Capillary instability of a two-layer annular film: an airway closure model
| Autor: | O. Erken, F. Romanò, J.B. Grotberg, M. Muradoglu |
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| Přispěvatelé: | Erken, Oğuzhan, Muradoğlu, Metin (ORCID 0000-0002-1758-5418 & YÖK ID 46561), Romano, F., Grotberg, J. B., Graduate School of Sciences and Engineering, College of Engineering, Department of Mechanical Engineering |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Journal of Fluid Mechanics |
| Popis: | Capillary instability of a two-layer liquid film lining a rigid tube is studied computationally as a model for liquid plug formation and closure of human airways. The two-layer liquid consists of a serous layer, also called the periciliary liquid layer, at the inner side and a mucus layer at the outer side. Together, they form the airway surface liquid lining the airway wall and surrounding an air core. Liquid plug formation occurs due to Plateau-Rayleigh instability when the liquid film thickness exceeds a critical value. Numerical simulations are performed for the entire closure process, including the pre- and post-coalescence phases. The mechanical stresses and their gradients on the airway wall are investigated for physiologically relevant ranges of the mucus-to-serous thickness ratio, the viscosity ratio, and the air-mucus and serous-mucus surface tensions encompassing healthy and pathological conditions of a typical adult human lung. The growth rate of the two-layer model is found to be higher in comparison with a one-layer equivalent configuration. This leads to a much sooner closure in the two-layer model than that in the corresponding one-layer model. Moreover, it is found that the serous layer generally provides an effective protection to the pulmonary epithelium against high shear stress excursions and their gradients. A linear stability analysis is also performed, and the results are found to be in good qualitative agreement with the simulations. Finally, a secondary coalescence that may occur during the post-closure phase is investigated. Scientific and Technical Research Council of Turkey (TÜBİTAK); National Institutes of Health (NIH) |
| Databáze: | OpenAIRE |
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