Computational MHD Part III — Application to Electromagnetic Control of Convective Flows

Abstract

Convective flow in a liquid metal heated locally at its upper surface and affected by an applied time-dependent magnetic field is investigated. The system under consideration serves as a physical model for the industrial process of electron beam evaporation of liquid metals. In this process, the strong energy input induces strong temperature gradients along the free surface and in the interior of the melt. Thus, the liquid metal is subject to both thermocapillary and natural convection. The vigorous convective motion within the melt leads to highly unwelcome heat losses through the walls of the crucible. The strong convective heat transfer limits the temperature rise in the hot spot and, therefore, the thermodynamic efficiency of the evaporation process. The present paper aims to demonstrate that the melt-flow can be effectively controlled by using external magnetic fields in order to considerably reduce the convective heat losses. As examples, we employ numerical simulations based on the finite element method to study the effects of both a traveling magnetic field and a rotating magnetic field.