Blow-up and control of marginally separated boundary layers

Abstract

Interactive solutions for steady two-dimensional laminar marginally separated boundary layers are known to exist up to a critical value Γ c of the controlling parameter (e.g. the angle of attack of a slender airfoil) Γ only. Here, we investigate three-dimensional unsteady perturbations of such boundary layers, assuming that the basic flow is almost critical, i.e. in the limit Γ c − Γ →0. It is then shown that the interactive equations governing such perturbations simplify significantly, allowing, among others, a systematic study of the blow-up phenomenon observed in earlier investigations and the optimization of devices used in boundary‐layer control.