Author(s): Oscar Castro-Orgaz; Willi H. Hager
Keywords: Curvilinear flow; One-dimensional flow; Open channel; Spillway; Transitional flow; Weirs
Abstract: Flows from mild to steep slopes are relevant in hydraulic engineering relating to chute spillways and slope changes in irrigation networks. These flows are associated with transitional flow from sub- to super-critical conditions, smooth curvilinear-streamline feature involving a continuous free surface profile, and a rapid variation of the bottom pressure profile. Herein, the transition from a horizontal to a steeply sloping rectangular channel reach is investigated to analyze the application range of the Boussinesq-type equation. Slope breaks with a rounded transition from the brink section to the tailwater channel are considered and compared with the potential flow solution based on the Laplace equation. The Boussinesq-type equation is further compared with test data for a steep downstream slope to investigate the strong curvilinear gravity effect. A singular point analysis is also compared with the Boussinesq approach. The generalized momentum equation for curvilinear flows is developed and compared with the results pertaining to the energy concept.