Abstract: Numerical simulation of windbreak effect on airflow characteristics over a single smooth curved hill is carried out by setting up a solid windbreak fence of different heights and locations upstream of the hill crest. The steady, compressible, Euler equations are used to simulate the subsonic, incompressible flow over topography such as two-dimensional isolated curved hill with and without windbreak fence. The main computational scheme is an explicit, McCormack finite difference predictor-corrector scheme with two possible combinations denoted as Forward-Backward (F-B) and Backward-Forward (B-F) in a cyclic manner to eliminate any source of error accumulation caused by the directional dependence. The scheme required an artificial dissipation to damp out and avoid any unphysical oscillation in the vicinity of strong gradient. The 2-D computational domain with nonuniform Cartesian grid system extends from Lx = 30h in the streamwise x-direction to Ly = 6h in the normal y-direction, where h is the hill's height. The study focused on a flow over 2-D smoothly curved hill, mounted on a flat plate. A windbreak passive control mechanism was simulated using a vertical fence with one grid space thickness, in the windward upstream of the hill. The fence was established at distance, varied from 4h to 10h upstream of the hill crest. Four fences with different heights; 0.1875h to 1.5h, are used. The wind speed varied from 4.25 to 17 m/s, which corresponding to 0.0125 to 0.05 Mach number, respectively. The velocity vectors, streamlines, and Mach contours patterns as well as the velocity distribution at different x-locations with and without fences over a series of wind speeds are calculated and plotted over the whole domain. For a single-hill configuration, no recirculation zone exists behind the hill. However, in the presence of a single fence with moderate height upstream of the hill, a recirculation zone may takes place between the fence and the hill. The strength, size and shape of the generated recirculation are strongly dependent on flow speed and fences heights and location. The results investigated that the presence of windbreak fence shifted the velocity profile upstream of the hill crest and enhanced the inverse drag and flow separation. The heights of the fences affect the size and extent of the recirculation wake zones. In general, the taller the fences, the longer the wakes. The space between the fence and the hill determines whether the hill will be within the recirculation wake of the upwind fence or not. Placing a high-rise fence in an area of low-rise hill may create a strong air flow at ground level that causes airflow in the upwind hill to reverse direction.