The stability of an interface between viscous fluids subjected to a high-frequency magnetic field and consequences for electromagnetic casting

Abstract

The stability of an interface between inviscid fluids subjected to a high-frequency magnetic field has been examined previously by Garnier & Moreau (1983). The present paper extends that study to include the viscosity of both fluids in order to estimate the damping rates of the perturbations. Furthermore, Garnier & Moreau made an assumption that the frequency of oscillation of the interface could be neglected compared to the frequency of the applied field; they concluded that the applied field was not destabilizing. That (apparently reasonable) assumption has been lifted in the present work and the consequence is that the magnetic field is seen to lead to instability over a significant range of wavelengths. Application of this analysis to the electromagnetic casting of aluminium is discussed.

Free Surface Controlled by Magnetic Fields

“…This has been shown analytically in the case of a liquid metal semi-infinite pool submitted to a parallel single-frequency AC magnetic field. 15,16) Increasing the frequency suppresses the instability of surface waves perpendicular to the applied magnetic field; however, increasing the magnetic field strength may enhance it. 16) That effect is illustrated in Fig.…”

Numerical Simulation of High Frequency Electromagnetic Field in Soft Contact Continuous Casting Mold

“…It can improve the quality of billet. In the mold, the distribution of electromagnetic field directly affects the flow of molten steel, temperature field, the shape and stability of the meniscus [3][4][5] . Thus it affects the smooth of continuous casting process and the heat transfer of billet.…”

A mathematical model for the dynamic behavior of melts subjected to electromagnetic forces: Part I. model development and comparison of predictions with published experimental results

“…These authors concluded that the alternating field neither destabilizes, nor contributes to the stability of, the free surface. An analysis similar to that of Garnier and Moreau, but with two differences, was described by Deepak and Evans; [7] allowance was made for viscosity, and a simplifying assumption made by the former authors was avoided. Deepak and Evans concluded that, above a certain critical field (on the order of 0.05 Tesla for an aluminum pool at 3 kHz), the magnetic field destabilized the melt surface.…”