Low Prandtl number convection in layers heated from below

Abstract

Experimental results are presented for the heat transfer across a horizontal layer of liquid sodium heated from below. The experiments show that up to a Rayleigh number of Ra ~ 7000 heat is mainly transferred by conduction for this low Prandtl number fluid. Beyond this threshold value the heat transport by convection increases significantly. For higher values of the Rayleigh number the measured Nusselt numbers follow a power law Nu ~ Ra 0.2 which is slightly smaller than the one predicted for the so-called flywheel convection as suggested by Jones et al. [ J. Fluid Mech. 73, 353–388 (1976)].