Suppression of oscillatory convective flow of a liquid metal with a non-uniform magnetic field

In this work, the effect of a non-uniform magnetic field on the convective flow of a liquid metal is experimentally and numerically investigated. A cubic cavity (50 mm length side) filled with GaInSn is subjected to a vertical temperature gradient, inducing time-dependent convection. A permanent magnet in contact with a lateral wall generates a non-uniform magnetic field, with its main component perpendicular to the thermal gradient. This configuration generates a Lorentz force that interacts with the time-dependent flow. The Rayleigh number ranges from 5.9 × 10 4 to 2.2 × 10 5 , while the local Hartmann number at the cavity center is 100. Three-dimensional numerical simulations complement flow velocity profiles measured using the ultrasound Doppler velocimetry technique. Results consistently show that the Lorentz force suppresses oscillatory flow behavior, stabilizing it in a steady-state regime and reducing the heat-transfer rate, as evidenced by smaller average Nusselt numbers. Across the cavity, the maximum Lorentz force decreases by approximately 86% from the wall facing the magnet to the opposite side, highlighting the strongly non-uniform nature of the field, which provides a better approximation of a real magnetic field than a uniform one. • The effect of a non-uniform magnetic field on the convection of a liquid metal is investigated. • 3D simulations complement flow velocity profiles measured using UDV. • The Lorentz force suppresses oscillatory flow behavior. • It reduces the heat-transfer rate, as evidenced by smaller average Nusselt numbers.