Calculation of unsteady boundary layers

A relatively simple, yet efficient and accurate finite difference method is developed for the solution of the unsteady boundary layer equations for both laminar and turbulent flows. Using this method calculations of periodic laminar boundary layers are performed for zero and adverse mean pressure gradients, for various oscillation frequencies, for small and large amplitudes, and even in the presence of significant flow reversal. The results are compared with exact analytical solutions, asymptotic solutions and experimental data. The numerical method is then applied to predict an experimental periodic turbulent boundary layer, using simple quasi-steady closure models. The present numerical results are shown to be in better agreement with the measurements than others obtained using identical turbulence models but a different numerical procedure.