scholarly journals On the Kelvin-Helmholtz Discontinuity in Two Superposed Plasmas

1974 ◽  
Vol 27 (1) ◽  
pp. 53 ◽  
Author(s):  
Prem Kumar Bhatia ◽  
Joseph Mendel Steiner
Keyword(s):  
Magnetic Field ◽  
Collision Frequency ◽  
Plane Interface ◽  
Ambient Magnetic Field ◽  
Neutral Particles ◽  
Stabilizing Effect ◽  
The Stability

An investigation has been made of the effects of collisions with neutral particles on the stability of the plane interface separating two streaming superposed plasmas of uniform densities. It has been found that, whereas the ambient magnetic field has a stabilizing influence, a collision frequency has a stabilizing effect when it is small and a destabilizing effect when it exceeds a certain value.

HYDROMAGNETIC KELVIN INSTABILITY IN THE PRESENCE OF NEUTRAL PARTICLES

1967 ◽  
Vol 45 (8) ◽  
pp. 2779-2785 ◽  
Author(s):  
S. S. Rao ◽  
G. L. Kalra
Keyword(s):  
Magnetic Field ◽  
Speed Of Sound ◽  
Uniform Magnetic Field ◽  
Collision Frequency ◽  
Wave Number ◽  
Tangential Discontinuity ◽  
Neutral Particles ◽  
The Stability

The stability of a tangential discontinuity in velocity in a plasma mixed with cold neutral particles is investigated in the presence of a uniform magnetic field. It is found that the effect of collisions between the plasma and the neutral particles is stabilizing or destabilizing according as ν, the collision frequency, is less than or greater than the parameter kc, where k is the wave number of the perturbation and c is the speed of sound for the plasma.

Resistive instability in a uniformly rotating magnetoplasma

1971 ◽  
Vol 6 (1) ◽  
pp. 73-85
Author(s):  
A. D. Lunn
Keyword(s):  
Magnetic Field ◽  
Growth Rates ◽  
Larmor Radius ◽  
Closed Set ◽  
Finite Larmor Radius ◽  
Integral Methods ◽  
Stabilizing Effect ◽  
Instability Growth ◽  
Linear Differential ◽  
The Stability

A closed set of guiding centre equations, derived for a rotating plasma in a static magnetic field, is applied to the problem of the stability of a plasma in a sheared field. The rotation is found to have a stabilizing effect in the absence of resistivity.A pair of coupled, linear differential equations is derived for the rotating plasma in a weakly sheared field. Dispersion relations are obtained by phase integral methods and, in the absence of finite Larmor radius effects and rotation, instability growth rates proportional to η½13 are found which become proportional to when either is included. The inclusion of both finite Larmor radius and rotation gives growing instabilities proportional to η which are stabilized by the rotation when the finite Larmor radius terms predominate.

On the Hydromagnetic Kelvin-Helmholtz Instability between Compressible Fluids

1974 ◽  
Vol 29 (6) ◽  
pp. 888-892 ◽  
Author(s):  
K. M. Srivastava
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Compressible Fluids ◽  
Plane Interface ◽  
Helmholtz Instability ◽  
Solar Plasma ◽  
The Stability ◽  
Conducting Fluids ◽  
Equal Density

We have discussed the effect of gravity on the hydromagnetic Kelvin-Helmholtz instability of a plane interface between compressible, inviscid, infinitely conducting fluids. The stability of the interface is investigated including gravity. The solar plasma and the magnetospheric medium are supposed to be of equal density and to carry a uniform magnetic field (H ) in the direction of streaming. The cases (i) H1 ≠ H2 and x1 (x = cp/cv) not necessarily equal to x2 , (ii) H1= H2 x1 ≠ x2 and (iii) H1 = H2, x1=x2 are discussed for perturbations, transverse as well as parallel to the direction of streaming. It is concluded that the interface is unstable in all the cases except for transverse perturbations, the two media carrying the same magnetic field and being characterized by the same x, when it is found to be verlocity.

scholarly journals The effect of compressibility, rotation and magnetic field on thermal instability of Walters’ fluid permeated with suspended particles in porous medium

2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 539-550 ◽  
Author(s):  
Kumar Aggarwal ◽  
Anushri Verma
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Normal Mode Analysis ◽  
Suspended Particles ◽  
Elastic Parameter ◽  
Mode Analysis ◽  
Medium Permeability ◽  
Stabilizing Effect ◽  
Model Fluid ◽  
The Stability

