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  • Statistical overloading is used to obtain spatio-temporal pathogen concentration.

  • Symmetrically placed AC limits pathogen propagation over long distances.

  • Well-mixed model captures room-averaged concentration for any shape and AC location.

  • The pathogens level of mixing is reduced when AC is symmetrically positioned.

  • Air leakage has insignificant impact on indoor pathogen distribution.


We conducted Euler–Lagrange Reynolds-Averaged Navier–Stokes simulations with statistical overloading to investigate the effect of room shape, air-condition (AC) location, and the presence of an open window on indoor airborne viral transmission, particularly as it relates to the spatio-temporal distribution of viral-laden droplet nuclei. Two room geometries were considered with two different AC types positioned at different locations within each room. We considered the case of perfect filtration where pathogens can exit the room through ventilation, air leakage through an open window, turbulent wall deposition, and by gravitational settling onto the bottom floor. We observe the room-averaged concentration to decay at the rate estimated from the well-mixed model and therefore to be independent of room size and shape or AC type and placement. It is also independent of whether or not there is an open window. However, we find that the departure from well-mixedness, which has been quantified using a time- and source-to-sink separation-dependent correction function γ, is affected by room shape and AC placement. More specifically, indoor spaces where the AC is installed on one end of the room allow droplet nuclei ejected on one end of the room to travel longer distances before being removed from the room as opposed to indoor spaces in which the AC is installed at the center of the room. The present results allow generalization of a simple model for the accurate prediction of viral quanta inhaled by an individual in any indoor environment.


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Building and Environment



Available for download on Wednesday, October 01, 2025