Numerical Study of Separated Turbulent Flow over Airfoils

A numerical scheme for the solution of two-dimensional time-dependent Reynolds equations is developed and applied to the flow past airfoils. The airfoil is mapped conformally into a circular cylinder, and the equations are solved in the cylinder plane. The turbulence models used in this study are the mixing-length model and a hybrid model consisting of mixing-length model and the two-equation k-€ model. An explicit integral relation is used to determine the kinematics of the problem. After the method was calibrated using simpler geometries, it was applied to the case of a 12% thick Joukowski airfoil at 15 deg angle of attack, at a Reynolds number of 3.6 X10. It is observed from the results that the turbulent flow past an airfoil at high angles of attack shows oscillatory behavior (with the lift and drag coefficients continuously varying with time) similar to the behavior in laminar flows.