The purpose of this paper is to study the effects of compressibility, rotation, magnetic field and suspended particles on thermal stability of a layer of visco-elastic Walters? (model) fluid in porous medium. Using linearized theory and normal mode analysis, dispersion relation has been obtained. In case of stationary convection, it is found that the rotation has stabilizing effect on the system. The magnetic field may have destabilizing effect on the system in the presence of rotation while in the absence of rotation it always has stabilizing effect. The medium permeability has destabilizing effect on the system in the absence of rotation while in the presence of rotation it may have stabilizing effect. The suspended particles and compressibility always have destabilizing effect. Due to vanishing of visco-elastic parameter, the compressible visco-elastic fluid behaves like Newtonian fluid. Graphs have also been plotted to depict the stability characteristics. The viscoelasticity, magnetic field and rotation are found to introduce oscillatory modes into the system which were non-existent in their absence.

Hydromagnetic Instability Criteria for Stratified Viscoelastic Dusty Finitely Conducting Plasmas

2004 ◽  
Vol 59 (12) ◽  
pp. 893-911
Author(s):  
M. F. El-Sayed
Keyword(s):  
Magnetic Field ◽  
Kinematic Viscosity ◽  
Mass Concentration ◽  
Viscoelastic Model ◽  
Suspended Particles ◽  
Relaxation Frequency ◽  
Hydromagnetic Instability ◽  
Stabilizing Effect ◽  
The Stability ◽  
Alfven Velocity

The instability of a stratified, viscoelastic (Walters B’ or Rivlin-Ericksen) magnetoplasma, including the effects of finite resistivity and suspended particles, is investigated using linear analysis. The horizontal applied magnetic field and the viscosity, as well as the viscoelasticity of the medium are assumed to be variable. The dispersion relation, which is obtained for the general case on employing boundary conditions appropriate to the case of two free boundaries, is then specialized for the two models. The hydromagnetic instability conditions are obtained and discussed analytically, and the results are numerically confirmed. The variation of the growth rate of the unstable modes with the different parameters has been evaluated analytically. All the physical parameters are found to have stabilizing as well as destabilizing effects on the considered system. For the Walters B’ viscoelastic model it was found that the kinematic viscoelasticity, fluid resistivity, and stratification parameter have a stabilizing effect, while the mass concentration (or relaxation frequency) of the suspended particles, kinematic viscosity, and Alfvén velocity have a destabilizing effect on the considered system. Also, for the case of the Rivlin-Ericksen viscoelastic model we found that the mass concentration of the suspended particles, Alfvén velocity, and kinematic viscosity have a stabilizing effect, while both the finite resistivity and stratification parameter have a destabilizing effect; the relaxation frequency of the suspended particles has no effect on the stability of the system. The case of a dusty plasma with infinite conductivity and presence (or absence) of a magnetic field is also considered. Its stability conditions are obtained, from which it is concluded that the presence of dust always reduces the growth rate of the unstable Rayleigh-Taylor perturbations. The limiting case of a viscid (and inviscid) finitely conducting dusty plasma is considered, and the stability conditions are discussed, from which we found that the magnetic field has a stabilizing effect in the absence of both viscosity and finite resistivity, the stability of the system ocurrs for values of the Alfvén velocity greater than a critical value. -PACS: 47.20.-k; 47.50+d; 47.65.+a.

EFFECT OF FINITE ION LARMOR RADIUS ON THE STABILITY OF SUPERPOSED FLUIDS

1967 ◽  
Vol 45 (4) ◽  
pp. 1579-1585 ◽  
Author(s):  
G. L. Kalra
Keyword(s):  
Magnetic Field ◽  
Vortex Sheet ◽  
Larmor Radius ◽  
General Direction ◽  
Ambient Magnetic Field ◽  
The Stability ◽  
Superposed Fluids

The effect of finite ion Larmor radius on the problem of stability of incompressible and infinitely conducting superposed fluids is investigated for a general direction of perturbation. It is found that whereas the interchange perturbations are stabilized in the presence of Larmor radius, the noninterchange perturbations (which affect the ambient magnetic field) lead to overstability due to Larmor radius effects in a configuration (unstable in the absence of magnetic field) stabilized by a strong enough magnetic field. The configuration which is monotonically unstable in the absence of Larmor radius now, in addition, exhibits overstable modes. Similar conclusions are obtained in the presence of vortex sheet as well.

