Aerosol deposition in mucus-lined ciliated airways
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arXiv
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| Format: | Preprint |
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2025
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| author | Hazra, Swarnaditya Picardo, Jason R. |
| author_facet | Hazra, Swarnaditya Picardo, Jason R. |
| contents | We study the transport and deposition of inhaled aerosols in a mid-generation, mucus-lined lung airway, with the aim of understanding if and how airborne particles can avoid the mucus and deposit on the airway wall -- an outcome that is harmful in case of allergens and pathogens but beneficial in case of aerosolized drugs. We adopt the weighted-residual integral boundary-layer model of Dietze and Ruyer-Quil (J. Fluid Mech., vol. 762, 2015, pp. 68-109) to describe the dynamics of the mucus-air interface, as well as the flow in both phases. The transport of mucus induced by wall-attached cilia is also considered, via a coarse-grained boundary condition at the base of the mucus. We show that the capillary-driven Rayleigh-Plateau instability plays an important role in particle deposition by drawing the mucus into large annular humps and leaving substantial areas of the wall exposed to particles. We find, counter-intuitively, that these mucus-depleted zones enlarge on increasing the mucus volume fraction. Particles spanning a range of sizes (0.1 to 50 microns) are modelled using the Maxey-Riley equation, augmented with Brownian forces. We find a non-monotonic dependence of deposition on size. Small particles diffuse across streamlines due to Brownian motion, while large particles are thrown off streamlines by inertial forces -- particularly when air flows past mucus humps. Intermediate-sized particles are tracer-like and deposit the least. Remarkably, increasing the mucus volume need not increase entrapment: the effect depends on particle-size, because more mucus produces not only deeper humps that intercept inertial particles, but also larger depleted-zones that enable diffusive particles to deposit on the wall. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_01883 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Aerosol deposition in mucus-lined ciliated airways Hazra, Swarnaditya Picardo, Jason R. Fluid Dynamics Medical Physics We study the transport and deposition of inhaled aerosols in a mid-generation, mucus-lined lung airway, with the aim of understanding if and how airborne particles can avoid the mucus and deposit on the airway wall -- an outcome that is harmful in case of allergens and pathogens but beneficial in case of aerosolized drugs. We adopt the weighted-residual integral boundary-layer model of Dietze and Ruyer-Quil (J. Fluid Mech., vol. 762, 2015, pp. 68-109) to describe the dynamics of the mucus-air interface, as well as the flow in both phases. The transport of mucus induced by wall-attached cilia is also considered, via a coarse-grained boundary condition at the base of the mucus. We show that the capillary-driven Rayleigh-Plateau instability plays an important role in particle deposition by drawing the mucus into large annular humps and leaving substantial areas of the wall exposed to particles. We find, counter-intuitively, that these mucus-depleted zones enlarge on increasing the mucus volume fraction. Particles spanning a range of sizes (0.1 to 50 microns) are modelled using the Maxey-Riley equation, augmented with Brownian forces. We find a non-monotonic dependence of deposition on size. Small particles diffuse across streamlines due to Brownian motion, while large particles are thrown off streamlines by inertial forces -- particularly when air flows past mucus humps. Intermediate-sized particles are tracer-like and deposit the least. Remarkably, increasing the mucus volume need not increase entrapment: the effect depends on particle-size, because more mucus produces not only deeper humps that intercept inertial particles, but also larger depleted-zones that enable diffusive particles to deposit on the wall. |
| title | Aerosol deposition in mucus-lined ciliated airways |
| topic | Fluid Dynamics Medical Physics |
| url | https://arxiv.org/abs/2502.01883 |