Vortex Shedding behind an Airfoil: Where the Particles Come From

Intensifying interest in flow actuation during flight is driving the quest of understanding vortex shedding flow structure. In support of this goal, fundamental questions regarding particle behavior must be answered. One such question is where the particles that make up a shed vortex pair come from, and how do they form into the recognizable shape now well known to fluid dynamisits. To answer this question, the distinctive regions of particle mixing which make up the vortex shape have been identified and advected backwards in time to understand how a vortex forms.