Experimental investigations of bubble chains in a liquid metal under the influence of a horizontal magnetic field

Abstract

We present an experimental study on bubble chains ascending in the eutectic GaInSn alloy under the influence of a horizontal magnetic field. Argon gas bubbles are injected through a single nozzle positioned in the middle at the bottom of a flat Plexiglas vessel. Bubble size distribution, shape deformation, velocities, etc. are obtained by post-processing of X-ray radiographs measured with a high-speed video-camera for a wide range of Argon gas flow rates. In the case without a magnetic field, the typical zigzag movement of the rising bubbles is observed. This movement and the integrity of the bubble chain are significantly disturbed with increasing gas flow by the turbulent flow in the liquid metal. The main effect of the magnetic field consists in a stabilization of the bubble trajectories. The application of a magnetic field at moderate field strength dampens the turbulent fluctuations in the bubble wake and stabilizes the zigzag movement. The application of a sufficiently strong magnetic field suppresses the zig-zag motion of the bubbles and forces them to follow a straight path. The rising velocity is gradually reduced with increasing magnetic field strength. The motion of the individual bubbles within the chain becomes highly correlated. Ellipsoidal bubbles tend to align their major axes along the magnetic field lines.