“…Most of the initial work on plunging jets in the continuous entrainment regime, as documented in Cummings and Chanson (1997a and b), Evans et al (1996), McKeogh and Ervine (1981), Schmidtke et al (2009), Sene (1988) and Van de Sande and Smith (1976), was experimental and semiempirical in nature, aimed at understanding the conditions of inception, the various mechanisms of air entrainment and the development of correlations to predict the penetration depth of the bubbly plume and the rate of gas entrainment. Works aimed at understanding the topological development of the flow during the initial phase of impacting jets by way of air cavity sizes, shapes, air entrainment rates and their scaling laws include notably those of Oguz et al (1995), Ohl et al (2000), Soh et al (2005) and Zhu et al (2000). Subsequent to the initial phase of impact, Kiger and Duncan (2012) and McKeogh and Ervine (1981), in their reviews, discuss two main air entrainment mechanisms-(i) air entrainment for weakly disturbed plunging jets characterized by a smooth surface and (ii) air entrainment for highly disturbed jets where the jet stream is non-uniform and its surface possesses regular or irregular ripples of varying sizes depending on the jet developing length.…”