Relationship between Particle Motion and Turbulence Structure in Turbulent Boundary Layer Flow over Particle-Rough Wall.

Abstract

Particle motions with high Reynolds numbers of particles in the turbulent boundary layer over the spherical-particle-rough wall were experimentally and numerically studied with the coherent turbulence structure. The particle trajectories, velocities and accelerations in the buffer region near the wall were measured using an image processing system combined with a high-speed video system and a workstation, and instantaneous air velocities in the streamwise and vertical directions were simultaneously measured using a miniature X-probe connected to a constant-temperature hot-wire anemometer. In addition, three-dimensional numerical simulations were performed for linear shear flow past a sphere to estimate the lift force induced by both fluid shear and particle rotation. The results show that the particle motions are strongly influenced by the organized motions in the boundary layer flow.