Ring waves as a mass transport mechanism in air-driven core-annular flows

Camassa, Roberto; Forest, M. Gregory; Lee, Long; Ogrosky, H. Reed; Olander, Jeffrey

doi:10.1103/physreve.86.066305

Cited by 24 publications

(58 citation statements)

References 20 publications

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“…Camassa et al [90] studied, experimentally and theoretically, flows where an annular viscous liquid film lining the wall of a tube is forced upwards against gravity by turbulent airflow up the core of the tube. This core-annular flow configurations mimics mucus clearance in the trachea and was pursued to reproduce and extend seminal experiments by Kim et al [91,142,143].…”

Section: Cough Clearancementioning

confidence: 99%

“…2.6. To prevent infection or [89] inflammation, airway mucus must be cleared by a combination of coordinated cilia and airdrag; clearance requires a balance between the rheological properties of the mucus, PCL properties and volume, ciliary beat frequency and cilium length [32], and air-liquid transport [90,91]. The PCL in healthy conditions is ∼ 7 μm thick [92,93].…”

Section: Mucociliary Clearancementioning

confidence: 99%

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Complex Fluids and Soft Structures in the Human Body

Vasquez¹,

Forest²

2014

Complex Fluids in Biological Systems

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The human body is a composite of diverse materials able to perform specific functions. Few of these materials are simple liquids or solids; rather they share both liquid-like and solid-like properties. The material world between liquids and solids is unlimited and exploited by Nature to form complex fluids and soft structures with properties that are tuned to perform highly specialized functions. This chapter will briefly summarize the diversity of materials in the human body, and then drill deeper into one complex fluid (mucus, which coats every organ in the body) and one soft structure (an individual cell), and their remarkable properties. Some progress in characterizing these materials and modeling their functional properties, by others and our research group, will be presented with the take home message that we are in the early stages of interpreting experimental data and building predictive models and simulations of biological materials.

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Section: Cough Clearancementioning

confidence: 99%

Section: Mucociliary Clearancementioning

confidence: 99%

Complex Fluids and Soft Structures in the Human Body

Vasquez¹,

Forest²

2014

Complex Fluids in Biological Systems

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“…The most critical difference between the film dynamics of the exterior and the interior coating flow is that for the interior case the film may form occlusive liquid plugs in the tube. Camassa et al [15] studied, both experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upward against gravity by turbulent air flow up the center of the tube. Ring waves were identified as a mass transport mechanism in air-driven core-annular flows.…”

Section: Introductionmentioning

confidence: 99%

Stability of viscous film flow coating the interior of a vertical tube with a porous wall

Liu

Ding

2017

Phys. Rev. E

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This is the final published version of the article (version of record). It first appeared online via APS Physics at https://doi.org/10.1103/PhysRevE.95.053101 . Please refer to any applicable terms of use of the publisher. University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms PHYSICAL REVIEW E 95, 053101 (2017) The stability of the gravity-driven flow of a viscous film coating the inside of a tube with a porous wall is studied theoretically. We used Darcy's law to describe the motion of fluids in a porous medium. The Beaver-Joseph condition is used to describe the discontinuity of velocity at the porous-fluid interface. We derived an evolution equation for the film thickness using a long-wave approximation. The effect of velocity slip at the porous wall is identified by a parameter β. We examine the effect of β on the temporal stability, the absolute-convective instability (AI-CI), and the nonlinear evolution of the interface deformation. The results of the temporal stability reveal that the effect of velocity slip at the porous wall is destabilizing. The parameter β plays an important role in determining the AI-CI behavior and the nonlinear evolution of the interface. The presence of the porous wall promotes the absolute instability and the formation of the plug in the tube. Stability of viscous film flow coating the interior of a vertical tube with a porous wall

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“…According to some of the earlier studies (Shearer & Davidson 1965;Cetinbudaklar & Jameson 1969), the flooding point corresponds to the critical gas flow rate where a standing wave is formed on the interface, whose amplitude is much larger than the mean film thickness. We further propose that this critical gas flow rate indeed has a close correspondence with the onset of absolute instability in the system.…”

Section: Introductionmentioning

confidence: 99%

“…density stratification and orientation, curvature of the velocity profile, viscosity stratification, shear effects or a combination of the last two. Camassa et al (2012) performed experiments on a vertical core-annular flow system, where a thin liquid film lining the inside of a circular tube is driven by a counter-current turbulent air flow. They also compared their experimental results with a simple long-wave model.…”

Section: Introductionmentioning

confidence: 99%

Absolute and convective instabilities in counter-current gas–liquid film flows

2014

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Absolute and convective instabilities in counter-current gas-liquid film flows. Mechanics, 763, Additional Information: Journal of Fluid• This is the accepted manuscript of an article subsequently published in We consider a thin liquid film flowing down an inclined plate in the presence of a countercurrent turbulent gas. By making appropriate assumptions, Tseluiko & Kalliadasis (2011) developed low-dimensional non-local models for the liquid problem, namely a long-wave model and a weighted integral-boundary-layer model, that incorporate the effect of the turbulent gas. By utilising these models, along with the Orr-Sommerfeld problem formulated using the full governing equations for the liquid phase and associated boundary conditions, we explore the linear stability of the gas-liquid system. In addition, we devise a generalised methodology to investigate absolute and convective instabilities in the nonlocal equations describing the gas-liquid flow. We observe that at low gas flow rates, the system is convectively unstable with the localised disturbances being convected downwards. As the gas flow rate is increased, the instability becomes absolute and localised disturbances spread across the whole domain. As the gas flow rate is further increased, the system again becomes convectively unstable with the localised disturbances propagating upwards. We find that the upper limit of the absolute instability region is close to the 'flooding' point associated with the appearance of large-amplitude standing waves, as obtained in Tseluiko & Kalliadasis (2011), and our analysis can therefore be used to predict the onset of flooding. We also find that an increase in the angle of inclination of the channel requires an increased gas flow rate for the onset of absolute instability. We generally find good agreement between the results obtained using the full equations and the reduced models. Moreover, we find that the weighted integral-boundary-layer model generally provides better agreement with the results for the full equations than the longwave model. Such an analysis is important for understanding the ranges of validity of the reduced model equations. In addition, a comparison of our theoretical predictions with the experiments of Zapke & Kröger (2000a) shows a fairly good agreement. We supplement our stability analysis with time-dependent computations of the linearised weighted integral-boundary-layer model. To provide some insight into the mechanisms of instability, we perform an energy budget analysis.

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Ring waves as a mass transport mechanism in air-driven core-annular flows

Cited by 24 publications

References 20 publications

Complex Fluids and Soft Structures in the Human Body

Complex Fluids and Soft Structures in the Human Body

Stability of viscous film flow coating the interior of a vertical tube with a porous wall

Absolute and convective instabilities in counter-current gas–liquid film flows

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