This study is concerned with the effect of entrained air bubbles on the open-channel hydraulics of water flowing at low velocities. The air bubbles are introduced into the flowing water by injecting diffused compressed air along the channel bottom. The variations of the velocity profile and velocity distribution energy coefficient of aerated and nonaerated flow are discussed. Empirical equations have been determined for the air concentration and increased depth of flow or bulking of the aerated open-channel flow. The investigation revealed a significant increase in the Manning roughness coefficient and the related Darcy friction factor for aerated flow relative to those for nonaerated open-channel flow. Empirical equations are presented which relate the Manning roughness coefficient and Darcy friction factor of aerated flow to the depth, velocity, and Reynolds number of nonaerated open-channel flow. The results of this investigation are valid only within the range of depths and velocities studied and are further restricted to the geometry and pressure range of the particular air diffuser system utilized in the study --Abstract, page ii
