Velocity profile and flow resistance models for developing chute flow

A developing boundary layer starts at the spillway crest until it reaches the free surface at the so-called inception point, where the natural air entrainment is initiated. A detailed reanalysis of the turbulent velocity profiles on steep chutes is made herein, including mean values for the parameters of the complete turbulent velocity profile in the turbulent rough flow regime, given by the log-wake law. Accounting both for the laws of the wall and the wake, a new rational approach is proposed for a power-law velocity profile within the boundary layer of turbulent rough chute flow. This novel approach directly includes the power-law parameters and does not require for a profile matching, as is currently required. The results obtained for the turbulent velocity profiles were applied to analytically determine the resistance characteristics for chute flows. The results apply to the developing flow zone upstream of air inception in chute spillways. DOI: 10.1061/(ASCE)HY.1943-7900.0000190 CE Database subject headings: Air inception; Boundary layers; Flow resistance; Open channel flow; Velocity. Author keywords: Air inception; Boundary layer; Chute flow; Flow resistance; Open channel flow; Turbulent velocity profiles.