Numerical study of the magnetic field diffusion in the toroidal field coils of the TFTR

Purpose – The analysis of the flow field and heat transfer around a tube row or tube banks wrapped with porous layer have many related engineering applications. Examples include the reactor safety analysis, combustion, compact heat exchangers, solar power collectors, high-performance insulation for buildings and many another applications. The purpose of this paper is to perform a numerical study on flows passing through two circular cylinders in side-by-side arrangement wrapped with a porous layer under the influence of a magnetic field. The authors focus the attention to the effects of magnetic field, Darcy number and pitch ratio on the mechanism of convection heat transfer and flow structures. Design/methodology/approach – The Darcy-Brinkman-Forchheimer model for simulating the flow in porous medium along with the Maxwell equations for providing the coupling between the flow field and the magnetic field have been used. Equations with the relevant boundary conditions are numerically solved using a finite volume approach. In this study, Stuart and Darcy numbers are varied within the range of 0 < N < 3 and 1e-6 < Da < 1e-2, respectively, and Reynolds and Prandtl numbers are equal to Re=100 and Pr=0.71, respectively. Findings – The results show that the drag coefficient decreases for N < 0.6 and increases for N > 0.6. Also, the effect of magnetic field is negligible in the gap between two cylinders because the magnetic field for two cylinders counteracts each other in these regions. Originality/value – To the authors knowledge, in the open literature, flow passing over two circular cylinders in side-by-side arrangement wrapped with a porous layer has been rarely investigated especially under the influence of a magnetic field.

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Numerical Study of Paramagnetic Elliptical Microparticles in Curved Channels and Uniform Magnetic Fields

Micromachines ◽

10.3390/mi11010037 ◽

2019 ◽

Vol 11 (1) ◽

pp. 37 ◽

Cited By ~ 1

Author(s):

Christopher Sobecki ◽

Jie Zhang ◽

Cheng Wang

Keyword(s):

Magnetic Field ◽

Numerical Study ◽

Spherical Particles ◽

Biological Applications ◽

Arbitrary Lagrangian Eulerian ◽

Curved Channel ◽

Radial Migration ◽

Wall Distance ◽

Curved Channels ◽

The Magnetic Field

We numerically investigated the dynamics of a paramagnetic elliptical particle immersed in a low Reynolds number Poiseuille flow in a curved channel and under a uniform magnetic field by direct numerical simulation. A finite element method, based on an arbitrary Lagrangian-Eulerian approach, analyzed how the channel geometry, the strength and direction of the magnetic field, and the particle shape affected the rotation and radial migration of the particle. The net radial migration of the particle was analyzed after executing a π rotation and at the exit of the curved channel with and without a magnetic field. In the absence of a magnetic field, the rotation is symmetric, but the particle-wall distance remains the same. When a magnetic field is applied, the rotation of symmetry is broken, and the particle-wall distance increases as the magnetic field strength increases. The causation of the radial migration is due to the magnetic angular velocity caused by the magnetic torque that constantly changes directions during particle transportation. This research provides a method of magnetically manipulating non-spherical particles on lab-on-a-chip devices for industrial and biological applications.

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

Processes ◽

10.3390/pr8030258 ◽

2020 ◽

Vol 8 (3) ◽

pp. 258 ◽

Cited By ~ 6

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.

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Electromagnetic wave backscattering across a magnetic field in a bounded plasma

Journal of Plasma Physics ◽

10.1017/s0022377800009946 ◽

1979 ◽

Vol 22 (1) ◽

pp. 85-96

Author(s):

Joseph E. Willett ◽

Sinan Bilikmen ◽

Behrooz Maraghechi

Keyword(s):

Magnetic Field ◽

Numerical Study ◽

Magnetized Plasma ◽

Absolute Instability ◽

Moment Equations ◽

Homogeneous Plasma ◽

Coupled Equations ◽

Bounded Plasma ◽

The Moment ◽

The Magnetic Field

The stimulated backscattering of electromagnetic ordinary waves from extraordinary waves propagating normal to a magnetic field in a plasma of finite length is studied. A pair of coupled differential equations for the amplitudes of the backscattered and scatterer waves is derived from Maxwell's equations and the moment equations for an inhomogeneous magnetized plasma. Solution of the coupled equations for a homogeneous plasma yields an expression for the growth rate of the absolute instability as a function of plasma length and damping rates of the product waves. The convective regime in which only spatial amplification occurs is discussed. A numerical study of the effects of the magnetic field on Raman and Brillouin backscattering is presented.

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Numerical study of toroidal magnetic field on the self-gravitating protoplanetary disks

International Journal of Modern Physics D ◽

10.1142/s0218271820500674 ◽

2020 ◽

Vol 29 (09) ◽

pp. 2050067

Author(s):

Hanifeh Ghanbarnejad ◽

Maryam Ghasemnezhad

Keyword(s):

Magnetic Field ◽

Accretion Disks ◽

Numerical Solutions ◽

Numerical Study ◽

Ohmic Heating ◽

The Self ◽

Toroidal Magnetic Field ◽

Heating Process ◽

Heating And Cooling ◽

The Magnetic Field

In this paper, we study the self-gravitating accretion disks by considering the toroidal component of magnetic field, [Formula: see text] and wind/outflow in the flow and also investigate the effect of two parameters, [Formula: see text] and [Formula: see text] corresponding to magnetic field on the latitudinal structure of such accretion disks. The cooling of the disk is parameterized simply as, [Formula: see text] (where [Formula: see text] is the internal energy and [Formula: see text] is the cooling timescale and [Formula: see text] is a free constant) and the heating rate is decomposed into two components, magnetic field and viscosity dissipations. We have shown that when the toroidal magnetic field becomes stronger, the heating process (viscous and resistivity) and the radiative cooling rate increase. Ohmic heating is much bigger than viscous heating and cooling, so we must consider the role of the magnetic field in the energy equation. Our numerical solutions show that the thickness of the disk decreases with strong toroidal component of magnetic field. The magnetic field leads to production of the outflow in the low latitude. So, by increasing the toroidal component of the magnetic field, the regions which belong to inflow decrease and the disk is cooled.

