Particle motions near the bottom in turbulent flow in an open channel

Abstract

A photographic technique has been used to make observations of the motion of heavy suspended particles in an open channel with a smooth bottom. The observations showed that the path of an individual heavy particle consists of an alternation between upward and downward paths traced by the particle as it travels close to the bottom. The path records appear to reveal most of the flow patterns near the wall shown up by earlier visualization observations; the measured kinematical quantities concerning the particle motion are in accord with those of earlier observations (e.g. Nychas, Hershey & Brodkey 1973). Making use of the present observations and following Offen & Kline's (1975) model of the bursting process in turbulent boundary layers, an attempt was made to explain the mechanism of particle suspension close to the wall in turbulent flows.