The effect of viscoelasticity in an airway closure model

Romanò, Francesco; Muradoğlu, Metin; Fujioka, Hideki; Grotberg, James B.

doi:10.1017/jfm.2020.1162

Cited by 18 publications

(17 citation statements)

References 74 publications

(215 reference statements)

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“…(2019) used a volume-of-fluid method to model the pre- and post-coalescence phases of Newtonian plug formation, and recently extended this work to include the effect of viscoelasticity (Romanò et al. 2021). They found that post-coalescence bi-frontal plug growth can induce significant stresses on the tube wall, and that viscoelasticity can induce additional wall stress due to the occurrence of an elastic instability.…”

Section: Introductionmentioning

confidence: 99%

Surface-tension-driven evolution of a viscoplastic liquid coating the interior of a cylindrical tube

et al. 2022

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One mechanism for airway closure in the lung is the surface-tension-driven instability of the mucus layer which lines the airway wall. We study the instability of an axisymmetric layer of viscoplastic Bingham liquid coating the interior of a rigid tube, which is a simple model for an airway that takes into account the yield stress of mucus. An evolution equation for the thickness of the liquid layer is derived using long-wave theory, from which we also derive a simpler thin-film evolution equation. In the thin-film case we show that two branches of marginally yielded static solutions of the evolution equation can be used to both predict the size of the initial perturbation required to trigger instability and quantify how increasing the capillary Bingham number (a parameter measuring yield stress relative to surface tension) reduces the final deformation of the layer. Using numerical solutions of the long-wave evolution equation, we quantify how the critical layer thickness required to form a liquid plug in the tube increases as the capillary Bingham number is increased. We discuss the significance of these findings for modelling airway closure in obstructive conditions such as cystic fibrosis, where the mucus layer is often thicker and has a higher yield stress.

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Section: Introductionmentioning

confidence: 99%

Surface-tension-driven evolution of a viscoplastic liquid coating the interior of a cylindrical tube

et al. 2022

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“…2 Considering a significant relevance in the wide range of applications, many scholars have investigated the flows in multiple geometries. 3–25…”

Section: Introductionmentioning

confidence: 99%

Impact of partial slip and lateral walls on peristaltic transport of a couple stress fluid in a rectangular duct

et al. 2021

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The impact of lateral walls and partial slip with different waveforms on peristaltic pumping of couple stress fluid in a rectangular duct with different waveforms has been discussed in the current article. By means of a wave frame of reference the flow is explored travelling away from a fixed frame with velocity c. Peristaltic waves generated on horizontal surface walls of rectangular duct are considered using lubrication technique. Mathematical modelling of couple fluid for three-dimensional flow are first discussed in detail. Lubrication approaches are used to simplify the proposed problem. Exact solutions of pressure gradient, pressure rise, velocity and stream function have been calculated. Numerical and graphical descriptions are displayed to look at the behaviour of diverse emerging parameters.

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“…The airways in the LRT of the adult lung has approximately 23 generations of bifurcations with the trachea being the zeroth generation and the terminal bronchioles number 23. In the LRT, the ASL has two distinct layers depending on the generation: (i) a complex hydrogel mucus layer that is directly exposed to the inhaled/exhaled air and acts as a clearance vehicle and protective barrier against foreign particles and pathogens (up to generation [15][16], and (ii) a periciliary fluid-like layer in which the cilia beat and which up to generation 15-16 is below the first layer (for generation >17 only the periciliary fluid-like layer remains) [e.g., see 33,34]. The primary component of the overall ASL in healthy humans is water, with a nonvolatile solid fraction of approximately 1.1-2.3% wt [35,36].…”

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confidence: 99%

Exhaled particles from nanometre to millimetre and their origin in the human respiratory tract

Bagheri

Schlenczek

Turco

et al. 2021

Preprint

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Detailed knowledge of the properties of exhaled particles from the human respiratory tract for all genders and ages is essential to determine the modes of transmission of airborne diseases. This applies not only to the current COVID-19 pandemic, but also to many others, be it measles, seasonal influenza or tuberculosis. To date, there are no data on the individual-specific concentrations and sizes of exhaled particles over the entire size range from nanometre to millimetre. Here we present a comprehensive data set, measured by particle size spectrometry and in-line holography covering the entire size range from 132 healthy volunteers aged 5 to 80 years for a defined set of breathing and vocalisation activities. We find age to have a large effect on small particle concentrations (<5 microns), doubling in children during adolescence and in adults over a 30-year period. In contrast, gender, body mass index, smoking or exercise habits have no discernible influence. Particles >20 microns show on average no measurable dependence on the type of vocalisation with the exception of shouting. We show evidence that particles <5 microns mainly originate in the lower respiratory tract, 5-15 microns in the larynx/pharynx, and >15 microns in the oral cavity.

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The effect of viscoelasticity in an airway closure model

Abstract: Abstract

Cited by 18 publications

References 74 publications

Surface-tension-driven evolution of a viscoplastic liquid coating the interior of a cylindrical tube

Surface-tension-driven evolution of a viscoplastic liquid coating the interior of a cylindrical tube

Impact of partial slip and lateral walls on peristaltic transport of a couple stress fluid in a rectangular duct

Exhaled particles from nanometre to millimetre and their origin in the human respiratory tract

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