Estimating Trajectory of Free Overfall Nappe

Abstract

The upper surface profile of a rectangular free overfall is modeled using the free-fall parabolic equation. Empirical and semiempirical relationships for the unknown quantities in this equation are presented. It was found that the resulting simple and straightforward method adequately predicts the position of the upper nappe surface. A relationship for establishing the vertical thickness of the nappe (due to another researcher) is given, thus enabling the entire nappe profile from the brink to be described. The equations are of use in the design of spillways and diversionary structures utilizing a free overfall.