Numerical investigation of interactive transition control

Transition control by periodic disturbance superposition is investigated using numerical integration of the three-dimensional time dependent Navier-Stokes equations. Plane Poiseuille flow is treated as a model problem. Both the classical K-type and the subharmonic routes to turbulence are considered. Periodic wall suction and blowing, fluctuating mass forces or direct manipulation of Fourier modes are used alternatively as control inputs. It is found that superposition of purely two-dimensional waves allows an efficient control of transition at an early stage of the transition process but fails once significant three-dimensional disturbances are present. Results obtained with three-dimensional control inputs are also discussed.