When processed in an electromagnetic field, a conducting fluid such as molten metal or semiconductor melt interacts with the field to generate bulk motions in the liquid which, in turn, modify the field distribution. An understanding of this interactive behavior of the combined field/fluid system is of vital importance in controlling the properties of the materials to be processed. This dissertation studies the interaction between molten metals and field in the process of electromagnetic casting.; The fundamentals governing the coupling between the field and fluid motions are explored and formulated in the frame of relativistic theory. The equations of engineering magnetohydrodynamics are then derived by letting the relativistic formulation approach to its classical limit.; These classical equations are further exploited to develop a mathematical model of the interaction of molten metals with field for the electromagnetic casting of cylindrical ingots. Using this axisymmetric model, the electrodynamic and fluid-dynamic phenomena such as electric and magnetic field distribution, meniscus deformation and electromagnetically-driven flow are studied from the first principles. A physical model of cylindrical casters is constructed with the principal objective of testing the mathematical model. It comprises a pool of Wood's metal surrounded by inductors of various geometries which are powered by a 3 kHz generator at various currents. Magnetic and electric fields, meniscus shapes and melt velocities are measured by various probes under the control of a microcomputer. Results are presented for varying operational parameters under the control of the caster designer, such as inductor geometry and placement, input current and frequency, and screen placement, and show that a reasonable agreement exists between the predictions of the mathematical model and the experimental measurements.; As the axisymmetric model is two-dimensional in nature, a surface integral model is established to study the three-dimensional phenomena near the corner region of a near rectangular casting. The surface model makes use of the concept of surface currents which enables the embedding of fictious magnetic charges on the surface to simplify the otherwise very complicated problem mathematically. The results obtained by the model are presented for surface currents and for meniscus deformation in a three dimensional electromagnetic caster. A mathematical model of the 3D turbulent melt flow driven by the electromagnetic forces and a 3D physical model are called for, however, to further our understanding of the complex fluid motion near the corner region.
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