An Experimental Study of the Thermal Convection in a Vertical Torus

Abstract

An experimental study was made on the thermal convection in a thin vertical torus placed in a nearly uniform negative vertical temperature gradient. We analysed the flow field by several visualisation methods as well as an LDV (laser Doppler velocimeter) measurement. The critical Rayleigh number, the Rayleigh number dependence of the velocity profile of a quasi-one-dimensional flow along the loop, and the three-dimensional flows with cellular structures before the system became chaotic are shown. The existence of the cellular structures is quite different from the behaviour expected by the Lorenz model.