PARTICLE BEHAVIOR IN THE TURBULENT BOUNDARY-LAYER .1. MOTION, DEPOSITION, AND ENTRAINMENT

The motion of solid particles near the wall in a turbulent boundary layer was investigated experimentally in a water flume by flow visualization techniques and by LDA. The particles were of polystyrene (specific density ∼1.05) with diameters ranging from 100 to 900 μm. Results show that particle motion, as well as entrainment and deposition processes, are controlled by the action of coherent wall structures, which appear to be funnel vortices. The behavior of the particles is consistent with the motion and effects of such vortices. The vortices appear to cause the formation of particle streaks near the wall, to create suitable conditions for particle entrainment, and to assist in particle deposition by conveying them from the outer flow to the wall region. © 1995 American Institute of Physics.