Comparison of Local Heat Transfer Distribution in Between Three-Dimensional Inclined Closed and Open Cavities

Abstract

The phenomenon of natural convection is investigated in three-dimensional (3D) cavities with four adiabatic walls and one hot wall. The surface opposite to the hot wall is either a wall (closed cavity) at a lower constant temperature or is open to ambient at a lower temperature (open cavity). It is pointed out here that not only overall heat transfer is important, the distribution of local heat transfer is also important. To quantify the uniformity of heat transfer distribution, the ratio of maximum to average heat transfer is calculated for various Rayleigh numbers as well as inclination angles for open and closed cavities. A significant difference in the local heat transfer profile along the hot surface of the closed cavity in comparison to that in open cavity for small inclination angle (especially at higher values of Rayleigh number) is noted. However, the profile is remarkably similar in the case of vertical cavities. For inclined closed cavities, there is a buoyancy component of the flow acceleration normal to the hot and cold wall, which is absent in the case of vertical cavities. For lower inclinations, this component brings the three-dimensionality in the flow field and leads to the differences in the flow patterns. The fluid striking the cold wall in the case of the closed cavity causes significantly different flow patterns that, in turn, lead to nonuniform local heat transfer. To explain the flow behavior, iso-surfaces, stream ribbons, and the Y-components of the flow velocity are plotted at different surfaces of the closed cavity.