Wave breaking produce air-liquid two phase turbulent flows involving large numbers of bubbles. We try to develop a numerical model for the bubbles entrained by breaking waves through in situ and laboratory experiments. Attention is focussed on the size distribution and number density which spatially evolve as a breaking wave front propagates. Visual and acoustic techniques are used in the experiments.
The entrained bubbles involved in the large-scale vortices due to wave breaking typically form the so-called bubble clouds. The bellow video images show formations of the bubble clouds recorded by a submerged video camera in situ observation conducted in 1999.

Ref.
Watanabe, Y., Ohtsuka, J. and Saeki, H., Evolution of bubbly flow in the surf
zone, Ocean Wave Measurement and Analysis (Proc. of 4th intl. symp. WAVES
2001), 992 - 1001 (2001)