scholarly journals Magnetohydrodynamic Stability of Streaming Jet Pervaded Internally by Varying Transverse Magnetic Field

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Alfaisal A. Hasan
Keyword(s):  
Magnetic Field ◽  
Numerical Analysis ◽  
Transverse Magnetic Field ◽  
Capillary Force ◽  
Present Model ◽  
Transverse Magnetic ◽  
Exterior Field ◽  
Stabilizing Effect ◽  
Basic Equations ◽  
The Stability

The Magnetohydrodynamic stability of a streaming cylindrical model penetrated by varying transverse magnetic field has been discussed. The problem is formulated, the basic equations are solved, upon appropriate boundary conditions the eigenvalue relation is derived and discussed analytically, and the results are verified numerically. The capillary force is destabilizing in a small axisymmetric domain and stabilizing otherwise. The streaming has a strong destabilizing effect in all kinds of perturbation. The toroidal varying magnetic field interior the fluid has no direct effect at all on the stability of the fluid column. The axial exterior field has strong stabilizing effect on the model. The effect of all acting forces altogether could be identified via the numerical analysis of the stability theory of the present model.

scholarly journals Thermal convection of dusty compressible Rivlin-Ericksen viscoelastic fluid with hall currents

2012 ◽  
Vol 16 (1) ◽  
pp. 177-192 ◽  
Author(s):  
Urvashi Gupta ◽  
Parul Aggarwal ◽  
Kumar Wanchoo
Keyword(s):  
Magnetic Field ◽  
Thermal Instability ◽  
Normal Modes ◽  
Suspended Particles ◽  
Stationary Convection ◽  
Viscoelastic Parameter ◽  
Electrically Conducting ◽  
Stabilizing Effect ◽  
The Stability ◽  
Rayleigh Numbers

An investigation is made on the effect of Hall currents and suspended particles on the hydromagnetic stability of a compressible, electrically conducting Rivlin-Ericksen elastico-viscous fluid. The perturbation equations are analyzed in terms of normal modes after linearizing the relevant set of hydromagnetic equations. A dispersion relation governing the effects of viscoelasticity, magnetic field, Hall currents, compressibility and suspended particles is derived. For the stationary convection Rivlin-Ericksen fluid behaves like an ordinary Newtonian fluid due to the vanishing of the viscoelastic parameter. Compressibility and magnetic field are found to have a stabilizing effect on the system whereas Hall currents and suspended particles hasten the onset of thermal instability. These analytic results are confirmed numerically and the effects of various parameters on the stability parameter are depicted graphically. The critical Rayleigh numbers and the wavenumbers of the associated disturbances for the onset of instability as stationary convection are obtained and the behavior of various parameters on critical thermal Rayleigh numbers has been depicted graphically. It has been observed that oscillatory modes are introduced due to the presence of viscoelasticity, suspended particles and Hall currents which were not existing in the absence of these parameters.

scholarly journals Effect of magnetic field on thermal instability of a rotating Rivlin-Ericksen viscoelastic fluid

2006 ◽  
Vol 2006 ◽  
pp. 1-10
Author(s):  
Pardeep Kumar ◽  
Hari Mohan ◽  
Roshan Lal
Keyword(s):  
Magnetic Field ◽  
Newtonian Fluid ◽  
Viscoelastic Fluid ◽  
Thermal Instability ◽  
Vertical Magnetic Field ◽  
Stationary Convection ◽  
Stabilizing Effect ◽  
The Stability ◽  
The Magnetic Field

The thermal instability of a rotating Rivlin-Ericksen viscoelastic fluid in the presence of uniform vertical magnetic field is considered. For the case of stationary convection, Rivlin-Ericksen viscoelastic fluid behaves like a Newtonian fluid. It is found that rotation has a stabilizing effect, whereas the magnetic field has both stabilizing and destabilizing effects. Graphs have been plotted by giving numerical values to the parameters, to depict the stability characteristics. The rotation and magnetic field are found to introduce oscillatory modes in the system which were nonexistent in their absence.

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