Simulations of Airborne Pollutant Levels and Infiltration Flows in an Enclosure

A study of infiltration-type air flows through a room-size enclosure with an obstructing wall was conducted. A finite volume (cell finite difference) method was used, and a k-ε turbulence model was retained in the simulations. Detailed monitoring of how a simulated gaseous pollutant was diluted and dispersed over time was accomplished, and showed that nearly stagnant zones exist. The simple air change (ACH) method of rating the ventilation capabilities of an enclosure was judged to be marginally acceptable, with a local air age scheme a suggested alternative for multizone cases. Based on the simulations, it was argued that the tracer-gas empirical method of determining ventilation capability may be prone to large uncertainties if flow obstructions or multiple zones exist and only a few sampling locations are used.