Convection Near the Temperature of Maximum Density for High Rayleigh Number, Low Aspect Ratio, Rectangular Cavities

Abstract

Natural convection in rectangular cavities with the vertical endwalls differentially heated about the temperature of maximum density of water was studied in the laboratory. In order to control heat losses, the experiments were conducted in a large cold room with the air temperature maintained at 4°C. The Rayleigh number was varied over the range 105 to 108 and the aspect ratio over the range 0.1 to 0.5. The flow field consisted of a double cellular circulation, and the observed temperature field, flow field, and heat transfer rates were compared with analytical predictions in the diffusive regime. The experiments demonstrated that the interior sinking flow was unstable for Ra > 107.