Micro-particle indoor resuspension under periodic airflows: A numerical-analytical study and experimentations

As particles may pose a threat to people during breathing close to surfaces, understanding and identifying the mechanisms by which these particles detach helps in taking preventive measures during cleaning and dusting processes of surfaces, and in the selection and operation of ventilation systems when particles are airborne. This work presents a numerical–analytical coupled model to examine resuspension under the effect of oscillatory flows, taking into account the probabilistic approach of resuspension occurrence due to turbulent bursts for different particle diameters and surface roughness. The results of the model were validated with experiments conducted for flows alternating between constant blowing and suction for different flow velocities and frequencies. A parametric study using the validated model was conducted to study the particle detachment phenomenon of a variety of particle characteristics under sinusoidal flows similar to that of human breathing over different flooring materials. Results showed that micro-particles of relatively high diameters pose a considerable threat over surfaces in indoor environment. The occurrence of resuspension is highly influenced by surface type and roughness. Parquet flooring was found to cause the resuspension of approximately 98% of 80μm lead particles compared to 64.5% of the same particles over marble flooring at certain locations under the effect of normal breathing. Therefore, besides dust removal methods, the choice of flooring material is an essential preventive measure to reduce indoor particle resuspension.