Air entrainment is not a singular event but a multi-stage process driven by the instability of the air-water interface:
Air Bubble Entrainment in Free-Surface Turbulent Shear Flows Air Bubble Entrainment in Free-Surface Turbulen...
A surface cavity develops, reaching deeper into the water while the sides remain smooth. Air entrainment is not a singular event but
"Air Bubble Entrainment in Free-Surface Turbulent Shear Flows" is a seminal area of study in hydraulic and fluid engineering, primarily defined by the work of Hubert Chanson . This process occurs when turbulence in a liquid becomes strong enough to overcome surface tension and gravity, causing air to be trapped and dispersed as bubbles into the flow. Core Mechanisms of Entrainment Core Mechanisms of Entrainment The free surfaces enclose,
The free surfaces enclose, releasing a single or group of air bubbles into the turbulent flow. Key Drivers and Models
The free surface begins to deform slightly, but no air is yet trapped.
The cavity collapses due to local instabilities, often following a power-law scaling.