Chaotic mixing in a Joule-heated glass melt

Abstract

A numerical study of two-dimensional thermal convection of a highly viscous fluid driven by volumetric heating has been carried out to investigate the effect of time-dependent thermal forcing on the degree of mixing. The problem is relevant to electrically heated glass melting furnaces which are traditionally operated with time-independent heating. The numerical computations carried out are for two model fluids representing semitransparent and opaque melts, respectively. Lagrangian motion of passive tracers is numerically simulated and degree of mixing in the glass melt is quantified in terms of mixing entropy. The computed flow patterns indicate that time-dependent streamlines intersect transversely and, thereby, result in well-mixed regions. The stirring mechanism involves the rotational stretching and folding produced by two oscillating vortices with varying size and circulation. The model predictions indicate that the chaotic mixing is strongly dependent on the period of electrode firing cycle. The present investigation demonstrates that time-dependent thermal forcing improves the mixing characteristics of both semitransparent and opaque glass melts significantly.

Energy spectra and turbulence generation in the wake of magnetic obstacles

“…The interaction between flows of electrically conducting fluids and external electromagnetic fields plays a central role in numerous technological applications, Molokov et al 1 Some of the numerous examples include electromagnetic mixing of glass melt (Gopalakrishnan et al 2 ), electromagnetic braking in continuous casting of steel (Cukierski and Thomas 3 ), new generation of flow meters (Vire et al, 4 Kirpo et al 5 ), etc. In great number of industrial applications where the electrically conductive fluids are used (e.g., crystal growth, heat exchangers, latest generation of fusion reactors), heat transfer plays a central role.…”

Chaotic Advection for Thermal Mixing

“…This solution was envisaged in the context of glass melt by Gopalakrishnan et al (2010). However, there is another way to heat the uid: volumetric Ohmic heating.…”