Ventilation strategies for inhalation exposure risk mitigation: Eulerian-Lagrangian LES analysis of particle-laden turbulent flow applying virtual manikins

Indoor environmental control has become primordial to minimize inhalation risk of pollutants through the implementation of next-generation ventilation systems. The performance of these ventilation strategies should be evaluated in terms of risk mitigation using a multi-indicator approach to support the realistic outcome of this evaluation. The present study has evaluated five main ventilation strategies (mixing, displacement, underfloor air, impinging jet and stratum ventilation) widely used in current society and four further cases based on occupant position with respect to supply flow. Their performance was assessed through computational fluid dynamics and two interacting virtual manikins with autonomous respiratory functions to calculate age of air, particle dispersion in a room, particles in the local breathing zone, maximum long-term exposure, deposition rate on human tissue and transfer probability. Results showed that well-mixed air in up-supply strategies increase age of air, particle dispersion in the room, transfer probability and deposition in the human body. Down- and mid-supply methods show high local age of air while improving the other indicators but create asymmetric flow in some cases. Overall, displacement ventilation was the optimal solution because it presented the lowest transfer probability although slightly increased age of air. Furthermore, deposited particles were mainly located in the nasal cavity, which might lower adverse health effects.