NATURAL-CONVECTION IN A 2-DIMENSIONAL SQUARE LOOP

The present investigation deals with the steady-state natural convective flow inside a two-dimensional square loop. Opposite legs of the loop are held at constant but different temperatures and therefore, due to the presence of gravity, fluid motion ensues; viscous effects resist the motion and a steady-state flow is reached. The geometry of the loop is fixed but several temperature differences have been considered. Also, the effect of the tilt angle on the flow patterns has been analyzed. Local recirculating motions are the dominant features of the flow when the upper walls are at higher temperature than the lower ones. In contrast, a single global cell appears when the loop is tilted. Double solutions have been found for tilt angles close to zero (high temperature at the bottom walls); the size of the tilt angle interval where double solutions exist has been determined as a function of the Rayleigh number. One-dimensional models have predicted multiple steady-state solutions in systems similar to the one studied here; in the present paper, the existence of multiple solutions in a two-dimensional model has been demonstrated. © 1990.