Viscous and Inertial Convection at Low Prandtl Number: Experimental Study

Rayleigh-Bénard convection in mercury is studied in the vicinity of its threshold with a high-resolution experimental system. The Prandtl number of the fluid is varied between 0.02 and 0.04. The experimental evidence of two different stationary convective regimes, called viscous and inertial, is reported. Their dependence on the Prandtl number P is compared with the theoretical predictions in the small Prandtl-number limit.