Simulation and Modeling for Aging and Particle Shape Effect on Airflow Dynamics and Filtration Efficiency of Human Lung

Abstract

The respiratory system undergoes various physiological and immunological changes with age. After birth, alveolization is one of the main factor associated with progressive growth of lung, which is relatively poorly analysed in respect of lung function. In this study we considered growth of lung caused by progressive increment in number of alveoli and simultaneously calculated its effect on airflow dynamics and filtration efficiency of human lung from childhood to age of 30. Incorporating the idea of filtration through lung with respect to age biofilter model is used by assuming porosity of lung varied with respect to number of alveoli and their surface area. Transportation and deposition properties of nanoparticles of various shapes during inhalation is taken under consideration by using particle shape factor. Generalized Navier Stokes equation is used for flow dynamics and finite difference scheme is used to solve the problem numerically. Simulation is done by using user defined code on MATLAB at very fine grid. Results indicate that the filtration efficiency of lung decreases as age increases from childhood to age of 30; additionally, nonspherical nanoparticles with high aspect ratio's will take a longer time to be filterd from lung as compared to spherical nanoparticles of the same diameter.