A large eddy simulation of an airfoil turbulent wake subjected to streamwise curvature

Abstract

This paper presents large eddy simulations (LES) of the curved wake of an airfoil. The wake was generated by placing a NACA0012 airfoil in a uniform stream of air, which is then subjected to an abrupt 90° curvature created by a duct bend. The trailing edge of the airfoil is one chord length upstream of the bend entry. The duct cross-section measures 457 mm × 457 mm, and the bend has radius to height ratio of 1.17. The flow Reynolds number (1.02 × 105) is based on a mainstream velocity of 10 m/s and airfoil chord length 0.15 m. The sub-grid scale models employed are the classical Smagorinsky, its dynamic variant and the dynamic kinetic energy transport. The performance of LES in depicting the experimental flow is assessed and compared with results predicted by the Reynolds stress model (RSM). The results show the advantages of LES over Reynolds-averaged Navier-Stokes methods in predicting convex wall separation in strongly curved ducts on relatively coarse grids. Results from LES on a considerably finer near-wall-resolved grid lead to much improved comparison with the experimental data in the near wake, bettering predictions by RSM and LES on the coarse grid. Copyright © 2008 John Wiley & Sons, Ltd.