Experimental investigation has been carried out on natural convection induced around heated horizontal square cylinders. Main concerns were the influence of inclination angle on the flow and heat transfer characteristics. The inclination angles from horizontal θ and the side lengths d were varied systematically as θ = 0, 15, 30, 45° and d = 10, 20, 30, 50 mm. The experiments were performed in the range of modified Raleigh numbers, Ra_d^*, from 2×10^5 to 1×10^9. The flows around the square cylinder and the surface temperatures were visualized with dye and liquid crystal thermometry, respectively. The result shows that the onset of three-dimensional separation is delayed with increasing the inclination angle. The local heat transfer coefficients were also measured. The results showed that the heat transfer of square cylinder is enhanced with increasing the inclination angle.
