Lift Forces on Moving Particles Near Boundaries

Abstract

The lift force on a moving, heavy particle at the instant when the particle is drawn upwards from near the bottom is been experimentally determined for both smooth and rough-bottom cases in a turbulent open-channel flow. The lift-force data obtained are plotted against the distance from the boundary. It is found that, a) in the smooth wall case, the lift force appears to reach a weak maximum, and then decreases with the distance from the wall, while, in the rough wall case, it decreases appreciably with the distnce from the wall, b) the lift force increases markedly with increasing bed roughness, and c) the extra effect of rough wall upon the lift force tends to disappear with the distance from the wall.