This book develops an analysis of the air entrainment processes in free-surface flows. These flows are investigated as homogeneous mixtures with variable density. Several types of air-water free-surface flows are studied: plunging jet flows, open channel flows, and turbulent water jets discharging into air. Experimental observations reported by the author confirm the concept that the air-water mixture behaves as a homogeneous compressible fluid in each case. This book will be of great interest to professionals working in many fields of engineering: chemical, civil, environmental, mechanical, mining, metallurgy, and nuclear.Key Features* Covers new information on the air-water flow field: air bubble distributions, air-water velocity profiles, air bubble sizes and bubble-turbulence interactions* Features new analysis is developed for each flow configuration and compared successfully with model and prototype data* Includes over 372 references and more than 170 figures with over 60 photographs* Presents useful information for design engineers and research-and-development scientists who require a better understanding of the fluid mechanics of air-water flows