Dispersion of Respiratory Aerosols in Indoor Turbulence

Respiratory particles or aerosols are released in the indoor environment during expiratory events such as talking and breathing. Similar particles are also central to indoor pollution. Understanding how these particles move through the indoor environment is essential for quantifying the ability of the pathogen-laden particles to spread respiratory diseases and indoor pollution mitigation. Previous studies have observed the motion of particle clouds due to natural convection and flow induced by symmetric airflow induced by air-conditioning systems. Though, detailed characterization of the turbulence within this environment is relatively unexplored. Especially, for cases where the air inflow through the HVAC system is at a relative higher or lower temperature than the ambient, which is often the case in winter or summer. Thus, the current study focuses on characterizing the indoor turbulence produced due to buoyancy-effect induced by the incoming HVAC air. Additionally, the particulate transport the flow induces for small particle clouds released at different spatial location is simulated. High-resolution large eddy simulations (LES) are used to model the indoor flow and turbulence, and one-way coupled Lagrangian particle tracking for simulating the dispersion of particles. The equations defining the flow are solved using high-order spectral element methods (SEM). Stokes drag, lift, gravity and thermophoretic forces are accounted for in the particle-tracking model. First and second-order turbulence statistics are used to characterize the flow. The general flow structure of the room shows substantial difference due to buoyancy, inducing major difference in dispersion of the particle cloud.