Numerical study of the human walking-induced fine particles resuspension

One of the main sources of pollution in indoor environments is human walking-induced particle resuspension. In this work, the airflow and resuspension of particles smaller than 1 μm generated by foot tapping were investigated numerically using ANSYS CFX software. The k-ω shear stress transport model was considered to simulate the unsteady airflow field around and under the shoe. The immersed solid method was then used to incorporate the shoe in a three-dimensional computational domain. Particle resuspension was predicted by means of the Rock ‘n’ Roll model. The effects of the walking speed and shoe groove pattern (transverse grooves, longitudinal grooves and no groove) were studied. Three different selected particle-substrate combinations (ATD-linoleum, PSL-linoleum and alumina-steel) were tested. The numerical simulations showed that the air below the foot was ejected as a high velocity jet. After the shoe hit the ground, counterrotating vortices were formed around the shoe. The results of particle resuspension were compared with previous experimental works, and good agreement was found. Results shown that for the different studied cases the resuspension fraction ranges over four orders of magnitude, from 10⁻⁵ to 10⁻¹. Particle resuspension fractions increased with particle size and walking speed. However, no significant influence of the shoe groove patterns was observed.