An analytical and numerical study for geometrical optimizing of a solar chimney prototype at University of Tehran was performed. A fundamental mathematical model that describes the flow was presented, and the performance evaluation of solar chimney was simulated with operational and geometric configurations. The numerical predictions were validated through comparison with the experimental data of the solar chimney pilot which was constructed in height of 2 m and collector radius of 3 m. The results show that, the collector inlet of 6 cm, the chimney height of 3 m, and the chimney diameter of 10 cm were the best alternatives for the constructed solar chimney pilot. It is found that the velocity magnitude can be raised to 4-25% in different cases; also the analysis indicated that the height and diameter of the chimney are the most important physical variables for solar chimney design. (C) 2014 Elsevier Ltd. All rights reserved.