Vertical drain and overflow pipes: Literature review and new experimental data

This paper describes and discusses the available experimental investigations concerning vertical pipe flow in order to understand possible differences caused by different intake types and inflow conditions. Specific attention is given to the difference between drain pipes and overflow pipes and to the influence of the inflow conditions on the head-discharge relation. Data from the available literature are systematized and treated in a unified manner to provide a comprehensive view of possible flow regimes, among which four main types are selected, namely Borda free and full flow, governed by pipe cross section; weirlike flow, governed by pipe diameter; and full pipe flow, governed by pipe cross section and length. For each, both data from the literature and novel data are used to calibrate both dimensional and nondimensional head-discharge equations, along with prediction equations for the discharge coefficients. The equations describing the critical head, marking the passage to full pipe flow, and the vortex critical head, marking the passage to a vortex-free full pipe flow, are provided. © 2018 American Society of Civil Engineers.