AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Computational Modeling of Multispecies Evolving Aerosol Delivery in the Human Respiratory Tract
FRANCESCO LUCCI, Mahdi Asgari, Edo Frederix, Arkadiusz Kuczaj, Philip Morris International R&D
Abstract Number: 430 Working Group: From Aerosol Dosimetry and Toxicology to Health
Abstract Numerous experimental and computational approaches have been developed to understand aerosol inhalation processes targeting various types of aerosols (e.g., solid particles). Transport and deposition of evolving aerosols generated from chemical mixtures are particularly challenging due to complexities arising from the interplay of physics and chemistry properties driven together by the airflow thermodynamics. These processes govern both the gas-liquid phase partitioning of mixture constituents and particle size distribution properties, eventually impacting aerosol delivery and deposition. To investigate aerosols generated from multispecies complex mixtures in particular, we have developed the open-source computational fluid dynamics code AeroSolved (www.aerosolved.com), in which aerosol nucleation, condensation/evaporation, and coagulation processes can be investigated within a density-coupled framework. This gives a unique capability to study the flows in the human respiratory tract in detail, with particular attention to aerosol evolution and deposition by diffusion, sedimentation, and impaction. Following our recent work concerning multispecies aerosol evolution and deposition in a bent pipe (Asgari et al., JAS (129), 2019), we extended its scope to simulate liquid particle (consisting of propylene glycol, glycerol, and water) flows in a respiratory tract geometry up to six generations of the tracheobronchial tree. Our computational models were validated by comparing with the available literature data for aerosol evolution and deposition under controlled experimental conditions. We considered air flow rates ranging from 1.5 to 30 L/min as equivalent to puffing and inhalation flow rates, including steady and transitional flows. Our results showed that particle size evolution can significantly influence the deposition efficiency favoring or inhibiting the inertial and diffusional deposition mechanisms. We also showed that species-specific deposited liquid mass is also changed remarkably due to particle evolution. We present a comprehensive set of simulation scenarios and learnings concerning complex mixture aerosol behavior during the inhalation process and relevant for the dosimetry purposes.