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Three Dimensional Fluid-structure Interaction Analysis of Air Flow and Inhaled Particle Transport in Human Pulmonary Alveoli

Monjezi, Mojdeh | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48920 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Saeed
  7. Abstract:
  8. The prediction of deposition efficiency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems, and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three dimensional honeycomb like configuration and a fluid-structure interaction analysis is performed to study the normal cyclic breathing hydrodynamics. A viscoelastic model is used for the mechanical behavior of alveolar wall tissue. In contrast to previous works in which the inlet flow rate is predefined, in this model a negative pressure is imposed on the outside surface of the alveolus which causes air to flow in and out of the alveolus. The resulting flow patterns confirmed that there is no circulation in the terminal alveolus. The predicted alveolar airflow was used to calculate the trajectories of submicron particles using the Lagrangian approach. For accurate estimation of aerosol deposition in acinar airways, study was confined to fine particles under zero and normal gravity conditions. Under zero gravity, the deposition efficiency increased by the decrease in particle diameter. Under normal gravity condition, however, the deposition efficiency first decreases with increasing size and then increases with further increase in particle size. Furthermore, the findings suggest an accurate simulation requires including at least ten breathing cycles, considering a parabolic radial distribution of injected particles and continuous injection. The presented results show high deposition efficiency for submicron sizes in the alveolar region if these particles could reach the alveolar region. Therefore, the vesicles technology in which particle agglomerates would be released after the vesicle reaching the alveoli is suggested for targeted drug delivery to the pulmonary alveolar region
  9. Keywords:
  10. Lagrangian Method ; Particles Tracking ; Fluid-Structure Interaction ; Three-Dimensional Simulation ; Alveolar Zone ; Naturally Respiration

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