Properly designed upstream-traveling suction/blowing waves could reduce drag.

Theoretical and computational research has yielded some advances in the art of designing active feedforward and feedback controllers to suppress thermal convection and reduce drag (by suppressing turbulence) in boundary-layer flows. The advances include (1) improved means for designing reduced-order (and, hence, computationally more efficient) controllers and (2) discovery of a previously unknown phenomenon that could be exploited for feedforward control to reduce drag.

Flow in a Channel bounded by flat upper and lower walls would be modified by blowing/suction actuators on the walls. The actuators would be excited in accordance with open-loop and/or closed-loop control laws.