INSTABILITIES IN THE NON-UNIFORMLY ROTATING MEDIUM WITH TEMPERATURE STRATIFICATION IN THE EXTERNAL UNIFORM MAGNETIC FIELD

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 Ra-c subject to the profile of the inhomogeneous rotation (Rossby number Ro) is obtained. It is shown that the negative values of the Rossby number Ro < 0 have a destabilizing effect, since the critical Rayleigh number Ra-c becomes smaller, than in the case of the uniform rotation Ro = 0, or of the rotation with positive Rossby numbers Ro > 0. 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 (Omega) over right arrow (0). and azimuthal shear (U) over right arrow (0)(x). with linear dependence on the coordinate x. 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 (6D) 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.