Influence of the geometry of the airways on the characterization of exhalation flows. Comparison between two different airway complexity levels performing two different breathing functions

Human exhalation can emit pathogens in droplets that can represent the origin of airborne cross infections. Simplified respiratory airway models have been used in experimental and numerical studies in order to simulate exhalation flows. This study presents a comparison between two different airway models, a simplification (SA) and a realistic 3D scanned model (RA) in performing two different exhalation patterns corresponding to two different female metabolic rates, corresponding to a standing relaxed (SR) activity (1.2 met) and walking active (WA) metabolic level (2 met). A time resolved particle image velocimetry (TR-PIV) study of the flow emitted to the surroundings in each case is obtained for each airway and exhalation combination. Results show that the scanned 3D model (RA) presents a different and more realistic flow development. Transient puff structures have been identified for both airway models. Results can be useful for further research on pollution control in indoor and outdoor spaces.