LAYER GROWTH-PROCESS OF TRANSIENT THERMOSOLUTAL CONVECTION IN A SQUARE ENCLOSURE

The rate of layer growth during thermosolutal convection in a square enclosure is studied both experimentally and analytically. The thermosolutal convection is induced by the combined thermal and solutal buoyancies which either augment or oppose each other. The layer growth process is attributable to the vertical solutal boundary flow which accumulates and stratifies along the horizontal wall. A mathematical model, based on the filling box process used to predict the layer growth rate, is developed. The solutal boundary flow that enters or exits the stratified layer is calculated by using an integral solution for natural convection due to combined thermal and solutal buoyancies along a vertical plate. Comparison of layer growth rate between the prediction and the data is made, and the agreement is excellent if the actual thickness of the solutal boundary layer flow at the inlet and the outlet of the stratified layer can be accurately determined. The actual thickness of the solutal boundary layer flow at the inlet and the outlet is found to increase with increasing buoyancy ratio.