Drag Characteristics of Two-Dimensional Sills in Forced Hydraulic Jumps

Sills and other appurtenances are often used to aid the formation of a hydraulic jump in a stilling basin. The drag force acting on a sill in forced hydraulic jump depends on the initial Froude number F1, the height of the sill S, and its distance xs, measured from the toe of the jump. The forward flow in the main body of the hydraulic jump behaves like a wall jet. Therefore, based on observed data, simple relationships were developed to predict the maximum velocity Um and the half-width b of a free hydraulic jump. These are coupled with a dynamic pressure model that expresses the local drag coefficient Cdδ of a sill in a plane turbulent wall jet. The drag coefficient for the sill in a forced hydraulic jump Cd was obtained by a simple transformation involving the wall jet parameters.