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On the magnetic field diffusion in mhd modeling of the inner coma of comet halley

Geophysical & Astrophysical Fluid Dynamics ◽

10.1080/03091929808213650 ◽

1998 ◽

Vol 89 (1-2) ◽

pp. 145-168 ◽

Cited By ~ 1

Author(s):

M. D. Kartalev ◽

V. I. Nikolova

Keyword(s):

Magnetic Field ◽

Field Diffusion ◽

Mhd Modeling ◽

Comet Halley ◽

The Magnetic Field

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Solar Dynamo

Oxford Research Encyclopedia of Physics ◽

10.1093/acrefore/9780190871994.013.11 ◽

2020 ◽

Author(s):

Robert Cameron

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Magnetic Flux ◽

Differential Rotation ◽

Large Scale ◽

Toroidal Field ◽

Solar Dynamo ◽

Small Scale ◽

The Sun ◽

The Magnetic Field

The solar dynamo is the action of flows inside the Sun to maintain its magnetic field against Ohmic decay. On small scales the magnetic field is seen at the solar surface as a ubiquitous “salt-and-pepper” disorganized field that may be generated directly by the turbulent convection. On large scales, the magnetic field is remarkably organized, with an 11-year activity cycle. During each cycle the field emerging in each hemisphere has a specific East–West alignment (known as Hale’s law) that alternates from cycle to cycle, and a statistical tendency for a North-South alignment (Joy’s law). The polar fields reverse sign during the period of maximum activity of each cycle. The relevant flows for the large-scale dynamo are those of convection, the bulk rotation of the Sun, and motions driven by magnetic fields, as well as flows produced by the interaction of these. Particularly important are the Sun’s large-scale differential rotation (for example, the equator rotates faster than the poles), and small-scale helical motions resulting from the Coriolis force acting on convective motions or on the motions associated with buoyantly rising magnetic flux. These two types of motions result in a magnetic cycle. In one phase of the cycle, differential rotation winds up a poloidal magnetic field to produce a toroidal field. Subsequently, helical motions are thought to bend the toroidal field to create new poloidal magnetic flux that reverses and replaces the poloidal field that was present at the start of the cycle. It is now clear that both small- and large-scale dynamo action are in principle possible, and the challenge is to understand which combination of flows and driving mechanisms are responsible for the time-dependent magnetic fields seen on the Sun.

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Numerical Study of Periodic Magnetic Field Effect on 3D Natural Convection of MWCNT-Water/Nanofluid with Consideration of Aggregation

Processes ◽

10.3390/pr7120957 ◽

2019 ◽

Vol 7 (12) ◽

pp. 957 ◽

Cited By ~ 5

Author(s):

Lioua Kolsi ◽

Hakan Oztop ◽

Kaouther Ghachem ◽

Mohammed Almeshaal ◽

Hussein Mohammed ◽

...

Keyword(s):

Magnetic Field ◽

Numerical Study ◽

Three Dimensional ◽

Magnetic Field Effect ◽

Oscillation Period ◽

Governing Equations ◽

Periodic Magnetic Field ◽

Aggregation Effect ◽

Volume Method ◽

The Magnetic Field

In this paper, a numerical study is performed to investigate the effect of a periodic magnetic field on three-dimensional free convection of MWCNT (Mutli-Walled Carbone Nanotubes)-water/nanofluid. Time-dependent governing equations are solved using the finite volume method under unsteady magnetic field oriented in the x-direction for various Hartmann numbers, oscillation periods, and nanoparticle volume fractions. The aggregation effect is considered in the evaluation of the MWCNT-water/nanofluid thermophysical properties. It is found that oscillation period, the magnitude of the magnetic field, and adding nanoparticles have an important effect on heat transfer, temperature field, and flow structure.

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Numerical Study of a Vertical Solidification Process under Magnetic Field in Unsteady State

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.297-301.254 ◽

2010 ◽

Vol 297-301 ◽

pp. 254-262

Author(s):

Sabrina Nouri ◽

Mouhamed Benzeghiba ◽

Ahmed Benzaoui

Keyword(s):

Magnetic Field ◽

Binary Alloy ◽

Numerical Study ◽

Magnetic Field Effect ◽

Solidification Process ◽

Computer Code ◽

Thermosolutal Convection ◽

Unsteady State ◽

Vertical Solidification ◽

The Magnetic Field

Numerical computation is achieved in an axisymmetric configuration to analyze the magnetic field effect on thermosolutal convection during vertical solidification of a binary alloy. The bath is exposed to a uniform temperature profile in unsteady state. During the growth three regions appear: liquid, mushy and solid zones. The mushy zone is assimilated to porous medium. A mathematical model of heat, momentum and solute transfer has been developed in primitive variables (pressure-velocity). A single domain approach (enthalpy method) is used to build the equations system. In this context, a computer code has been developed and validated with previous studies. The results in term of stream function and solute concentration show the strong effect of the magnetic field on the fluid flow and on the solutal stratification. The effects of magnetic field and melt convection intensity were demonstrated. The main results show that the quality of highly doped binary alloy crystals can be improved when the growth process occurs at low pulling rates and under a magnetic field.

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