On instability of the magnetic Bénard problem with Hall and ion-slip effects

2004 ◽  
Vol 42 (10) ◽  
pp. 1001-1012 ◽  
Author(s):  
L. Palese ◽  
A. Georgescu
Keyword(s):  
Slip Effects ◽  
Bénard Problem ◽  
Ion Slip ◽  
Benard Problem

On the two-component Benard problem a numerical solution

1975 ◽  
Vol 80 (1) ◽  
pp. 76-88 ◽  
Author(s):  
J.C. Legros ◽  
D. Longree ◽  
G. Chavepeyer ◽  
J.K. Platten
Keyword(s):  
Numerical Solution ◽  
Two Component ◽  
Bénard Problem ◽  
Benard Problem

Stabilization of the no-motion state in the Rayleigh–Bénard problem

1994 ◽  
Vol 447 (1931) ◽  
pp. 587-607 ◽  
Keyword(s):  
Fluid Layer ◽  
Critical Rayleigh Number ◽  
Control Flow ◽  
Feedback Controller ◽  
Linear Stability Theory ◽  
Motion State ◽  
Conduction State ◽  
Bénard Problem ◽  
Benard Problem ◽  
Rayleigh Benard

Using linear stability theory and numerical simulations, we demonstrate that the critical Rayleigh number for bifurcation from the no-motion (conduction) state to the motion state in the Rayleigh–Bénard problem of an infinite fluid layer heated from below and cooled from above can be significantly increased through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid’s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary’s temperature or velocity are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behaviour at relatively low Rayleigh numbers.

scholarly journals Existence and Homogenization of the Rayleigh-Bénard Problem

2000 ◽  
Vol 7 (2) ◽  
pp. 136-169 ◽  
Author(s):  
Björn Birnir ◽  
Nils Svanstedt
Keyword(s):  
Bénard Problem ◽  
Benard Problem ◽  
Rayleigh Benard

The Effects of Hall and Ion Slip on the Electrical Conductivity of Partially Ionized Gases for Magnetohydrodynamic Re-Entry Vehicle Application

1962 ◽  
Vol 84 (2) ◽  
pp. 177-184 ◽  
Author(s):  
M. J. Brunner
Keyword(s):  
Electrical Conductivity ◽  
Cross Sections ◽  
Effective Conductivity ◽  
Ionized Gas ◽  
Equilibrium Conditions ◽  
Degree Of Ionization ◽  
Slip Effects ◽  
Wide Range ◽  
Ion Slip ◽  
Partially Ionized

The presence of a partially ionized gas around a hypersonic vehicle permits the application of magnetohydrodynamic (MHD) devices during re-entry. The operation of such MHD devices on a re-entry vehicle will largely depend on the magnitude of the electrical conductivity of the gas between the electrodes. In some cases it may be necessary to seed the air in order to insure high conductivity. The operation of the re-entry vehicle at relatively low gas densities and high magnetic fields will produce Hall and ion slip effects which may materially reduce the effective conductivity between the electrodes. The electrical conductivity including Hall and ion slip effects for air is presented for a wide range of pressures and temperatures and for a typical re-entry vehicle, with and without seeding. The electrical conductivity is evaluated for equilibrium conditions considering the number density and collision cross sections for electrons, neutrals, and ions. The Hall and ion slip effects are evaluated from the degree of ionization, the cyclotron frequency, and the time between collisions for electrons, neutrals, and ions.

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