A numerical investigation is made of buoyant convection of a paramagnetic fluid in a cubical enclosure under constant gravity go. Conventional buoyant convection arises by maintaining different temperatures at two opposite vertical sidewalls. The other walls are thermally insulated. To this basic layout, an electric wire is placed below the bottom horizontal wall to produce a magnetic field. The magnetizing force is induced, which modifies the convective flow and heat transfer characteristics. Comprehensive numerical solutions have been acquired to the governing equations. Of interest are the cases when the strength of the magnetizing force is time-periodic. The computed results reveal the presence of resonance, which is characterized by maximal amplification of the fluctuations of heat transport in the interior. The flow is shown to resonate to the basic mode of internal gravity oscillations. The study points to the feasibility of using the time-periodic magnetizing force as an effective regulator of the convective fluid system. (C) 2004 Elsevier Ltd. All rights reserved.