Asymptotic and Numerical Analysis of the Magnetic Field Generation Process in the Couette-Poiseuille Flow of an Electrically Conducting Fluid

2013 ◽  
pp. 43-50
Author(s):  
E. M. Graeva ◽  
A. A. Soloviev
Keyword(s):  
Magnetic Field ◽  
Numerical Analysis ◽  
Poiseuille Flow ◽  
Conducting Fluid ◽  
Generation Process ◽  
Magnetic Field Generation ◽  
Electrically Conducting ◽  
Field Generation ◽  
Electrically Conducting Fluid ◽  
The Magnetic Field

Mechanisms for magnetic field reversals

2010 ◽  
Vol 368 (1916) ◽  
pp. 1595-1605 ◽  
Author(s):  
F. Pétrélis ◽  
S. Fauve
Keyword(s):  
Magnetic Field ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Large Scale ◽  
Conducting Fluid ◽  
Similar Model ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Simple Mechanism ◽  
The Magnetic Field

We present a review of the different models that have been proposed to explain reversals of the magnetic field generated by a turbulent flow of an electrically conducting fluid (fluid dynamos). We then describe a simple mechanism that explains several features observed in palaeomagnetic records of the Earth’s magnetic field, in numerical simulations and in a recent dynamo experiment. A similar model can also be used to understand reversals of large-scale flows that often develop on a turbulent background.

Effect of Magnetic Field on Free Convection in Inclined Cylindrical Annulus Containing Molten Potassium

2015 ◽  
Vol 07 (04) ◽  
pp. 1550052 ◽  
Author(s):  
Masoud Afrand ◽  
Nima Sina ◽  
Hamid Teimouri ◽  
Ali Mazaheri ◽  
Mohammad Reza Safaei ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Hartmann Number ◽  
Conducting Fluid ◽  
Electrically Conducting ◽  
Cylindrical Annulus ◽  
Electrically Conducting Fluid ◽  
Wide Range ◽  
The Magnetic Field

Three-dimensional (3D) numerical simulation of natural convection of an electrically conducting fluid under the influence of a magnetic field in an inclined cylindrical annulus has been performed. The inner and outer cylinders are maintained at uniform temperatures and other walls are thermally insulated. The governing equations of this fluid system are solved by a finite volume (FV) code based on SIMPLER solution scheme. Detailed numerical results of heat transfer rate, Lorentz force, temperature and electric fields have been presented for a wide range of Hartmann number (0 ≤ Ha ≤ 60) and inclination angle (0 ≤ γ ≤ 90). The results indicate that a magnetic field can control the magnetic convection of an electrically conducting fluid. Depending on the direction and strength of the magnetic field, the suppression of convective motion was observed. For vertical cylindrical annulus, increasing the strength of the magnetic field causes the loss symmetry, and as the consequence, isotherms lose their circular shape. With increasing the Hartmann number the average Nusselt number approaches a constant value. For vertical annulus, the effect of Hartmann number on the average Nusselt number is not prominent compared to the case of horizontal annulus.

On the motion of a rigid cylinder in a rotating electrically conducting fluid

1994 ◽  
Vol 260 ◽  
pp. 299-314 ◽  
Author(s):  
David E. Loper
Keyword(s):  
Magnetic Field ◽  
Force Balance ◽  
Conducting Fluid ◽  
Flow Structures ◽  
Coriolis Forces ◽  
Rigid Cylinder ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
The Magnetic Field ◽  
Lines Of Force

The flow structures generated and drag experienced by a rigid cylinder moving in an arbitrary direction through a rotating electrically conducting fluid in the presence of an applied magnetic field are investigated, with he aim of understanding better the nature of the small-scale flow in the core of the Earth which may be responsible for maintaining the geomagnetic field through dynamo action. Three cases are considered in the limit of small Rossby and magnetic Reynolds numbers. In the case of very weak rotation, the possible flow structures consist of a thin Hartmann layer and a long wake extending in the direction of the magnetic field, in which Lorentz and viscous forces balance, but only the long wake plays a dynamical role. The dominant drag force is experienced for motion that cuts magnetic lines of force. Motion of the cylinder parallel to its axis induces a much weaker drag, while that in the direction of the magnetic field induces none to dominant order. The cylinder also experiences weak lateral forces due to the Coriolis effect. In the case of weak rotation, the balance in the long wake is now magnetostrophic: between Lorentz and Coriolis forces. The drag is qualitatively identical to that in the first case, but the drag induced by motion parallel to the axis of the cylinder is increased, though still smaller than that for motions cutting magnetic lines of force. In the case of strong rotation, the flow structures consist of a thin Ekman layer and a foreshortened Taylor column extending in the direction of the rotation axis. In this column, the force balance is again magnetostrophic. Again only the large-scale structure plays a dynamical role. Motion of the cylinder perpendicular to its axis induces a larger drag than does motion parallel to its axis. The cylinder also experiences large lateral Coriolis forces.

scholarly journals DEPENDENCE OF THE MAGNETIC FIELD GENERATION MODELS OF IN MODEL OF A αΩ-DYNAMO ON THE INTENSITY OF A POWER TYPE α GENERATOR

2019 ◽  
pp. 58-66
Author(s):  
А.Н. Годомская ◽  
О.В. Шереметьева
Keyword(s):  
Magnetic Field ◽  
Comparative Analysis ◽  
Velocity Field ◽  
Dynamic Model ◽  
Radial Component ◽  
Magnetic Field Generation ◽  
Power Type ◽  
Exponential Kernel ◽  
Field Generation ◽  
The Magnetic Field

В динамической модели -динамо с переменной интенсивностью -генератора моделируются инверсии магнитного поля. Изменение интенсивности -генератора как следствие синхронизации высших мод поля скоростей и магнитного поля регулируется функцией Z(t) со степенным ядром. Получены режимы динамо для двух видов радиальной составляющей в скалярной параметризации -эффекта. Проведён анализ результатов в зависимости от изменения показателя степени ядра функции Z(t), а также сравнительный анализ с результатами исследования 10, где использовано показательное ядро функциии Z(t). In the dynamic model -dimensions are simulated reversions of the magnetic field with a varying intensity of the -generator. The change of the -generator intensity as a result of synchronization of higher modes of the velocity field and the magnetic field is regulated by a function Z(t) with a power kernel. Dynamo modes are obtained for two types of radial component in the scalar parameterization of the -effect. The results were analyzed depending on the change in the exponent of the kernel of the function Z(t), also a comparative analysis with the results of the study 10, where the exponential kernel of the function Z(t) was used.

Magnetisation of partially ionised dusty disks

2001 ◽  
Vol 66 (3) ◽  
pp. 213-222 ◽  
Author(s):  
GUIDO T. BIRK ◽  
A. KOPP ◽  
H. LESCH
Keyword(s):  
Magnetic Field ◽  
Circumstellar Disks ◽  
The Self ◽  
Charged Dust ◽  
Generation Process ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Neutral Gas ◽  
Fluid Velocities ◽  
Dust Component

The self-magnetisation of circumstellar disks is considered within an appropriate multifluid description. These disks are composed of ionised and neutral gas as well as of a charged dust component. The most important equation in this context is the general Ohm’s law that includes a magnetic field generation term due to relative dust–neutral fluid velocities. We show that circumstellar disks can carry their own significant magnetic fields. As long as the stellar gravitation sustains the accretion flow, the self-magnetisation of the disk does not saturate until the field strength reaches its local equipartition value. The magnetic field generation process is illustrated by idealised multifluid simulations that are not restricted to a kinematic description, but model the process in a self-consistent way.

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