Numerical simulation of virus-laden aerosol transmission in real human respiratory airways

In this study, the transport of virus-laden aerosols in real human airways is investigated through numerical simulations. Three different breathing modes (nasal, oral, and nasal-oral) are studied to analyze the behavior of the particle deposition in the respiratory airways of humans through realistic anatomical models. Increasing the flow rate typically leads to the augmentation of velocity profiles, turbulence, and pressure changes, specifically expanding the high velocity regions in the pharynx, larynx, and trachea. As a result, the deposition fractions of the total number of aerosols deposited in these regions increase, while a decrease in aerosol deposition is observed in the nasal and oral cavities. For the effects of increasing particle sizes, 2-10 μm particles exhibit a higher degree of clustering in the trachea for the nasal mode, in the larynx for the oral mode, and in the trachea for the nasal-oral mode, compared to the clustering of 1-10 μm particles. Considering the high deposition fraction in the upper airway regions, which are the primary factors contributing to the easy transmission of the virus through casual talking and coughing, the results demonstrate that the highest deposition fraction, exceeding 85%, is observed in the nasal mode with small aerosols ranging from 1 to 2 μm in diameter, and at the lowest flow rate of 15 LPM. In the lower airway regions, targeted drug delivery with the highest deposition fraction in the bronchial regions can be a solution for reducing respiratory diseases, such as asthma and chronic obstructive pulmonary disease, which are caused by inflammatory conditions in the bronchi.