Numerical Analysis of Air Convection in a Vertical Cylindrical Container With and Without a Gravitational Field Under a Gradient of a Magnetic Field

2002 ◽  
Author(s):  
Masato Akamatsu ◽  
Mitsuo Higano ◽  
Yoshio Takahashi ◽  
Hiroyuki Ozoe
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Transfer Rate ◽  
Relative Orientation ◽  
Axial Position ◽  
Cylindrical Container ◽  
Gravitational Fields ◽  
Air Convection ◽  
Magnetizing Force ◽  
The Magnetic Field

Two-dimensional numerical computations were carried out for natural convection of air in a vertical cylindrical container with and without a gravitational field under a gradient of a magnetic field. The magnetic field and the magnetizing force were induced in the cylinder area and the strength and the vectors of the magnetizing force were dependent on the axial location of the electric coil. Sample computations were carried out by changing the relative orientation of an electric coil and container. In a gravitational field, air in a cylindrical container was driven by both gravitational and magnetizing forces. On the other hand, the air flow was induced by the magnetizing force even in a non-gravitational field. Flow pattern and the heat transfer rate greatly depended on the axial position of the electric coil under both gravitational and non-gravitational fields.

The Control of Aerial Flow by the Magnetizing Force

2003 ◽  
Author(s):  
Masato Akamatsu ◽  
Mitsuo Higano ◽  
Yoshio Takahashi ◽  
Hiroyuki Ozoe
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Axial Position ◽  
Two Dimensional ◽  
Cylindrical Container ◽  
Gravitational Fields ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Magnetizing Force

Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force for air in a vertical cylindrical container with the thermal and magnetic field gradients under gravitational and non-gravitational fields. Several axial position of the electric coil was tested for numerical computation. In a vertical cylindrical container with the stagnant conduction and the Benard conditions, the aerial flow was able to be controlled by the magnetizing force under both gravitational and non-gravitational fields. The flow pattern and the heat transfer rate strongly depended on the axial position of the electric coil.

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

scholarly journals The relative orientation between the magnetic field and gas density structures in non-gravitating turbulent media

2020 ◽  
Vol 499 (4) ◽  
pp. 4785-4792
Author(s):  
Bastian Körtgen ◽  
Juan D Soler
Keyword(s):  
Magnetic Field ◽  
Molecular Clouds ◽  
Relative Orientation ◽  
Local Magnetic Field ◽  
Gas Formation ◽  
Initial Magnetization ◽  
The Galaxy ◽  
Dynamical Time ◽  
Isothermal Gas ◽  
The Magnetic Field

ABSTRACT Magnetic fields are a dynamically important agent for regulating structure formation in the interstellar medium. The study of the relative orientation between the local magnetic field and gas (column-) density gradient has become a powerful tool to analyse the magnetic field’s impact on the dense gas formation in the Galaxy. In this study, we perform numerical simulations of a non-gravitating, isothermal gas, where the turbulence is driven either solenoidally or compressively. We find that only simulations with an initially strong magnetic field (plasma-β < 1) show a change in the preferential orientation between the magnetic field and isodensity contours, from mostly parallel at low densities to mostly perpendicular at higher densities. Hence, compressive turbulence alone is not capable of inducing the transition observed towards nearby molecular clouds. At the same high initial magnetization, we find that solenoidal modes produce a sharper transition in the relative orientation with increasing density than compressive modes. We further study the time evolution of the relative orientation and find that it remains unchanged by the turbulent forcing after one dynamical time-scale.

Effect of a Magnetic Field on the Heat Transfer Rate on Free Convection in a Rectangular Cavity

2005 ◽  
Author(s):  
Gustavo Gutierrez ◽  
Ezequiel Medici
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stokes Equations ◽  
Rectangular Cavity ◽  
Convection Flow ◽  
Interesting Phenomenon ◽  
The Magnetic Field

The interaction between magnetic fields and convection is an interesting phenomenon because of its many important engineering applications. Due to natural convection motion the electric conductive fluid in a magnetic field experiences a Lorenz force and its effect is usually to reduce the flow velocities. A magnetic field can be used to control the flow field and increase or reduce the heat transfer rate. In this paper, the effect of a magnetic field in a natural convection flow of an electrically conducting fluid in a rectangular cavity is studied numerically. The two side walls of the cavity are maintained at two different constant temperatures while the upper wall and the lower wall are completely insulated. The coupling of the Navier-Stokes equations with the Maxwell equations is discussed with the assumptions and main simplifications assumed in typical problems of magnetohydrodynamics. The nonlinear Lorenz force generates a rich variety of flow patterns depending on the values of the Grashof and Hartmann numbers. Numerical simulations are carried out for different Grashof and Hartmann numbers. The effect of the magnetic field on the Nusselt number is discussed as well as how convection can be suppressed for certain values of the Hartmann number under appropriate direction of the magnetic field.

