Numerical Analysis of Aerodynamic Sensitivity to Localized Surface Roughness on a NACA 2412 Airfoil

This study evaluates the aerodynamic impact of localized surface roughness on a NACA 2412 airfoil at a 4° angle of attack using CFD simulations with the k-omega SST turbulence model. Surface contamination was modeled using Nikuradse's equivalent sand-grain height across ten discrete chordwise segments. Results quantify variations in the drag coefficient (Cd), revealing that the most significant drag increases occur near the leading edge (0.0c-0.3c). In this region, the boundary layer is thin, allowing roughness elements to interact more strongly with the flow and substantially increase skin-friction drag. The findings conclude that maintaining surface cleanliness in the forward portion of the airfoil is critical for preserving aerodynamic efficiency.