A Comparative Analysis of Turbulence Models in FLUENT for High-Lift Airfoils at Low Reynolds Number

Abstract

At a low Reynolds number, the aerodynamic properties of an airfoil are highly influenced by the viscous shear flow near the wall-bounded region. The flow undergoes a transition from laminar to turbulent forming a laminar separation bubble (LSB). Therefore, to accurately simulate the viscous flows, shear stresses in the boundary layer need to be carefully evaluated. The aim of this research is to identify a turbulence model which can accurately compute aerodynamic force coefficients for high-lift airfoils using Finite Volume Method in a commercially available software - Ansys FLUENT. We analyzed three different turbulence models: Spalart Allmaras (SA), SST k-ω (γ), and k-k <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</inf> -ω at a low chord-based Reynolds number for two high-lift airfoils, E423 and S1223. The computation results are compared with results generated by XFoil, which solves viscous flows using panel method and boundary layer theory, and experimental data. The results show that SST k-ω(γ) model generates at least 8.6% better results in predicting coefficient of drag as compared to other turbulence models, and SA model outperforms SST k-ω(γ) in predicting lift coefficient taking into account the computational cost.