Introduction to air-water flows

Abstract

For many hydraulic structures, safe operation can only be achieved if not only the characteristics of the water flow are considered, but due attention is also given to the simultaneous movement of air in the system. Although the difference in specific weight of air and water is so large that they are usually well separated by a sharp interface, a number of flow configurations lead to an intensive mixing across this surface. This process is called air entrainment. Consideration of the effects of entrained air upon water flow may be essential to provide for the safe operation of a hydraulic structure.