Boiling heat transfer characteristics of binary magnetic fluid flow in a vertical circular pipe with a partly heated region

2004 ◽  
Vol 218 (2) ◽  
pp. 223-232 ◽  
Author(s):  
S Shuchi ◽  
K Sakatani ◽  
H Yamaguchi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Boiling Heat Transfer ◽  
Transfer Rate ◽  
Heated Region ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
The Magnetic Field

An investigation was conducted for heat transfer characteristics of binary magnetic fluid flow in a partly heated circular pipe experimentally. The boiling heat transfer characteristics on the effects of the relative position of the magnetic field to the heated region were particularly considered in the present study. From the experimental verification, the Nusselt number, representing boiling heat transfer characteristics, was obtained for various flow and magnetic conditions which were represented by the non-dimensional parameters of the Reynolds number and the magnetic pressure number. Additionally, the rate of change of the Nusselt number found by applying the magnetic field was also estimated and the optimal position of the field to the partly heated region was discussed. The results indicated that the effect of the magnetic field to the heat transfer rate from the heated wall was mainly subjected to the effect of the vortices induced in the magnetic field region and the possibility of controlling the heat transfer rate by applying an outer magnetic field to utilize the effect.

scholarly journals 3D Magneto-Buoyancy-Thermocapillary Convection of CNT-Water Nanofluid in the Presence of a Magnetic Field

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 258 ◽  
Author(s):  
Lioua Kolsi ◽  
Salem Algarni ◽  
Hussein A. Mohammed ◽  
Walid Hassen ◽  
Emtinene Lajnef ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Flow Structure ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Stabilization ◽  
Magnetic Field Magnitude ◽  
The Magnetic Field

A numerical study is performed to investigate the effects of adding Carbon Nano Tube (CNT) and applying a magnetic field in two directions (vertical and horizontal) on the 3D-thermo-capillary natural convection. The cavity is differentially heated with a free upper surface. Governing equations are solved using the finite volume method. Results are presented in term of flow structure, temperature field and rate of heat transfer. In fact, results revealed that the flow structure and heat transfer rate are considerably affected by the magnitude and the direction of the magnetic field, the presence of thermocapillary forces and by increasing nanoparticles volume fraction. In opposition, the increase of the magnetic field magnitude leads to the control the flow causing flow stabilization by merging vortexes and reducing heat transfer rate.

scholarly journals Rapidly Evolving Structures in the Photosphere of the Mira Variable TX Cam

2001 ◽  
Vol 205 ◽  
pp. 252-255 ◽  
Author(s):  
P. J. Diamond ◽  
A. J. Kemball
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Shock Waves ◽  
Circumstellar Envelope ◽  
Structural Variations ◽  
Mira Variable ◽  
The Magnetic Field ◽  
Dynamical Mode

44 VLBA observations of the 43 GHz SiO masers in the circumstellar envelope surrounding the Mira variable TX Cam reveal dramatic structural variations over the 80 week stellar cycle. The dominant dynamical mode is one of expansion although other complex motions are visible. The gravitational field of the star does not have a significant effect on the dynamics observed, these are probably governed more by the magnetic field and the effects of the shock waves resulting from the pulsation of the Mira itself.

