An Experimental Investigation of the Flowfield and Dust Resuspension Due to Idealized Human Walking

Abstract

In order to address how human foot movement causes particles to be resuspended from the floor, particle flow visualization and particle image velocimetry (PIV) measurements were performed on a simplified model of the human walking motion; a disk moving normal to the floor. Flow visualization of particles, seeded initially on the ground, indicates that particles are resuspended by both the downward and upward motions of the walking process. On both the upstep and the downstep, particle resuspension occurs due to a high velocity wall jet, forming between the wall and the disk in general accord with the mechanism for particle resuspension put forth by Khalifa and Elhadidi (2007, “Particle Levitation Due to a Uniformly Descending Flat Object,” Aerosol Sci. Technol., 41, pp. 33–42). Large-scale ring vortex structures were formed on both the downstep and the upstep, and did not cause particle resuspension, but were extremely effective at quickly moving the already resuspended particles away from the wall. By varying the seeding of the particles, it was determined that only particles underneath and toward the outer edge of the disk are resuspended.

Characterizing particle resuspension from mattresses: chamber study

“…The air velocities increased suddenly, suggesting impulsive and highly accelerated airflow, similar to airflows generated by footfalls or descending objects (e.g., Choi and Edwards, 2012;Khalifa and Elhadidi, 2007;Kubota et al, 2009). The impulsive nature of the flow may be considerably more important in inducing resuspension from the bed sheets than the maximum velocities achieved.…”

Monolayer and Multilayer Particle Deposits on Hard Surfaces: Literature Review and Implications for Particle Resuspension in the Indoor Environment

“…Several studies investigated the airflow generated by foot motions. Kubota et al (2009) and Kubota and Higuchi (2013) reported jet velocities of approximately 2-3 m/s associated with the downward foot motion, Gomes et al (2007) reported peak air velocities of 1.5-2 m/s associated with walking-related airflow near the floor, and a modeling study by Zhang et al (2008) found a maximum radial velocity of 18.3 m/s beneath the foot. Additionally, the airflows are likely very impulsive with high acceleration (Khalifa and Elhadidi 2007), and an important factor affecting resuspension (Ibrahim et al 2003).…”

“…Full-scale walking-induced resuspension studies have reported resuspension from both monolayer (Karlsson et al 1999;Tian et al 2011) and multilayer deposits Kubota et al 2009;Tian et al 2011;Shaughnessy andVu 2012, Kubota andHiguchi 2013) on hard flooring. Gomes et al (2007) found aerodynamic removal forces associated with airflow disturbances generated by human walking to be the primary mechanism for particle resuspension from flooring, although surface vibrations, mechanical abrasion, and electrostatic forces can contribute to resuspension (Gomes et al 2007;Hu et al 2008;Qian and Ferro 2008;Hubbard et al 2012).…”

Aerodynamic Resuspension of Particles Due to a Falling Flat Disk

“…Once detached, the particles can be levitated by aerodynamic lift forces and can escape from the narrowing gap between the falling object and the floor in a particle-laden high velocity wall jet and be entrained in the flow structure surrounding the falling object (Khalifa and Elhadidi 2007;Kubota et al 2009). Koch (1997, 1999) were the first to study the resuspension of particles outside the rim of a falling disk.…”