A Study on Mixing Mechanism of a Stably Stratified Solution between the Heated and Cooled Vertical Parallel Plates

Measurement of Concentration and Temperature Profiles formed by Double Diffusive Natural Convection Using Optical Fiber Sensor

Abstract

In this report an experimental study of double diffusive natural convection is performed for a sucrose solution between vertical parallel plates which is heated from one side and cooled from opposite side with an initial condition of a vertically linear concentration gradient. An optical fiber sensor with a thermocouple is used to obtain the vertical distributions of concentration and temperature. The number of multi-layered convection cells changing with the elapsed time from the start of cooling and heating can be counted and the thickness of cells are measured precisely. It is shown that the evolution of layering is a typical example of self-organization in non equilibrium systems. The relationship between the lifetime which is the elapsed time required to become to a vertically uniform concentration and Rayleigh number is obtained. The observation by shadowgraph is also conducted as an auxiliary method.