Gas transfer, cavitation, and bulking in self-aerated spillway flow

Air entrainment in free-surface spillway flows has been described in a companion paper with two concepts: "entrained air," which is air being transported by the flow as bubbles; and "entrapped air," which is the air transported with the flow in the roughness or waves of the water surface. This paper shows the application of this "bubbles and waves" description of entrained and entrapped air for flow at any location along a spillway face to: (a) estimate the bulking of flow due to insufflation of air, (b) estimate the location where aeration is sufficient to eliminate cavitation damage, and (c) compute the oxygen absorption in self-aerated flow. The bubbles and waves description of self-aerated flow is essential to the accurate computation of gas transfer on a spillway surface, and can provide the appropriate bulking and cavitation computations for spillway design and management.