Transient solutal convection in a rectangular enclosure

An electrochemical system based on a diffusion controlled electrolytic reaction is used to study transient solntal convection of a high Schmidt number fluid in a cavity. The electrolyte used is cupric sulfuric acid. Using the heat and mass transfer analogy, the current solntal convection of high Schmidt number liuid results can be used to simulate thermal convection of high Prandtl number fluid. The development of flow structure with time is very complex and is some what different from the results found in the thermal experiments. Secondary cells near the solntal boundary layer and vortices induced in the corners are observed. At certain stage, either one of them can induce a circulation cell in the core which is opposed to the boundary-driven flow. The solntal stratification process due to intrusion and accumulation of the solntal boundary layer flows is studied. Layer interfaces between the core and the stratified layers are observed. A mathematical model used to predict the nondimensional layer interface motion is developed and the results are compared with the data. Both data and prediction indicate that the layer growth rate increases slightly with increasing the solntal Rayleigh number. This is due to the fact that some portion of the outer viscous layer in the bulk can be advected and diffused into the stratified layer.