Magnetic control of convection and thermal gradients in liquid gallium with internal heat generation

This study numerically investigates the behavior of natural convection in a cavity filled with liquid gallium using the lattice Boltzmann method with a Multiple-Relaxation-Time scheme. The novelty of this work lies in its analysis of the interplay between buoyancy forces, induced by both internal heat generation and external heating, and the damping effects of an applied magnetic field via Lorentz forces. This study aims to understand their combined impact on flow patterns and heat transfer characteristics within a liquid metal domain, offering new insights into thermomagnetic convection. The findings provide valuable insights for optimizing thermal management in systems utilizing liquid metals. In electronic cooling devices, for instance, gallium and similar alloys can enable efficient heat dissipation. In contrast to the magnetic field's damping effect, internal heat generation enhances flow circulation and can induce an oscillatory regime. An exploration of various parameters, including internal heat generation, heater location, magnetic field intensity, and orientation, revealed that magnetic fields aligned at 0° and 90° suppress flow more effectively than those at 45° or 135°. For specific combinations of internal heat generation and magnetic field strength, the flow exhibits periodic oscillations, which grow more complex as the magnetic field intensifies. Phase-plane analysis shows these oscillations evolving from a nearly sinusoidal pattern at Ha = 0 to intricate, nonlinear paths under an applied magnetic field, highlighting the competition between magnetic damping and thermal buoyancy. Furthermore, positioning the external heater at the bottom maximizes flow circulation, while a top location results in the most pronounced heat dissipation along the upper region of the cold wall.