An inverse method of heat transfer estimation from cylinder is developed. Levenberg-Marquardt method has been coupled with Duhamel’s theorem. Experiments were conducted for 1.1 × 104 ⩽ Re ⩽ 6.2 × 104 in wind tunnel. Local and average Nu correlations are developed for 1.1 × 104 ⩽ Re ⩽ 6.2 × 104.