Electromagnetic vortex suppression to prevent air core phenomenon for draining of electrically conducting liquids

The air core phenomenon observed during liquid suction or drainage through a narrow drain port can be reproduced artificially by starting the draining after rotating the cylindrical tank containing the liquid. Because the entrainment of gas-phase fluids during pump suction or liquid draining generates a breakdown of the machinery or defects in the product, various studies have been conducted to retard or prevent the air core phenomenon. Instead of utilizing an artificial structure such as a mesh or vane, as applied in previous studies, the present study introduces a new approach in which a magnetic field is applied to the container. First, the magnetic field applied induces an electric current through a reciprocal action with the liquid flow in the container. Next, the induced current and applied magnetic field create a Lorentz force, which is an electromagnetic body force. The Lorentz force helps with the suppression of existing flows. To couple the flow and electromagnetic fields, we solve the Poisson's equation for the electric potential along with the momentum conservation. As the draining progresses, a volume-of-fluid (VOF) free surface capturing method is applied to track the free surface evolution, including the air core generation. For various Hartmann number (Ha) conditions, the internal velocities, vorticities, and Lorentz forces are comparatively presented. Finally, the effects of suppressing the air core phenomenon through the application of a magnetic field are discussed.