ANALYSIS OF LOW-REYNOLDS-NUMBER AIRFOIL FLOWS

Compressible steady and unsteady flowfields over a NACA 0012 airfoil at transitional Reynolds numbers are investigated. Comparisons with recently obtained experimental data are used to evaluate the ability of a numerical solution based on the compressible thin layer Navier-Stokes approximation, augmented with a transition model, to simulate transitional flow features, The discretization is obtained with an upwind-biased, factorized, iterative scheme. Transition onset is estimated using an empirical criterion based on the computed mean flow boundary-layer quantities. The transition length is computed from an empirical formula. The incorporation of transition modeling enables the prediction of the experimentally observed leading-edge separation bubbles. Results for steady airfoil flows at fixed angles of attack and for oscillating airfoils are presented.