NATURAL-CONVECTION IN A SQUARE ENCLOSURE PERIODICALLY HEATED FROM BELOW - NUMERICAL STUDY

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 tau). Parameters of the problem are the enclosure aspect ratio (A = 1), dimensionless amplitude of the heating element temperature (0 a 0,8), the Prandtl number (Pr = 0,72) and the Rayleigh number (10(5) Ra 10(6)). Heat transfer and effects of various parameters on the flow and temperature fields are studied.