ABSTRACT
In Chapter 7, we considered steady uniform flow in a channel. It was understood that the flow was often turbulent; that there was considerable variability in the velocity at different points in a cross section; that some of flow might even occur in an upstream direction; and that as the flow moved around a bend, it behaved somewhat like a roller coaster. Despite all this variability, useful estimates of the mean velocity and discharge can be obtained using a resistance equation such as Manning’s equation or the Darcy-Weisbach equation. However, there are many times when use of one of these equations is not appropriate. If we consider the energy of the flow, we will see that the following three basic types of flow can occur in an open channel: subcritical, critical, and supercritical. Uniform flow is only one kind of subcritical flow regime.
