Abstract:

In this numerical study, the effects of the initial y plus, which is a dimensionless wall distance, on the results of aerodynamic coefficients of designed a wing using NACA 4412 airfoil are investigated. For this purpose, the wing is designed and external flow analysis is carried out according to constant altitude. ANSYS Fluent, which is a Computational Fluid Dynamics (i.e. CFD) program and solves the problems according to the Finite Volume Method (i.e. FVM), is used for external flow analysis. Pressure-based method is used for numerical studies. Thus, the differences of coefficients on the wall, which are the results of the change in the initial y plus, are calculated ideally. Because of one of the best methods to solve the problems on transition zone, γ-Reθ SST turbulence model is used for this study. Using this model for each analysis, first element heights (i.e. the distance to the nearest wall) are calculated according to 9 different y plus (i.e. 1, 5, 10, 30, 45, 60, 75, 90, 105). According to the first element heights, the inflation layers are created on the wing and the 3D control volumes are formed along the boundary region. To be more comprehensible, orthogonal quality-skewness values, expressing the quality of control volumes, are presented for each boundary. The changes in lift coefficients and drag coefficients on the same wing according to these 9 different y plus are presented numerically. In addition, obtained results are evaluated and as described in the literature, it is observed that to calculate the aerodynamic forces with the γ-Reθ SST turbulence model is directly proportional to the initial y plus. As a consequence, this paper demonstrates that there are obvious differences detection of separation and determination of reattach region of flow occurring on the wing according to the initial y plus.