Abstract: A method and device utilizes boundary layer separation control for the purpose of wake vortex alleviation. Trailing vortices are manipulated by varying the spanwise vortex-sheet strength via either passive or active boundary layer separation control. Boundary layer separation can be diminished or promoted to vary vortex properties, such as locations and strengths, so as to generate wake signatures that are unstable, resulting in complex three-dimensional interaction and rapid destruction of vortex coherence in the wake. Separation control can be achieved in either a time-dependent or a time-invariant mode.