Buoyancy-Induced Heat Transfer in Partially Divided Trapezoidal Cavities

Numerical results are reported for natural convection heat transfer in partially divided trapezoidal cavities representing attic spaces. Two boundary conditions are considered. In the first, corresponding to summer-like conditions, the vertical and upper surfaces are heated while the lower surface is cooled. In the second, corresponding to winter-like conditions, the lower surface is heated while the other surfaces are cooled. The effects of Rayleigh number, baffle height, and baffle location on the heat transfer are investigated. Results are displayed in terms of streamlines, isotherms, velocity and temperature profiles, and local and average Nusselt number values. In winter-like conditions, convection starts to dominate at a Rayleigh number much lower than that in summer-like conditions. For both boundary conditions, the presence of baffles decreases heat transfer. For the bottom-cooled case this decrease is greater with a taller baffle, placed closer to the heated walls. For the bottom-heated case the decrease in heat transfer due to the baffles is greater with increasing distance from the vertical wall. Average Nusselt number correlations for both boundary conditions are presented.