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This paper describes numerical magnetohydrodynamic (MHD) calculation of heat plasma used in heating and welding processes. Most of the calculation models have been two dimensional and static. Since physical phenomena are three dimensional and nonstatic, three dimensional, dynamic MHD calculation of heat plasma is developed in this paper. Since local heat balance is assumed, the heat plasma is considered as a conductive fluid dynamic material such as molten metal. However, heat plasma's material constants such as density, heat transfer coefficient, specific heat, and electrical conductivity are strong functions of the temperature. Temperature is governed by heat plasma material transfer and heat transfer. Material transfer is driven by the electromagnetic force. Turbulent flow is modeled by the large eddy simulator including heat transfer. The electrical phenomenon is modeled using the Poisson equation in a dc magnetic field. It is assumed that the static electrical force may be ignored. Calculations show that the heat plasma concentrates at the center. The center area is of low density and high electrical conductivity. To verify the usefulness of this 3D dynamic MHD method, a conventional model, which is 2D and static is compared to a k-ε model. Comparison of velocity distributions shows good agreement. [ABSTRACT FROM AUTHOR]

The estimate of free surface velocity at the billet mold in magnetohydrodynamic calculation is important for steel surface quality. It is considered that the free surface velocity in the electromagnetic stirring operation is transferred through the wall, a boundary of the molten steel. Then the wall friction phenomena between the wall and the molten steel are modeled so as a wall friction, force is a function of wall velocity. The calculated velocity distribution in consideration of the wall friction in which the friction coefficient is estimated as 0.03 is in good agreement with the measured value. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In the continuous casting process, it is very important to make the dynamic behavior of free surface of molten steel clear, because surface quality of steel is almost decided by conditions of free surface. The conventional MHD calculation, which has been used to design the process, was using only the constant electromagnetic force in the time. Then, we developed new MHD calculation also taking the cyclic electromagnetic force into account, and confirmed that free surface vibrates more intensely than conventional result. Therefore, to make the dynamic behavior of free surface clear, cyclic electromagnetic force must be considered. [ABSTRACT FROM AUTHOR]

A 3-D Magnetohydrodynamic calculation in consideration of mold heat transfer is developed to obtain the precise mold thermal flux and the mold design. By means of modeling the heat transfer coefficient between the solidified steel and the copper mold in casting direction distribution, the temperature distribution in the mold is in good agreement with the operating data. The mold temperature at the meniscus position is higher than the others. From the cross section temperature at the mold, the corner is higher than the center position. [ABSTRACT FROM AUTHOR]

It is made clear why the pulse electromagnetic casting (EMC) makes the surface steel quality good from the point of view of fluid dynamics by means of magnetohydrodynamic calculation with shadow method. In order to obtain good surface quality, the free surface profile should follow the pulse electromagnetic force and fluid dynamics are stable and uniform for the rectangular axis. By means of the pulse mode in EMC operation, the fluid dynamics make stable and uniform the unstable flow in continuous EMC operation and the free surface profile is maintained as convex. [ABSTRACT FROM AUTHOR]

Presents a study which used a magnetohydrodynamic calculation model to get the optimal operation of in-mold electromagnetic stirring taking into consideration heat transfer, solidification and free surface. Magnetohydrodynamic calculation; Electromagnetic analysis; Fluid dynamic analysis.

Abstract. 30 magnetohydrodynamic calculation model taking into consideration of heat transfer and solidification as well as free surface is developed in order to evaluate the characteristics of molten metal using electromagnetic stirring (EMS). A shadow method that calculates electromagnetic force in consideration of free surface transition is proposed to reduce computing time and keep sufficient accuracy. A calculated free surface of Mercury under 200 Hz magnetic field shows an adequate agreement with experimental one. Calculation results applied to continuous casting process taking into consideration of heat transfer and solidification are in good agreement with operation data. This model introduces that EMS makes the solidified shell uniform and dynamic deviation of temperature stable. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined a three-dimensional magneto-hydrodynamic method for evaluating the free surface motion of molten metal. Calculation method; Calculation results; Conclusions.

Presents information on a study which developed a three-dimensional magnetohydrodynamic calculation model for evaluating the characteristics of molten metal using electromagnetic stirring. Equation of heat transfer and solidification; Effect of the electromagnetic stirring; Calculation results; Conclusions.

Discusses how the magnetohydrodynamic calculation is use to get the optimal operation of in-mold electromagnetic stirring through the fundamental characteristics. System construction of in-mold electromagnetic stirring; Magnetohydrodynamic calculation; Conclusions.

We evaluate an effect of the dual in-mold electromagnetic stirring (M-EMS) which is arranged in series to control the molten steel velocity distribution using magnetohydrodynamic Calculation. A stirring force ratio (SFR) defined as Fu/F1 where Fu is an electromagnetic force of upper M-EMS and F1 is the one of the lower M-EMS is introduced as an index of input. The value of SFR at the optimal condition that meniscus velocity is almost zero, but some velocity is realized at lower M-EMS position. Especially, the SFR condition to have no velocity at free surface is extremely rigorous. This means that it is very difficult to be stable at meniscus by the dual M-EMS system. The lower velocity hardly changes when the SFR changes. [ABSTRACT FROM AUTHOR]

Shows the comparison between the experimental data and magnetohydrodynamic calculation data for electromagnetic stirring of molten metal. Calculation model; Comparison of molten metal materials; Conclusion.