Experimental investigation on magneto-convective flows around two differentially heated horizontal cylinders

Abstract

Liquid metal buoyant flow around two differentially heated horizontal cylinders in the presence of a uniform vertical magnetic field is investigated experimentally. While magneto-convection in pipes or ducts has been studied theoretically and experimentally in recent years, data for heat transfer at immersed obstacles are rare and, to our knowledge, detailed experimental investigations on this fundamental magnetohydrodynamic problem do not exist. In the present work, two horizontal cylinders inserted into an adiabatic rectangular cavity filled with gallium–indium–tin are kept at constant temperatures to establish a driving temperature gradient in the surrounding liquid metal. The buoyancy-driven flow, quantified by the Grashof number $Gr$ , is varied in the range ${10^{6} \leq Gr \leq ~5\times 10^{7}}$ . With increasing magnetic field, expressed via the Hartmann number $Ha$ , different flow regimes are identified from measurements for $0 \leq Ha \leq ~3000$ . The effect of the electromagnetic force primarily consists in suppressing turbulence and damping the convective flow. The heat transfer is quantified in terms of the non-dimensional Nusselt number $Nu$ , and its dependence on $Gr/{Ha}^{2}$ , which is identified as the important group governing the flow, is discussed.