Wind tunnel studies of particle transport and deposition in turbulent boundary flows

In this study, particle transport and deposition were studied in a wind tunnel by measuring both the airflow turbulence characteristics and deposition of monodisperse uranine particles of 2.0-4.5 μm diameter on smooth, horizontal surfaces. Turbulence characteristics behind a 2.54 cm high rectangular bar were investigated for free stream velocities ranging from 3.3 m/s to 15.3 m/s. The well-developed boundary layer thickness was approximately four times the height of the rectangular bar at a distance of about 55 cm from the bar. Results of the wind tunnel experiments show the complex nature of deposition in turbulent flows due to the interactions between particles and turbulence. In general, the particle deposition flux is larger in the near wake region than in the far wake region. The particle deposition flux is roughly independent of the dimensionless particle relaxation time when the relaxation time is less than one, but increases rapidly as the relaxation time increases above one.