Various flow regimes and their correlation with the vortex shedding are investigated numerically using the γ − Reθt transition turbulence model over a hydrofoil. The purpose is obtaining a numerical model able to accurately simulate the vortex shedding. The study is done on a 2D NACA0009 hydrofoil with two configurations. First configuration has fully smooth surfaces, and the second one has two rough layers of sand grain added near the leading edge of the hydrofoil. The presented are in good agreement with experimental data from the literature. The added roughness is forcing an early transition around 0.08 of the total chord length compared to the smooth surface at 0.8. Furthermore, the boundary layer thickness increases which leads to a reduced frequency and amplitude of the von Karman vortices.