CFD simulations of contaminant transport between two breathing persons.

Experiments have shown that exhalation from one person is able to penetrate the breathing zone of another person at a distance. Computational Fluid Dynamics (CFO) is used to investigate the dependency of the personal exposure on some physical parameters, namely: Pulmonary ventilation rate, convective heat output, exhalation temperature, and cross sectional exhalation area. Full-scale experimental results are used to calibrate/validate the CFD model. Respiration, although an inherently transient phenomenon, is simulated by steady-state CFD with reasonably good results. Different geometries and grid distributions are tested to see what level of complexity is necessary. To further evaluate the experimental results, the CFD simulations are then used to perform parameter variations. The simulations show that the simulated personal exposure is very sensitive to variations in the convective heat output of both the exposed person and the exhaling person, and in the cross-sectional exhalation area and the pulmonary ventilation rate of the exhaling person.