Visualisation of Air Entrainment by a Plunging Jet

The phenomenon of air entrainment by water jet plunging on the free surface of a water pool is reported in the paper. An effort has been made to understand the physics of the phenomenon through elaborate visual and photographic observations. The formation of air sheath, the downward motion of the two phase jet, the reversal of the jet motion has been reported. The visualisation of the random motion of a single bubble has also been reported.