Abstract
Experimental investigation has been carried out on natural convection of air induced around heated horizontal square cylinders. Main concerns were the flow and heat transfer characteristics of high Rayleigh number flows. The experiments were performed in the range of modified Raleigh numbers, Ra_d, from 10^5 to 4 × 10^9. The flows around the square cylinder were visualized with smoke. The result shows that the ascending flows along vertical side surface begin to separate three-dimensionally from the upper surface of the square cylinder when Ra_d* = 2 × 10^6. The local heat transfer coefficients were also measured. The results showed that the coefficients of the upper surface are increased, in particular, with the occurrence of the three-dimensional separation
