex dynamo are found by numerical methods in the form of localized chaotic structures.