Boundary-layer receptivity due to a wall suction and control of Tollmien–Schlichting waves

A numerical study of the generation of Tollmien–Schlichting (TS) waves due to the interaction between a small free‐stream disturbance and a small localized suction strip on an otherwise flat surface has been carried out using finite‐difference methods. The nonlinear steady flow is of the viscous–inviscid interactive (i.e., triple‐deck) type while the unsteady disturbed flow is assumed to be governed by the triple‐deck approximation of the unsteady Navier–Stokes equations linearized about this mean flow. Numerical solutions illustrate the growth or decay of the TS waves generated by the interaction between the free‐stream disturbance and the suction strip, depending on the value of the scaled Strouhal number. An important result of this receptivity problem is the numerical determination of the amplitude of the Tollmien–Schlichting waves and the demonstration of the possible active control of the growth of Tollmien–Schlichting waves.