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A numerical model of the aerosol transport and deposition in human airways is presented. The model was acquired from a CT scan a living person and consist of 6-9 bifurcations giving around 100 terminations of the tree. The oral/nasal cavity was not modelled in the presented work. The deposition of the particles is given for two breathing regimes, the resting conditions with a tidal volume of 0.5 liter and 15 l/min ventilation with period of 4 sec/cycle and full exercise conditions with 3.33 liter tidal volume and 120 l/min minute ventilation with cycle period of 1.25 sec/cycle. The aerosol concentration was assumed 50 μg/m^3 distributed in the three size classes PM10, PM 5 and PM 1. The results shows deposition in different segments of the tracheo-bronchial tree as well as velocity profiles at different time steps of the breathing cycle.

The development of organs in the human body does not end at birth. During the first five years of life, changes occur in the respiratory tract, not only in terms of its dimensions but also in the way it is used. Efforts to provide non-invasive treatment in the form of medical aerosols administered to children´s lungs during this period must be supported by knowledge of the flow pattern that significantly influences their transport and deposition. Research related to flow patterns in the adult human respiratory tract is quite widespread and the phenomena that occur during inhalation in different parts of the respiratory tract have been widely documented. In the case of the paediatric respiratory tract, research is relatively scarce due to the age of the patient and the desire to minimise interference with the paediatric organism. At the Brno University of Technology, we have the geometry of the airway of a ten-month-old infant, a scaled model of an adult to match the geometry of a five-year-old child based on scientific knowledge and also an adult model of the human respiratory tract. These geometries, together with knowledge of respiratory physiology were used to compare the changes in airflow behaviour that occur in the trachea during the first five years and compare it to fully developed adult human geometry. Computational Fluid Dynamics was used to investigate the model using a Large Eddy Simulation approach. The periods of life captured by the geometries differ not only in their dimensional difference but also in their approach to airway use. The impact of these differences has been captured in the paper.