Some aspects of aerated open-channel flow at shallow depths and low velocities

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

Open-channel Profiles By Newton\u27s Iteration Technique

Computation of surface profiles for steady gradually varied flow can be accomplished by use of Newton\u27s Iteration Technique. The magnitude of error is controlled and the profile depth can be conveniently calculated at selected distances upstream or downstream from a control point. A Fortran IV program is provided for utilizing the technique in a trapezoidal channel. © 1971

Transient hydraulic simulation: breached earth dams

A conceptual method to alleviate flood damages due to over-topping failures of small earthfill dams is the incorporation of a relatively thin erosion retarding layer within the dam. This paper investigates the reduction in the reservoir release due to the hypothetical erosion retarding layer. In addition, the paper provides a method for the determination of an optimal location of the layer so as to minimize the maximum possible reservoir release due to a gradually breached earth dam. The transient reservoir flow is simulated by a numerical model, based upon the solution of the one-dimensional St. Venant unsteady open-channel flow equations. These equations are solved by the method of characteristics, with appropriate boundary conditions incorporated into the solution procedure. The numerical simulation model is used to determine the reduction in reservoir release due to a single retarding layer and its optimal location for a wide range of pertinent geometric, hydraulic and dynamic parameters. The sensitivity of the results to variations in the above parameters is discussed --Abstract, page ii