Abstract
In this paper the stability of the non-uniformly rotating cylindrical plasma in the axial uniform magnetic field with the vertical temperature gradient is investigated. In the approximation of geometrical optics a dispersion equation for small axisymmetric perturbations is obtained with the effects of viscosity, ohmic and heat conductive dissipation taken into account. The stability criteria for azimuthal plasma flows are obtained in the presence of the vertical temperature gradient and the constant magnetic field. The Rayleigh-Benard problem for stationary convection in the non-uniformly rotating layer of the electrically conducting fluid in the axial uniform magnetic field is considered. In the linear theory of stationary convection the critical value of the Rayleigh number subject to the profile of the inhomogeneous rotation (Rossby number) is obtained. It is shown that the negative values of the Rossby number have a destabilizing effect, since the critical Rayleigh number becomes smaller, than in the case of the uniform rotation , or of the rotation with positive Rossby numbers . To describe the nonlinear convective phenomena the local Cartesian coordinate system was used, where the inhomogeneous rotation of the fluid layer was represented as the rotation with a constant angular velocity and azimuthal shear with linear dependence on the coordinate. As a result of applying the method of perturbation theory for the small parameter of supercriticality of the stationary Rayleigh number a nonlinear Ginzburg-Landau equation was obtaned. This equation describes the evolution of the finite amplitude of perturbations by utilizing the solution of the Ginzburg-Landau equation. It is shown that the weakly nonlinear convection based on the equations of the six-mode Lorentz model transforms into the identical Ginzburg-Landau equation. By utilizing the solution of the Ginzburg-Landau equation, we determined the dynamics of unsteady heat transfer for various profiles of the angular velocity of the rotation of electrically conductive fluid.
Highlights
In this paper the stability of the non-uniformly rotating cylindrical plasma in the axial uniform magnetic field with the vertical temperature gradient is investigated
It is shown that the weakly nonlinear convection based on the equations of the six-mode (6D) Lorentz model transforms into the identical Ginzburg-Landau equation
The temperature of the lower part of the layer is denoted by Td, and the upper one – by Tu, while Td > Tu is the heating from the bottom (Fig. 3)
Summary
The Rayleigh-Benard problem for stationary convection in the non-uniformly rotating layer of the electrically conducting fluid in the axial uniform magnetic field is considered. Unlike the Childress-Soward and Busse models, the stability of a non-uniformly rotating layer of the electrically conducting fluid in the axial magnetic field, in which the lower surface of the layer (Td ) is hotter than the upper one (Tu ) (Rayleigh-Benard problem): Td > Tu , was studied in [36] (Fig. 2b). The aim of this work is to study local instabilities in rotating flows in the presence of a constant vertical magnetic field and the temperature gradient in the field of gravity, as well as the development of a linear and weakly nonlinear theory of the stationary convection in a non-uniformly rotating layer of the electrically conductive fluid in the axial uniform magnetic field. Substituting decompositions (8) into the system of equations (6), we obtain the system of local differential equations for ε −1 and ε 0 orders: DΦ
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