Scour Reduction by Air Injection: Flow Patterns and Turbulence

Abstract

Experiments in a stilling basin model with air injected at its downstream end exhibited plunging flow resulting in a downward roller, return flow along the bottom, and a downstream near-bed flow after the plunging flow impingement point. Turbulence measurements showed that air injection reduces turbulence both at the exit of the stilling basin and near the downstream bed. Thus the effect of air injection as a modifier of the turbulence structure of the flow downstream of the stilling basin is postulated as a plausible explanation for the observed scour reduction.