Numerical study of parametric pumping current in mesoscopic systems in the presence of a magnetic field

AbstractA numerical study is presented that deals with the flow in the mold of a continuous slab caster under the influence of a DC magnetic field (electromagnetic brakes (EMBrs)). The arrangement and geometry investigated here is based on a series of previous experimental studies carried out at the mini-LIMMCAST facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The magnetic field models a ruler-type EMBr and is installed in the region of the ports of the submerged entry nozzle (SEN). The current article considers magnet field strengths up to 441 mT, corresponding to a Hartmann number of about 600, and takes the electrical conductivity of the solidified shell into account. The numerical model of the turbulent flow under the applied magnetic field is implemented using the open-source CFD package OpenFOAM®. Our numerical results reveal that a growing magnitude of the applied magnetic field may cause a reversal of the flow direction at the meniscus surface, which is related the formation of a “multiroll” flow pattern in the mold. This phenomenon can be explained as a classical magnetohydrodynamics (MHD) effect: (1) the closure of the induced electric current results not primarily in a braking Lorentz force inside the jet but in an acceleration in regions of previously weak velocities, which initiates the formation of an opposite vortex (OV) close to the mean jet; (2) this vortex develops in size at the expense of the main vortex until it reaches the meniscus surface, where it becomes clearly visible. We also show that an acceleration of the meniscus flow must be expected when the applied magnetic field is smaller than a critical value. This acceleration is due to the transfer of kinetic energy from smaller turbulent structures into the mean flow. A further increase in the EMBr intensity leads to the expected damping of the mean flow and, consequently, to a reduction in the size of the upper roll. These investigations show that the Lorentz force cannot be reduced to a simple damping effect; depending on the field strength, its action is found to be topologically complex.

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Numerical study on mixed convective flow of water‐based magnetite nanofluid through a wavy channel containing porous blocks under the effect of an oscillating magnetic field

ZAMM ‐ Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik ◽

10.1002/zamm.202000254 ◽

2021 ◽

Author(s):

Victor M. Job ◽

Sreedhara Rao Gunakala

Keyword(s):

Magnetic Field ◽

Convective Flow ◽

Numerical Study ◽

Wavy Channel ◽

Water Based ◽

Porous Blocks ◽

Oscillating Magnetic Field ◽

Mixed Convective Flow

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A TIEGCM numerical study of the source and evolution of ionospheric F-region tongues of ionization: Universal time and interplanetary magnetic field dependence

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2017.03.005 ◽

2017 ◽

Vol 156 ◽

pp. 87-96 ◽

Cited By ~ 7

Author(s):

Jing Liu ◽

Wenbin Wang ◽

Alan Burns ◽

Libo Liu ◽

Joe McInerney

Keyword(s):

Magnetic Field ◽

Interplanetary Magnetic Field ◽

Field Dependence ◽

Magnetic Field Dependence ◽

Numerical Study ◽

Universal Time ◽

F Region

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The statistical and numerical study of the global distribution of coronal plasma and magnetic field near 2.5Rs over a 10-year period

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2010.05.016 ◽

2010 ◽

Vol 72 (13) ◽

pp. 1008-1018 ◽

Cited By ~ 8

Author(s):

Fang Shen ◽

Xueshang Feng ◽

Changqing Xiang ◽

Wenbin Song

Keyword(s):

Magnetic Field ◽

Numerical Study ◽

Global Distribution ◽

Coronal Plasma

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Numerical Study of the Effect of Magnetic Fields on Melt-Crystal Interface-Deflection in Czochralski Crystal Growth

Heat Transfer: Volume 3 ◽

10.1115/ht2003-47534 ◽

2003 ◽

Cited By ~ 2

Author(s):

Lijun Liu ◽

Koichi Kakimoto

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Numerical Study ◽

Silicon Crystal ◽

Czochralski Growth ◽

Thermal Flow ◽

Interface Shape ◽

Convective Thermal ◽

And Control ◽

Crystal Interface

In order to control the impurity distribution and remove defects in a crystal grown in Czochralski growth for high quality crystals of silicon, it is necessary to study and control the melt-crystal interface shape, which plays an important role in control of the crystal quality. The melt-crystal interface interacts with and is determined by the convective thermal flow of the melt in the crucible. Application of magnetic field in the Czochralski system is an effective tool to control the convective thermal flow in the crucible. Therefore, the shape of the melt-crystal interface can be modified accordingly. Numerical study is performed in this paper to understand the effect of magnetic field on the interface deflection in Czochralski system. Comparisons have been carried out by computations for four arrangements of the magnetic field: without magnetic field, a vertical magnetic field and two types of cusp-shaped magnetic field. The velocity, pressure, thermal and electromagnetic fields are solved with adaptation of the mesh to the iteratively modified interface shape. The multi-block technique is applied to discretize the melt field in the crucible and the solid field of silicon crystal. The unknown shape of the melt-crystal interface is achieved by an iterative procedure. The computation results show that the magnetic fields have obvious effects on both the pattern and strength of the convective flow and the interface shape. Applying magnetic field in the Czochralski system, therefore, is an effective tool to control the quality of bulk crystal in Czochralski growth process.

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