Open Channel Flow Through Transverse Floor Outlets

The study of subcritical flow through floor outlets or bottom racks in rectangular open channels has direct applications in horizontal trash‐racks of hydro power plants, in curb outlets of streets and in general to divert flow from one stream to another. An understanding of the flow behavior over bottom racks or floor outlets is very important for the proper design of such flow diversion works. In earlier studies, an expression for the discharge through a single traverse floor outlet located in an open channel has been studied under free flow conditions. In the present study, the dependence of the diverted discharge on the downstream conditions is investigated. Specifically, the outflow is expressed as a function of flow characteristics in the channel upstream and downstream of the floor outlet. A simple design chart is developed to aid hydraulic engineers to divert the required flow through bottom outlets of open channels. Experimental data are presented to verify the model.