Simulation of turbulent airflow and particle deposition in human and animal airways
Abstract/Contents
- Abstract
- Prolonged exposure to inhaled micron-sized airborne particles is a known public health concern. These particles impact the health of staggering numbers of residents of polluted urban areas, as well as significant portions of the third world where it is still common to burn wood or charcoal indoors for cooking or heating. An understanding of the fate of inhaled particles in the lungs is useful for assessing their associated health risks, as well as improving the effectiveness of respiratory drug delivery techniques. The transport of microparticles is inseparable from behavior of the suspending airflow and this is studied using computational fluid dynamics techniques. The anatomy of the airways seems to have evolved to encourage turbulent airflow for functions such as mixing of flow to promote the warming and humidification of inhaled air, as well as for filtration. Large eddy simulation models are employed to capture turbulent flow in extremely complex patient-specific airway geometries. These collectively comprise the oral and nasal cavities, larynx, trachea, and the bronchial tree. The flow in anatomically-accurate rhesus macaque airways is also studied. Simulations are carried out for inspiratory flow rates corresponding to nominal Reynolds numbers in the hundreds to low-thousands yet somewhat surprisingly yield unsteady flows due to local geometric factors. A computed mean flow field is compared extensively with magnetic resonance velocimetry measurements carried out in the same computed-tomography--based lung geometry, showing good agreement. Microparticle deposition predictions are also verified. Focus is placed on the dynamics of the flow in the nasal airway, trachea, and bronchial tree. After becoming unsteady at constrictions in the upper airways, the flow is found to be chaotic, exhibiting fluctuations with broad-band spectra even at the most distal simulated airways in which the Reynolds numbers are as low as 300. The unsteadiness is attributed to the convection of turbulent structures produced in the upper airways as well as to local kinetic energy production throughout the bronchial tree.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Geisler, Taylor Steven |
|---|---|
| Degree supervisor | Iaccarino, Gianluca |
| Degree supervisor | Shaqfeh, Eric S. G. (Eric Stefan Garrido) |
| Thesis advisor | Iaccarino, Gianluca |
| Thesis advisor | Shaqfeh, Eric S. G. (Eric Stefan Garrido) |
| Thesis advisor | Marsden, Alison (Alison Leslie), 1976- |
| Degree committee member | Marsden, Alison (Alison Leslie), 1976- |
| Associated with | Stanford University, Department of Chemical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Taylor S. Geisler. |
|---|---|
| Note | Submitted to the Department of Chemical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Taylor Steven Geisler
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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