Local Scour Downstream of an Apron

Abstract

Measurements have been made of the rate of scour downstream of a rigid apron due to a jet of water issuing through a sluice opening. Experiments are carried out for various sand sizes, sluice openings, efflux velocities, and lengths of apron. Mean velocity profiles in rigid models simulating the shape of the scour hole are studied in detail. They are found to exhibit similarity. Scales of velocity and length that are adopted bring together all the data concerning the decay of maximum velocity in the scour hole with respect to streamwise distance. A simple semi‐empirical theory based on a characteristic mean velocity in the scour hole is proposed to predict the time rate of scour. Predicted results are compared with experimental data.