Sharif University of Technology Scientia Iranica 1026-3098 23 4 2016 08 01 Fluid-structure interaction analysis of air flow in pulmonary alveoli during normal breathing in healthy humans Fluid-structure interaction analysis of air flow in pulmonary alveoli during normal breathing in healthy humans 1826 1836 3929 10.24200/sci.2016.3929 EN M. Monjezi School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran. M.S. Saidi School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran. Journal Article 2016 08 27 In this work, the human lung alveoli are idealized by a three dimensional honeycomb like geometry and a fluid-structure analysis is performed to study the normal breathing mechanics. In contrast to previous works in which the inlet flow rate is predened, in this model, we have applied a negative pressure on the outside surface of the alveolus which causes air to flow in and out of the alveolus. The integration of the experimental curve of breathing flow rate was used to approximate the shape of the external applied pressure. Our Fluid-Structure Interaction (FSI) model has an advantage over other literature since it addresses both the fluid dynamics and solid mechanics, simultaneously. The flow patterns conrmed that there is no circulation in the terminal alveolus. We have applied three distinct material models { linear isotropic elastic, hyperelastic, and viscoelastic  in order to simulate the mechanical behavior of alveolar wall tissue using ADINA software. The hysteresis behavior of the alveolar tissue was well predicted by a compliance diagram of the viscoelastic model while this behavior is not observed in the linear elastic and hyperelastic model. The stress and strain distribution is also obtained and is found to be non-uniform. https://scientiairanica.sharif.edu/article_3929_264d9a4a879d06b161297e8927297eea.pdf