Aerosol and pollutants, in form of particulates 5–8 μm in main size face every day our respiratory system as natural suspension in air or forced to be inhaled as a coadjutant in a medical therapy for respiratory diseases. This inhalation happens in children to elderly, women and men, healthy or sick and disable people. In this paper we analyzed the inhalation of aerosol in conditions assimilable to the thermal therapy. We use a computational fluid dynamic 3D model to compute and visualize the trajectories of aerosol (3–7–10–25 µm) down to the sixth generation of bronchi, in a steady and dynamic condition (7 µm) set as breath cycle at rest. Results, compared to a set of milestone experimental studies published in literature, allow the comprehension of particles behavior during the inhalation from mouth to bronchi sixth generation, the visualization of jet at larynx constriction and vortices, in an averaged characteristic rigorous geometrical model including tracheal rings. Results on trajectories and deposition show the importance of the including transient physiological breath cycle on aerosol deposition analyses. Numerical and graphical results, may enable the design of medical devices and protocols to make the inhalations more effective in all the users’ population.

Background: Aerosol and pollutants, in form of particulates 5 – 8 um in main size face every day our respiratory system as natural suspension in air or forced to be inhaled as a coadjutant in a medical therapy for respiratory diseases. This inhalation happens in children to elderly, women and men, healthy or sick and disable people. In this paper we analyzed the inhalation of aerosol in conditions assimilable to the thermal therapy, in a model of patient representing an adult man. Results: We use a computational fluid dynamic 3D model to compute and visualize the trajectories of aerosol (3-7-10-25 µm) down to the sixth generation of bronchi, in a steady and dynamic condition (7 µm) set as breath cycle at rest. Results, compared to a set of milestones experimental studies published in literature, allow the comprehension of particles behavior during the inhalation from mouth to bronchi sixth generation, the visualization of jet at larynx constriction and vortices, in a characteristic geometrical model including tracheal rings. Conclusions: Results on trajectories and deposition show the importance of the including transient physiological breath cycle on aerosol deposition analyses. Furthermore results indicate that vorticity in the glottides and trachea sections mix the trajectories on the transversal plane, excluding meaningful relation between position of the inhalation across the mouth and the deposition lobe. Numerical and graphical results, usable from researchers, technicians and medical doctors, may enable the design of medical devices and protocols to make the inhalations more effective in all the users’ population.

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