Performance Assessment of Some Popular RANS Models by Relevance to High-Lift Aerodynamics

Abstract

Comparative assessment of some most widely used RANS models ranging form eddy-viscosity type transport models (EVM), including also an elliptic-relaxation-method-based model version, to second-moment closures (SMC) utilizing the solutions of the equations governing the Reynolds stress tensor has been performed on the basis of selected flow configurations relevant to high-lift aerodynamics. A hybrid EVM/SMC model combining the advantages of both model groups with respect to numerical robustness pertinent to the EVM concept and the physical accuracy of the SMC schemes is also part of the present study. All models are the near-wall formulations. In addition, some model formulations were applied in conjunction with the universal wall boundary conditions combining the exact conditions and standard wall functions depending on the position of the wall-closest computational node. The computations were performed by using three codes, all based on the Finite Volume method, the DLR FLOWer code, the AVL FIRE code and the in-house code FUN-2D. The considered wall-bounded flow configurations affected by adverse pressure gradient causing weak and massive separation include a plane asymmetric diffuser and three high-lift airfoils: Aerospatiale A-airfoil, three-element airfoil and NACA 4412 airfoil (two angles of incidence: 13.87 deg. and 15 deg. were considered). The model results are analyzed and discussed in conjunctions with available experimental database.