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.

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.

Two-Dimensional Excitons in Large Magnetic Field Gradients

2000 ◽  
Vol 178 (1) ◽  
pp. 33-38 ◽  
Author(s):  
F. Pulizzi ◽  
P.C.M. Christianen ◽  
J.C. Maan ◽  
T. Wojtowicz ◽  
G. Karczewski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Two Dimensional ◽  
Large Magnetic Field ◽  
Field Gradients ◽  
Magnetic Field Gradients

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

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.

PFG NMR and internal magnetic field gradients in plant-based materials

2002 ◽  
Vol 20 (7) ◽  
pp. 567-573 ◽  
Author(s):  
Nikolaus Nestle ◽  
Asal Qadan ◽  
Petrik Galvosas ◽  
Wolfgang Süss ◽  
Jörg Kärger
Keyword(s):  
Magnetic Field ◽  
Internal Magnetic Field ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Pfg Nmr

In silico study of spheroids fusion through magnetic field gradients

2021 ◽  
Author(s):  
Cristian F. Rodriguez ◽  
Laura Ortiz C. ◽  
Kevin A. Giraldo R. ◽  
Carolina Munoz C. ◽  
Juan C. Cruz
Keyword(s):  
Magnetic Field ◽  
In Silico ◽  
Field Gradients ◽  
In Silico Study ◽  
Magnetic Field Gradients

Effect of magnetic field-dependent thermal conductivity on natural convection of magnetic nanofluid inside a square enclosure

2019 ◽  
Vol 29 (4) ◽  
pp. 1466-1489 ◽  
Author(s):  
Mohammadhossein Hajiyan ◽  
Shohel Mahmud ◽  
Mohammad Biglarbegian ◽  
Hussein A. Abdullah ◽  
A. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Magnetic Nanofluid ◽  
Content Type ◽  
Square Enclosure ◽  
Field Dependent

Purpose The purpose of this paper is to investigate the convective heat transfer of magnetic nanofluid (MNF) inside a square enclosure under uniform magnetic fields considering nonlinearity of magnetic field-dependent thermal conductivity. Design/methodology/approach The properties of the MNF (Fe3O4+kerosene) were described by polynomial functions of magnetic field-dependent thermal conductivity. The effect of the transverse magnetic field (0 < H < 105), Hartmann Number (0 < Ha < 60), Rayleigh number (10 <Ra <105) and the solid volume fraction (0 < φ < 4.7%) on the heat transfer performance inside the enclosed space was examined. Continuity, momentum and energy equations were solved using the finite element method. Findings The results show that the Nusselt number increases when the Rayleigh number increases. In contrast, the convective heat transfer rate decreases when the Hartmann number increases due to the strong magnetic field which suppresses the buoyancy force. Also, a significant improvement in the heat transfer rate is observed when the magnetic field is applied and φ = 4.7% (I = 11.90%, I = 16.73%, I = 10.07% and I = 12.70%). Research limitations/implications The present numerical study was carried out for a steady, laminar and two-dimensional flow inside the square enclosure. Also, properties of the MNF are assumed to be constant (except thermal conductivity) under magnetic field. Practical implications The results can be used in thermal storage and cooling of electronic devices such as lithium-ion batteries during charging and discharging processes. Originality/value The accuracy of results and heat transfer enhancement having magnetic field-field-dependent thermal conductivity are noticeable. The results can be used for different applications to improve the heat transfer rate and enhance the efficiency of a system.

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