Stability of rotating stratified fluid in the presence of a variable horizontal magnetic field

1977 ◽  
Vol 43 (2) ◽  
pp. 157-162
Author(s):  
R. C. Sharma
Keyword(s):  
Magnetic Field ◽  
Stratified Fluid ◽  
Horizontal Magnetic Field ◽  
Rotating Stratified Fluid

Hydromagnetic wavelike instabilities in a rapidly rotating stratified fluid

1973 ◽  
Vol 61 (3) ◽  
pp. 609-624 ◽  
Author(s):  
D. J. Acheson
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Growth Rates ◽  
Homogeneous Model ◽  
Stratified Fluid ◽  
Generation Mechanism ◽  
Helmholtz Instability ◽  
Coaxial Cylinders ◽  
The Magnetic Field ◽  
Rotating Stratified Fluid

We examine the hydromagnetic stability of a radially stratified fluid rotating between two coaxial cylinders, with particular emphasis on the case when the angular velocity greatly exceeds both buoyant and Alfvén frequencies. If the magnetic field is predominantly azimuthal instabilities then have an essentially non-axisymmetric and wavelike character. Various bounds on their phase speeds and growth rates are derived, including a ‘quadrant’ theorem analogous to Howard's semicircle theorem for Kelvin–Helmholtz instability. Their strong tendency to propagate against the basic rotation (i.e. ‘westward’), previously noted by the author in the study of a more simplified (homogeneous) model, seems relatively insensitive to the generation mechanism (e.g. unstable gradient of magnetic field, angular velocity or density), but a number of counterexamples show that this constraint need not apply if the magnetic field displays significant spatial variations of direction as well as magnitude and that eastward-propagating amplifying modes are then possible.

Stability of aligned magnetoatmospheric flow

1978 ◽  
Vol 19 (1) ◽  
pp. 77-86 ◽  
Author(s):  
J. A. Adam
Keyword(s):  
Magnetic Field ◽  
Shear Flow ◽  
Atmospheric Model ◽  
Stratified Fluid ◽  
Sufficient Condition ◽  
Stationary Equilibrium ◽  
Horizontal Magnetic Field ◽  
Energy Principle ◽  
Simple Generalization ◽  
The Stability

Using the stationary equilibrium energy principle a sufficient condition is obtained for the stability of a compressible stratified fluid with a non-uniform horizontal magnetic field, with an aligned shear flow. The condition is used to provide a simple generalization of a known result for a specific atmospheric model.

Two-dimensional oscillation of convection roll in a finite liquid metal layer under a horizontal magnetic field

2021 ◽  
Vol 911 ◽  
Author(s):  
Y. Tasaka ◽  
T. Yanagisawa ◽  
K. Fujita ◽  
T. Miyagoshi ◽  
A. Sakuraba
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Metal Layer ◽  
Two Dimensional ◽  
Horizontal Magnetic Field ◽  
Convection Roll

Abstract

The Magnetic Anisotropy of Stretched Rubber as a Function of the Tension to Which It Is Subjected

1945 ◽  
Vol 18 (1) ◽  
pp. 8-9 ◽  
Author(s):  
Eugénie Cotton-Feytis
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Uniaxial Crystal ◽  
Horizontal Magnetic Field ◽  
First Approximation ◽  
The Difference ◽  
The Times ◽  
Angular Displacements ◽  
The Magnetic Field ◽  
Oscillation Method

Abstract From the standpoint of its magnetic anisotropy, stretched rubber is comparable in a first approximation to a uniaxial crystal, in which the direction of the axis is the same as the direction of elongation. It is possible to measure this anisotropy by means of the oscillation method used by Krishnan, Guha and Banerjee in studying crystals. The sample to be examined is suspended in a uniform horizontal magnetic field in such a manner that its axis is horizontal. It is then so arranged that the torsion of the suspension wire is zero when the rubber sample is in a position of equilibrium in the field. The times of oscillation T′ and T for very small angular displacements around this position, in the presence and then in the absence of the magnetic field, are then recorded. In this way the difference between the specific susceptibilities in the direction of the axis and in the horizontal direction perpendicular to the axis is calculated by application of the equation:

Numerical Solution of Melting Processes for Fixed and Unfixed Phase Change Material in the Presence of Magnetic Field: Simulation of Low Gravity Environment

2001 ◽  
Author(s):  
Y. Asako ◽  
E. Gonçalves ◽  
M. Faghri ◽  
M. Charmchi
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Phase Change ◽  
Phase Change Material ◽  
Flow Patterns ◽  
Transport Processes ◽  
Low Gravity ◽  
Horizontal Magnetic Field ◽  
Wall Heating ◽  
Change Material

Abstract Transport processes associated with melting of an electrically conducting Phase Change Material (PCM), placed inside a rectangular enclosure, under low-gravity environment, and in the presence of a magnetic field is simulated numerically. Electromagnetic forces damp the natural convection as well as the flow induced by sedimentation and/or floatation, and thereby simulating the low gravity environment of outer space. Computational experiments are conducted for both side-wall heating and top-wall heating under horizontal magnetic field. The governing equations are discretized using a control-volume-based finite difference scheme. Numerical solutions are obtained for true low-gravity environment as well as for the simulated-low-gravity conditions resulted by the presence of a horizontal magnetic field. The effects of magnetic field on the natural convection, solid phase floatation/sedimentation, liquid-solid interface location, solid melting rate, and flow patterns are investigated. It is found that the melting under low-gravity environment can reasonably be simulated on earth via applying a strong horizontal magnetic field. However, the flow patterns obtained for the true low-gravity cases are not similar to the corresponding cases solved for the simulated-low-gravity environment.

scholarly journals Time scale of the largest imaginable magnetic storm

2013 ◽  
Vol 20 (1) ◽  
pp. 19-23 ◽  
Author(s):  
V. M. Vasyliūnas
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Storm ◽  
Energy Content ◽  
Horizontal Magnetic Field ◽  
Order Of Magnitude ◽  
Magnetosphere Plasma ◽  
Time Required ◽  
Parameter Values ◽  
Magnetic Field Perturbation

Abstract. The depression of the horizontal magnetic field at Earth's equator for the largest imaginable magnetic storm has been estimated (Vasyliūnas, 2011a) as −Dst ~ 2500 nT, from the assumption that the total pressure in the magnetosphere (plasma plus magnetic field perturbation) is limited, in order of magnitude, by the minimum pressure of Earth's dipole field at the location of each flux tube. The obvious related question is how long it would take the solar wind to supply the energy content of this largest storm. The maximum rate of energy input from the solar wind to the magnetosphere can be evaluated on the basis either of magnetotail stress balance or of polar cap potential saturation, giving an estimate of the time required to build up the largest storm, which (for solar-wind and magnetospheric parameter values typical of observed superstorms) is roughly between ~2 and ~6 h.

Sign in / Sign up

Export Citation Format

Share Document