The present study presents the computational modeling of transitional flow over NACA-0018 airfoil at low chord Reynolds number of 105 at various angles of attack ranging from 0o to 15o using two-dimensional Reynolds-averaged Navier-Stokes equations (RANS) combined with the Menter’s (γ-〖R ̃e〗_θ) transition model. Two different computational domain configurations were optimized in order to investigate the effect of the wind tunnel walls on the developed flow. The structured mesh technique was used for both domains in order to generate high-quality grids that obtain the turbulence model requirements. The numerically predicted results of the airfoil aerodynamic forces presented in terms of lift and drag coefficients as well as boundary layer predictions including surface pressure distribution, skin friction coefficient, mean velocity profiles, RMS velocity profiles, and the boundary layer displacement thickness were compared to the experimental data. Very good agreement was attained prior to the airfoil stall angle, whereas the agreement became poorer as the airfoil was completely stalled.