• 천문학회지
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• 제42권5호
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• pp.107-123
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• 2009

We investigate the wave properties for isothermal plasma state around to the de Sitter black hole's horizon using 3+1 split of spacetime. The corresponding Fourier analyzed perturbed perfect GRMHD equations are used to obtain the complex dispersion relations. We obtain the real values of the wave number k, from these relations, which are used to evaluate the quantities like phase and group velocities etc. These have been analyzed graphically in the neighborhood of the horizon.

• 천문학논총
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• 제7권1호
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• pp.71-77
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• 1992

An axisymmetric, stationary electrodynamic model of the central engine of an active galactic nucleus has been well formulated by Macdonald and Thorne. In this model the relativistic region around the central black hole must be filled by highly conducting plasma and the equations of magnetohydrodynamics are then satisfied. In this paper we analyze magnetohydrodynamic wave propagation in this region. We find that there are three distinct types of waves - the Alfven wave and two magnetosonic waves. The wave equations turn out to be not very different from those in nonrelativistic case except they are redshifted.

• 천문학회지
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• 제34권4호
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• pp.325-327
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• 2001

This poster summarizes numerical collapse calculations of non-rotating and rotating singular, isothermal toroids that employed the zeus2d (Norman and Stone 1992) magnetohydrodynamics package. In the non-rotating collapse calculations, it is seen that infall proceeds at a constant rate and magnetically supported, high density pseudo-disks form in the equatorial plane. With rotating clouds, however, toroidal magnetic fields grow as infall proceeds, teaming with angular momentum to slow the inflow to the center and generate outflow.

• 천문학회지
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• 제34권4호
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• pp.209-213
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• 2001

This paper describes the numerical solution to the hyperbolic system of magnetohydrodynamic (MHD) equations. First, by pointing out the approximations involved, the deal MHD equations are presented. Next, the MHD waves as well as the associated shocks and discontinuities, are presented. Then, based on the hyperbolicity of the ideal MHD equations, the application of upwind schemes, which have been developed for hydrodynamics, is discussed to solve the equations numerically. As an definite example, one and multi-dimensional codes based on the Total Variation Diminishing scheme are presented. The treatment in the multi-dimensional code, which maintains ${\nabla}{\cdot}$B = 0, is described. Through tests, the robustness of the upwind schemes for MHDs is demonstrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.691-692
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• 2006

The electromagnetic pump can transfer molten metals by the electromagnetic force of LIM for molten metals, which are zinc, tin and aluminum. The speed and quantity of the flow are analyzed using magnetohydrodynamics. The molten zinc is used in the experiment and the experimental results are compared with the analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3110-3115
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• 2007

The effect of Lorentz force(Electromagnetic force) on the liquid metal flow has been investigated. The flow velocity has been calculated by treating the Lorentz force as a source term in the Navier-Stokes equation. The liquid metal flow in the rectangular duct of an electromagnetic pump was analyzed with the Lorentz force varied.

• 천문학회보
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• 제40권2호
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• pp.38.1-38.1
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• 2015

Supernova remnants (SNRs) are one of the most energetic astrophysical events and are thought to be the dominant source of Galactic cosmic rays (CRs). A recent report on observations of gamma rays from the vicinity of SNRs have shown strong evidence that Galactic CR protons are accelerated by the shock waves of the SNRs. The actual gamma-ray emission from pion decay should depend on the diffusion of CRs in the interstellar medium. In order to quantitatively analyze the diffusion of high-energy CRs from acceleration sites, we have performed test particle numerical simulations of CR protons using a three-dimensional magnetohydrodynamics (MHD) simulation of an interstellar medium swept-up by a blast wave. We analyse the CRs diffusion at a length scale of order a few pc, and show the Richtmeyer-Meshkov instability can provide enough turbulence downstream of the shock to make the diffusion coefficient close to the Bohm level for energy larger than 30 TeV for a realistic interstellar medium.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1081-1096
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• 2011

In this paper, a steady axisymmetric MHD flow of two dimensional incompressible fluids is studied under the influence of a uniform transverse magnetic field. The governing equations are reduced to nonlinear boundary value problem by applying the integribility conditions. Optimal Homotopy Asymptotic Method (OHAM) is applied to obtain solution of reduced fourth order nonlinear boundary value problem. For comparison, the same problem is also solved by Variational Iteration Method (VIM).

• 설비공학논문집
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• 제23권1호
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• pp.23-31
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• 2011

An analysis has been conducted of the flow characteristics and pumping performance of a thermopneumatic micropump with electrically conducting fluid. In the present study, considered is a thermopneumatic micropump for electrically conducting fluids with electromagnetic resistance alternately exerted at the inlet and outlet by alternately applied magnetic fields. A model of Prescribed Deformation is used for the motion of the membrane. Here, the pumping performance of the micropump and flow characteristics of the electrically conducting fluid are investigated in the range of Hartmann number less than 30. The current numerical study shows that the net flow rate through the micropump is almost proportional to the strength of the applied magnetic field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.74-76
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• 2006

This paper presents the experiment and characteristics analysis of electromagnetic pump using linear induction motor(LIM). The electromagnetic pump is used to transfer the molten metals by electromagnetic force of LIM. The characteristics of LIM pump for molten metals: zinc, tin, aluminum are analysed solving the magnetohydrodynamics at constant magnetic flux. The molten zinc is used in the experiment and the experimental results are compared with the analysis.