Generation of magnetic fields by thermomagnetic effects in a nonuniformly rotating layer of an electrically conductive fluid

TL;DR

This paper investigates how thermomagnetic effects generate magnetic fields in a nonuniformly rotating electrically conductive fluid layer, analyzing their impact on convective instability and heat transfer through nonlinear Ginzburg-Landau equations.

Contribution

It introduces a nonlinear Ginzburg-Landau model for magnetic field generation due to thermomagnetic effects in rotating fluids, highlighting the influence on magnetic field amplitude and heat transfer.

Findings

Thermomagnetic effects significantly increase stationary toroidal magnetic field amplitude.

The derived Ginzburg-Landau equation describes perturbation evolution in the fluid.

Numerical solutions show altered heat transfer with thermomagnetic effects.

Abstract

In this paper, the generation of magnetic fields in a nonuniformly rotating layer of finite thickness of an electrically conducting fluid by thermomagnetic (TM) instability. This instability arises due to the temperature gradient $\nabla T_0$ and thermoelectromotive coefficient gradient $\nabla\alpha $. The influence of the generation of a toroidal magnetic field by TM instability on convective instability in a nonuniformly rotating layer of an electrically conductive fluid in the presence of a vertical constant magnetic field ${\bf{B}}_0 \| {\rm OZ}$ is established. As a result of applying the method of perturbation theory for the small parameter $ \epsilon = \sqrt {(\textrm {Ra}-\textrm {Ra}_c) / \textrm {Ra}_c} $ of supercriticality of the stationary Rayleigh number $\textrm {Ra}_c$ a nonlinear equation of the Ginzburg-Landau type was obtained. This equation describes the evolution of the finite amplitude of perturbations. Numerical solutions of this equation made it possible to determine the heat transfer in the fluid layer with and without TM effects. It is shown that the amplitude of the stationary toroidal magnetic field noticeably increases with allowance for TM effects.