The Effects of Initial y plus: Numerical Analysis of 3D NACA 4412 Wing Using $;gamma-Re_theta$ SST Turbulence Model

Abstract

In this numerical study, the effects of the initial y plus, which is a dimensionless wall distance, on the results of aerodynamic coefficientsof designed a wing using NACA 4412 airfoil are investigated. For this purpose, the wing is designed and external flow analysis is carriedout according to constant altitude. ANSYS Fluent, which is a Computational Fluid Dynamics (i.e. CFD) program and solves theproblems according to the Finite Volume Method (i.e. FVM), is used for external flow analysis. Pressure-based method is used fornumerical studies. Thus, the differences of coefficients on the wall, which are the results of the change in the initial y plus, are calculatedideally. Because of one of the best methods to solve the problems on transition zone, $;gamma-Re_theta$ 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 yplus (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 3Dcontrol volumes are formed along the boundary region. To be more comprehensible, orthogonal quality-skewness values, expressingthe quality of control volumes, are presented for each boundary. The changes in lift coefficients and drag coefficients on the same wingaccording to these 9 different y plus are presented numerically. In addition, obtained results are evaluated and as described in theliterature, it is observed that to calculate the aerodynamic forces with the $;gamma-Re_theta$ SST turbulence model is directly proportional to theinitial y plus. As a consequence, this paper demonstrates that there are obvious differences detection of separation and determination ofreattach region of flow occurring on the wing according to the initial y plus.