Numerical Simulation of Magneto-Convection in an Enclosure

2009 ◽  
Author(s):  
M. Ghassemi ◽  
M. Pirmohammadi
Keyword(s):  
Magnetic Field ◽  
Rayleigh Number ◽  
Convective Flow ◽  
Transfer Rate ◽  
Temperature Fields ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Molten Sodium ◽  
Linear Differential ◽  
The Magnetic Field

Natural-convection flow in the presence of a magnetic field in an enclosure heated from bottom and cooled from top is considered. The fluid (molten sodium) properties are function of temperature. To solve the governing non-linear differential equations (mass, momentum and energy) a finite volume code based on PATANKAR’s SIMPLER method is utilized. The results for different Rayleigh and Hartmann numbers show that the strength of the magnetic field has significant effects on the flow and temperature fields. The convection becomes stronger as the Rayleigh number increases while the magnetic field suppresses the convective flow and the heat transfer rate. When the magnetic field is weak and the Rayleigh number is high, the convection is dominant.

scholarly journals DEVICE FOR RESEARCHES OF MAGNETIC FIELD IMPACT UPON “WHEEL-RAIL” FRICTION PAIR CHARACTERISTICS

2020 ◽  
Vol 2020 (1) ◽  
pp. 34-39
Author(s):  
Dmitriy Antipin ◽  
Vladimir Vorob'ev ◽  
Maksim Maslov ◽  
Vadim Korchagin
Keyword(s):  
Magnetic Field ◽  
Friction Pair ◽  
Point Contact ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Original Design ◽  
Magnetic Conductor ◽  
Magnetizing Force ◽  
The Impact ◽  
The Magnetic Field

The paper is dedicated to the circuit diagram substantiation of the specialized roller bench for researches of the magnetic field impact upon wheel adhesion with a rail. On the basis of the analysis of the experimental plants available at present for the study of the contact interaction of wheels with rails it is defined that two-roller benches are the most efficient for the investigation of different outer factors impact upon wheel adhesion with a rail. Taking into account mentioned above there is offered an original design of the two-roller bench equipped with the device for friction area magnetization. Two cylinders with parallel axes are theoretically a friction pair. Taking into account the presence of a non-concurrency arisen at roller manufacturing and mounting a point contact is realized in the bench. A bench formation is carried out according to a modular approach with the installation of rotary magnetic conductors. For the support of the largest magnetization of a friction area in longitudinal and transverse directions and for the decrease of stray flux in the bench there is realized a series connection of roller friction area with the sources of a magnetizing force. For the substantiation of rotary magnetic conductor position choice regarding a friction area of bench rollers there is carried out an analysis of magnetic field distribution in the friction area depending on the location of magnetic conductors. On the basis of the investigation results it is defined that a change of magnetic conductor position changes the orientation of a magnetic field vector, at that a roller friction area is magnetized in transverse and longitudinal directions. In view of this the bench design offered allows investigating the impact of longitudinal and cross magnetic fields upon friction in the contact of a wheel with a rail. Furthermore, it is defined that at small values of an angle between the direction of a magnetic field vector and the plane of a roller friction area a possibility to exclude the effect of roller magnetic additional loading appears.

scholarly journals Generalization of the Particle Spin as it Ensues from the Ether Theory

2016 ◽  
Vol 8 (4) ◽  
pp. 58
Author(s):  
David Zareski
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Elasticity Theory ◽  
Gravitational Potential ◽  
Electric Charge ◽  
Neutral Particle ◽  
Circularly Polarized ◽  
Ether Theory ◽  
The Magnetic Field ◽  
Potential Tensor

In previous papers we generalized the ether waves associated to photons, to waves generally denoted  , associated to Par(m,e)s, (particles of mass m and electric charge e), and demonstrated that a Par(m,e)s is a superposition   of such waves that forms a small globule moving with the velocity   of this  . That, at a point near to a moving  , the ether velocity  , i.e., the magnetic field H, is of the same form as that of a point of a rotating solid. This is the spin of the Par(m,e)s, in particular, of the electron. Then, we considered the case where e=0 and showed that the perturbation caused by the motion of a Par(m,e)s is also propagated in the ether, and is a propagating gravitational field such that the Newton approximation (NA) is a tensor  Guobtained by applying the Lorenz transformation for Vm,o on the NA of the static gravitational potential of forces Gu,s. It appeared that Gu is also of the form of a Lienard-Wiechert potential tensor Au created by an electric charge.<br />In the present paper, we generalized the above results regarding the spin by showing that the ether elasticity theory implies also that like the electron, the massive neutral particle possesses a spin but much smaller than that of the electron, and that the photon can possess also a spin, when for example it is circularly polarized. In fact, we show that the spin associated to a particle is a vortex in ether which in closed trajectories will take only quantized values.<br /><br />

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