Natural convection in an inclined square cavity in regions of density inversion of water

Abstract

The steady laminar natural convection of water in an inclined square cavity is investigated experimentally and analytically at temperatures in the neighbourhood of maximum density near 4°C. One hot wall of the square cavity is maintained at various uniform temperatures from 2 to 20°C and the opposing cold wall is kept at a uniform temperature of 0°C, while the other walls are thermally insulated. Photographs and analytical descriptions of the flow patterns, temperature profiles in the water layer and average heat-transfer coefficients are presented in this paper for various surface temperatures Th of the hot wall and inclination angles of the square cavity θ from 0° (heated from below) to 180° (heated from above) by 30° intervals. From this study it should be noted that the density inversion of water has a strong effect on the natural convection occurring in the inclined square cavity, and the average heat-transfer coefficient is a peculiar function of the surface temperature of the hot wall, unlike previous results for Boussinesq fluids without density inversion. Solutions of the governing equations for steady two-dimensional laminar natural convection are obtained numerically, and the results obtained agree reasonably well with the experimental ones in the ranges of 30° < θ ≤ 180° for Th > 8°C, 0° ≤ θ ≤ 120° for Th < 8°C, and 0° ≤ θ ≤ 180° for Th = 8°C.