Coupled CFD and particle resuspension models under combined effect of mechanical and aerodynamic disturbances

Abstract

Particle resuspension in indoor spaces constitutes a concern to human health as it re-introduces deposited particles on surfaces into the bulk air. Resuspension can occur due to indoor human activities causing aerodynamic and mechanical vibration disturbances. The objective of the work is to develop a simplified model that can predict resuspension triggered by the simultaneous action of aerodynamics and vibration forces from hard floor material. The mathematical model was coupled with computational fluid dynamics (CFD) model to predict, through a probabilistic approach, the rates of particle resuspension from indoor surfaces due to indoor activities. The developed model accounted for the reduction of adhesive forces due to vibrations and for the lift and drag forces and moments due to the fluid flow while setting the resuspension condition to predict the resuspension rates. The resuspension model was validated by published literature data on particle resuspension due aerodynamic and mechanical disturbances and good agreement was found. Resultsshowed that particle resuspension exhibited a rapid burst during the first 25 s of the disturbance before decreasing to negligible values. Resuspension rates also increased when vibrations were accounted for with aerodynamic disturbances. For different indoor surfaces, it was found that resuspension fractions were the smallest for glass surfaces, followed by marble and linoleum. Moreover, resuspension fractions increased by 48.4%, 60.5% and 63% for glass, marble and linoleum when aerodynamic disturbances were accompanied with vibrations. A decrease in surface roughness can increase adhesive forces, and stiffness values reducing the effect of vibrations on enhancing resuspension.