NATURAL CONVECTION IN A SQUARE ENCLOSURE HEATED PERIODICALLY FROM PART OF THE BOTTOM WALL

Abstract

Transient heat transfer by laminar natural convection in a square cavity partially heated from below is studied numerically using a finite difference procedure. The temperature of the heating element is uniform, but its magnitude varies sinusoidally with time, oscillating about a fixed mean value. The opposite cold wall is maintained at a constant temperature, while the rest of the bottom wall and the vertical walls are adiabatic. The transient solutions obtained are all periodic in time (0.02 ≤ τ ≤ ∞). Parameters of the problem are the enclosure aspect ratio (A = 1), dimensionless length of the heating element (0.125 ≤ B ≤ 0.5), position of the heating element (0 ≤ a ≤ 0.25), dimensionless amplitude of the heating element temperature (0 ≤ a ≤ 0.4), Prandtl number (Pr = 0.72), and Raykigh number (10 5 ≤ Ra ≤ 2 × 106). Heat transfer and effects of various parameters on the flow and temperature fields are studied.