Experimental Studies of Free Convection in a Rectangular Cavity

Abstract

Experimental studies on thermal convection flow of water between two vertical parallel plates held at different temperatures were carried out. The flow pattern between the plates and the type of distributions of the velocity and the temperature depend almost only on the Rayleigh number A . ( A =γ Δ T g d 3 /(κν), Δ T being the temperature difference, d the distance between the plates, γ the thermal expansion coefficient, κ the thermal diffusivity, ν the kinematic viscosity, and g the acceleration of gravity.) As the Rayleigh number becomes larger, the flow tends to the type of boundary layer flow. There has been found a critical value of the Rayleigh number, such that, below it the flow is always laminar and above it the flow becomes unstable. Beyond the critical value (\(A_{\text{crit.}}{\fallingdotseq}12{\times}10^{6}\)) wavy motions of streamlines appear, then they develop to rows of periodic vortices and eventually burst into turbulent flow.