10. Simulation of Laminar-To-Turbulent Transitional Flow Over Airfoils

In this work, the simulation of an airfoil with NACA 63-618 cross section was performed to obtain the curves of the lift and drag coefficients as a function of the angle of attack. The interest in this profile is its application in operational current turbines, such as SeaGen, which can harness the kinetic energy of the currents of rivers and seas. A two-dimensional model was used to simulate the airfoil with a chord of 0.23 m. The Reynolds number was Re = 5.3 × 10⁵ and the angle of attack varied between −5° < α < 15°. The values obtained were compared with experimental tests and other simulations. Several conventional RANS turbulence models have been applied, such as k-ε, optimized k-ε, SST and RSM, however none of them presented results that were in accordance with the literature. The Transition SST model showed better agreement with the experiments. It was demonstrated in the present study that the Transition SST model is fundamental in this specific case. This happens because there is a laminar-turbulent transition on the airfoil. Therefore, computational fluid dynamics (CFD) models accurately simulate provided appropriate numerical techniques are employed.