ABSTRACT
This chapter discusses the equations which enable estimates of the depths up to the point of inception and depths, mean air concentrations and air concentration distributions downstream of the point of inception for any spillway chute. The flow down a long spillway can be divided into a number of distinct regions. In the non aerated region close to the spillway crest the boundary layer grows from the spillway floor. Outside the boundary layer the flow is predominantly irrotational and the water surface is smooth and glassy. Downstream of the start of air entrainment a layer containing a mixture of both air and water gradually extends through the flowing fluid. Its rate of growth is small, and normal boundary layer approximations are appropriate. For small slopes, equilibrium is established before the air water mixture reaches the spillway floor.
