Publisher Summary This chapter reviews that internal convection strongly influences alloy-solidification processes. Local cooling and solidification rates are affected by convection conditions, which, in turn, have a strong influence on the microstructural features of a casting. Moreover, advective transport of interdendritic liquid is responsible for macrosegregation. To improve solid/liquid-phase-change processes involving multicomponent materials, it is vital that engineers understand the convection conditions associated with the processes. However, obtaining a reliable knowledge base for guiding process improvements is made difficult by several complicating features associated with alloy solidification. The chapter highlights that single-domain models for binary solid/liquid-phase- change systems have contributed to enhancing the knowledge base, and the results of several computational studies were reviewed to demonstrate the potential of the models to predict convective transport phenomena for a wide variety of process conditions. Possible means of intelligently controlling alloy-solidification processes were discussed and the role of numerical simulation in developing control strategies was reviewed.

Convection heat and mass transfer in alloy solidification

A mathematical model for the analysis and design of inductively coupled plasma torches is presented. The model is based upon a solution of the electromagnetic vector potential equation and is capable of predicting the two‐dimensional velocity, temperature, and electromagnetic fields as well as the reaction kinetics inside the torch for any axisymmetric coil configuration. The model is used to study the effect of coil design on the thermal decomposition of silicon tetrachloride to silicon. The coil design is found to affect both the temperature field and the flow field and to have a significant effect on the reaction kinetics in the torch. It is demonstrated that through fundamental changes in the coil design it is possible to control the location of the reaction zone and to reduce silicon deposition on the wall of the reactor.

The effect of coil design on materials synthesis in an inductively coupled plasma torch

The paper describes a mathematical model which predicts the meniscus shape and melt flow in an electromagnetic caster. Computations were carried out for the two types of caster (with and without a screen to shape the magnetic field) in commercial use. The dependence of meniscus shape on parameters such as inductor geometry, placement, current, and frequency, as well as screen properties and placement, was determined. Calculated velocities showed agreement with measurements of other investigators on a physical model and an actual caster. The effect of an auxiliary low frequency inductor on melt flow was also computed.

Mathematical modeling of meniscus profile and melt flow in electromagnetic casters

Effects of electromagnetic stirring during the controlled solidification of tin

A mathematical representation is given for the turbulent fluid flow and energy transfer in an rf induction plasma. The flow and temperature fields are obtained through the solution of the two‐dimensional rotationally symmetric turbulent Navier–Stokes equations along with the energy and the one‐dimensional Maxwell’s equations for the electric and magnetic fields. The turbulent viscosity is determined using the standard k‐e model. Results are given for an argon plasma under atmospheric conditions. Different aspects of turbulent flows and their implications in rf plasmas are discussed. The results indicate the presence of both laminar and turbulent regimes in the same flow field. The effect of swirl in the plasma gas is to increase the overall turbulence level in the torch.

A turbulent flow model for the rf inductively coupled plasma

A mathematical representation for the electromagnetic force field and the fluid flow field in a coreless induction furnace is presented. The fluid flow field was represented by writing the axisymmetric turbulent Navier-Stokes equation, containing the electromagnetic body force term. The electromagnetic body force field was calculated by using a technique of mutual inductances. The kappa-epsilon model was employed for evaluating the turbulent viscosity and the resultant differential equations were solved numerically. Theoretically predicted velocity fields are in reasonably good agreement with the experimental measurements reported by Hunt and Moore; furthermore, the agreement regarding the turbulent intensities are essentially quantitative. These results indicate that the kappa-epsilon model provides a good engineering representation of the turbulent recirculating flows occurring in induction furnaces. At this stage it is not clear whether the discrepancies between measurements and the predictions, which were not very great in any case, are attributable either to the model or to the measurement techniques employed.

The turbulent recirculating flow field in a coreless induction furnace. A comparison of theoretical predictions with measurements

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N. El-Kaddah

Papers

The turbulent recirculating flow field in a coreless induction furnace. A comparison of theoretical predictions with measurements

The turbulent recirculating flow field in a coreless induction furnace. A comparison of theoretical predictions with measurements