Experimental study of double-diffusive convection in a rotating annulus with lateral heating

Experimental investigations are made to study the double-diffusive convection phenomena of a stably-stratified salt-water solution due to lateral heating in a stationary and rotating annulus. The primary objective of this study is to obtain the basic information on the nature of natural convection with time with various parametric conditions such as rotating velocity, temperature and concentration gradients. The experiments cover the ranges of Ar = 2.0, Le = 100, Ra(η) = 1.57 x 10²-3.09 x 10⁵, and Ta = 0-1.20 x 10⁷. In the stationary annulus, four distinct flow regimes are observed depending on the effective Rayleigh number Ra(η): (i) stagnant flow regime, (ii) partially-formed layer flow regime, (iii) fully-formed layer flow regime, and (iv) unicell flow regime. In the rotating annulus, only fully-formed layer flow regime is observed. The temperature profile has usual inverse 'S' shape and the concentration profile is uniform in each layer due to the convective mixing both in the stationary and in the rotating cases. At the interface between adjacent layers, the temperature changes smoothly while the concentration changes rapidly. As the Taylor number (the effect of rotation) increases, the generation of rolls at the hot wall is inhibited and the formation and merging processes of layers are delayed at the given Ra(η).