This study applied a passive flow control technique using split variations to enhance the aerodynamic performance of the NACA 0015 airfoil. While previous research has focused on the benefits of splits, this investigation examines specifically the effects of different splits’ slope configurations on airfoil efficiency. A deeper understanding of varying split configurations as a flow control method can be achieved through this. The research used a computational fluid dynamics (CFD) approach using the k-ε turbulence model, as it applies to fully turbulent flows and can be used to solve for the airflow around complex geometries. This research simulated three splits, each with a different slope configuration measuring from the trailing edge. The results revealed that while the split variations did not increase lift, they effectively reduced drag, improving overall efficiency. The split with a 450 × 400 slope showed the highest performance. These findings are further validated by pressure and velocity contour analyses.