A source of ideas and information for scientists whose work involves understanding and modelling turbulent flows with free surfaces. It has the following merits: (1) it provides a framework for developing the analysis of this field, which, although important, has received only limited study; (2) it recognizes the importance of the two-phase nature of strongly disturbed free surface flows, with both natural and technological applications; (3) it suggests possible lines of future research (especially experimental) to quantify the characteristics of flow regimes which are mainly known qualitatively at present
