• Journal of the Korean Mathematical Society
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• v.56 no.6
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• pp.1641-1654
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• 2019

In this paper we study the quasi-neutral limit of the compressible magnetohydrodynamic flows in the periodic domain ${\mathbb{T}}^3$ with the well-prepared initial data. We prove that the weak solution of the compressible magnetohydrodynamic flows governed by the Poisson equation converges to the strong solution of the compressible flow of magnetohydrodynamic flows as long as the latter exists.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.6 no.2
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• pp.63-73
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• 2002

The influence of unsteady boundary layer magnetohydrodynamic flow with thermal relaxation of perfectly conducting fluid, past a semi-infinite plate, is considered. The governing non linear partial differential equations are solved using the method of successive approximations. This method is used to obtain the solution for the unsteady boundary layer magnetohydrodynamic flow in the special form when the free stream velocity exponentially depends on time. The effects of Alfven velocity $\alpha$ on the velocity is discussed, and illustrated graphically for the problem.

• Bulletin of the Korean Mathematical Society
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• v.58 no.6
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• pp.1521-1537
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• 2021

In this paper we consider the global well-posedness of compressible magnetohydrodynamic system in ℝ^d with d ≥ 2, in the framework of the critical Besov spaces. We can show that if the initial data, the shear viscosity and the magnetic diffusion coefficient are small comparing with the volume viscosity, then the compressible magnetohydrodynamic system has a unique global solution. Our result improves the previous one by Danchin and Mucha [10] who considered the compressible Navier-Stokes equations.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1396-1404
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• 2017

The mathematical aspects of Dufour and Soret phenomena on the peristalsis of magnetohydrodynamic (MHD) Jeffrey liquid in a symmetric channel are presented. Fluid viscosity is taken variably. Lubrication approach has been followed. Results for the velocity, temperature, and concentration are constructed and explored for the emerging parameters entering into the present problem. The plotted quantities lead to comparative study between the constant and variable viscosities fluids. Graphical results indicate that for non-Newtonian materials, pressure gradient is maximum, whereas pressure gradient is slowed down for variable viscosity. Also both velocity and temperature in the case of variable viscosity are at maximum when compared with results for constant viscosity.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1636-1644
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• 2017

The main purpose of this article is to describe the magnetohydrodynamic stagnation point flow of Walter-B nanofluid over a stretching sheet. The phenomena of heat and mass transfer are based on the involvement of thermal radiation and chemical reaction. Characteristics of Newtonian heating are given special attention. The Brownian motion and thermophoresis models are introduced in the temperature and concentration expressions. Appropriate variables are implemented for the transformation of partial differential frameworks into sets of ordinary differential equations. Plots for velocity, temperature, and nanoparticle concentration are displayed and analyzed for governing parameters. The skin friction coefficient and local Nusselt and Sherwood numbers are studied using numerical values. The temperature and heat transfer rate are enhanced within the frame of the thermal conjugate parameter.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.93-99
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• 1998

We present a novel micropump of which pumping mechanism is based upon MHD (Magnetohydrodynamic) principle. The MHD micropump uses Lorentz force as pumping source. In the MHD micropump, Lorentz force is applied into initially stagnant conducting fluid to drive it in magnetic and electric field to flow in both directions. The performance of the MHD micropump is obtained by measuring the pressure head difference and flow rate as applied voltage changes from 10 to 60 V DC at 0.19 and 0.44 Tesla. The pressure head difference is 18 mm at 38 mA and the flow rate is 63 ${\mu}{\ell}$ /min at 1.8 mA when the inside diameter of inlet/outlet tube is 2 mm and the magnetic flux density is 0.44 Tesla.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.26 no.2
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• pp.76-107
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• 2022

In this paper, we study the temporal decay of global weak solutions to the inhomogeneous Hall-magnetohydrodynamic (Hall-MHD) equations. First, an approximation problem and its weak solutions are obtained via the Caffarelli-Kohn-Nirenberg retarded mollification technique. Then, we prove that the approximate solutions satisfy uniform decay estimates. Finally, using the weak convergence method, we construct weak solutions with optimal decay rates to the inhomogeneous Hall-MHD equations.

• Publications of The Korean Astronomical Society
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• v.7 no.1
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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.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.66.2-66.2
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• 2012

Building a relativistic magnetohydrodynamic (RMHD) code based on upwind scheme is a challenging project, because eigenvalues and eigenvectors are not yet analytically given. Here, we present analytic expressions for eigenvalues and eigenvectors in isothermal flows. And then we show tests performed with a code based on the total variation diminishing (TVD) scheme.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.231-236
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• 1993

The feasibility of Magnetohydrodynamic(MHD) Ship Propulsion using Superconduction Magnets is reviewed in light of relent advances in high-temperature superconducting. The propulsion using a screw propeller in the noise reduction has it's own limitation. The epochal noiseless MHD propulsion method which does not have this disadvantage is studying nowadays. The subject of a marine MHD as propulsion has been examined before and was found to be interesting because of relatively low magnetic flux densities. It is demonstrated that the MHD propulsion is technically interesting with high magnetic flux density. The development of large-scale magnets using the high-temperature superconductor now under development could make it practical to construct submersibles for high-speed and silent operation.