Numerical analysis of double-diffusive convection in a two layer system bylateral heating and cooling

Double-diffusive convection in a solutally stratified, two-layered solution destabilized by lateral heating and cooling is studied numerically. A simu lation was carried out for Pr = 6.67, Le = 184, Ra-T = 2.43 x 10(7), Ra-c = 3.13 x 10(7) and A = 1.1. Experiments were also performed with aqueous sol utions under the same condition. Time evolutions of flow and temperature fi elds obtained numerically show qualitative agreement with that obtained by the visualization of flow and temperature. Moreover, numerical results of t he molar flux of solvent through the interface agree very closely with expe rimental ones. Thus the numerical algorithm employed here is proved to be a ppropriate for the analysis of double-diffusive convection. Using the numer ical results, the mechanism of mass transfer, which is usually hard to inve stigate through experiments, is discussed. The double-diffusion process unt il the two layers start mixing can be divided into three periods; (A) a per iod until a thin interface is formed between the two layers, (B) a period d uring which the temperature field is in quasi-steady state, and (C) a perio d when the interface between the two layers is unstable. Numerical results show that each period has different mechanism of mass transfer.