Aerodynamic Resuspension of Particles Due to a Falling Flat Disk

Abstract

In this article, computational fluid dynamics (CFD) is used to compute the unsteady, compressible flow caused by a flat falling circular disk. CFD results are coupled with a particle trajectory model to determine particle trajectories for different particle sizes and examine which particles are trapped or ejected from the closing gap. CFD results show that the normalized radial velocity profiles are self similar for different Reynolds numbers based on the gap height, and that flow compressibility results in a density increase toward the center of the disk for decreasing gap height. To efficiently couple CFD results with the particle trajectory model, a regression model representing both the velocity field and density variation inside the gap is developed and coupled with a particle detachment model. Particle trajectories are shown to be sensitive to the flow compressibility and must be taken into account. The escaped and trapped particle distribution is computed for a thin mono-layer of Arizona Test Dust under the disk. The simulations show that higher impact velocities tend to cause more of the heavier and larger particles to be trapped under the disk because they are catapulted from the floor and are quickly driven down again by the descending disk.

Experimental investigation and modelling of human-walking-induced particle resuspension

“…The stomping-like motion was used in a number of previous studies and was found able to characterize the fundamental aerodynamics (jet and vortex motion) during walking pertinent to particle resuspension. 15,23 The aerodynamic mechanisms of resuspending particles are similar between the stomping-like walking and the walking with foot rotation. It was shown that both particle resuspension and particle redistribution occurred during the upward and downward motions for both stomping-like walking and the walking with foot rotation, 24 which suggested the similarity between these two walking styles in terms of the particle resuspension mode.…”

Surface interactions of aerosols and their impact on infectious disease transmission

“…It should be noted that this work used the stomping-like walking with a pair of motorized model legs to represent idealized human walking. The stomping-like motion was used in a number of previous studies and was found to be able to characterize the fundamental aerodynamics (jet and vortex motion) during walking pertinent to particle resuspension [122,182,183]. The aerodynamic mechanisms of resuspending particles are similar between the stomping-like walking and the walking with foot rotation.…”