Comparison of Numerical Methods Evaluating Airfoil Aerodynamic Characteristics at Low Reynolds Number

The flowfields around the NACA 0012 airfoil at Reynolds numbers 1 x 10(4), 3 x 10(4), and 5 x 10(4) are studied, and the predictability of aerodynamic characteristics derived from various numerical methods is examined. Two-dimensional laminar simulation, two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model, and three-dimensional implicit large-eddy simulation are employed in this study. The two-dimensional laminar and three-dimensional implicit large-eddy simulations accurately predict the separation point, and capture the characteristics of a separation bubble for each Reynolds number and each angle of attack. Nonlinearity in the lift curve is also captured in the results of the two-dimensional laminar and three-dimensional implicit large-eddy simulations. The two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model predicts the separation point nearer the trailing edge than does the two-dimensional laminar and three-dimensional implicit large-eddy simulations, and the separation bubble is not captured for any Reynolds number and angle of attack by this method. Nonlinearity of the lift curve does not appear in the results of the two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model. The two-dimensional laminar simulation can predict airfoil aerodynamic characteristics qualitatively, and it can be used as an appropriate numerical method at lower Reynolds numbers. The three-dimensional-implicit-large-eddy-simulation technique can be employed when more accurate qualitative characteristics are needed.