Computations of steady and unsteady low-speed turbulent separated flows

Numerical computations are presented for two-dimensional steady and unstead y separated flows. The first case is a low-speed, converging-diverging duct with a rapid expansion, creating a large separated flow region. The second case is the Massachusetts Institute of Technology flapping foil experiment , where a stationary hydrofoil Is subject to gust loading. Numerical soluti ons are obtained by solving the incompressible Navier-Stokes equations. The se equations are solved in a time accurate manner using the method of artif icial compressibility. The Johnson and King (Johnson, D, A., and King, L. S ., "A Mathematically Simple Turbulence Closure Model for Attached and Separ ated Turbulent Boundary Layers," AIAA Journal, Vol. 23, No. 11, 1985, pp, 1 684-1692) turbulence model is employed for modeling the turbulent dow Modif ications to the model are suggested that take into account the normal stres s production of energy and the strong adverse pressure gradient associated with separating hows, The performance of the Johnson and King model and its modifications are studied for both steady and unsteady Bow conditions. The numerical solutions are compared to experimental data.