  Shear layer instability at the free surface of a water jet is studied. The
accompanying video shows experimental data recorded using measurement methods
such as Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocity
(PIV). These results reveal the mechanisms leading to the formation of
capillary waves on the surface due to the roll-up of the shear layer. These
capillary waves eventually collide to each other, injecting vorticity in the
bulk of the flow. Shear layer and injected vorticity interact to form a counter
rotating vortex pair that moves down to the flow.
