The simultaneous role of an alveolus as flow mixer and flow feeder for the deposition of inhaled submicron particles

Henry, F S; Haber, S; Haberthür, David; Filipovic, N; Milasinovic, D; Schittny, Johannes C.; Tsuda, A (2012). The simultaneous role of an alveolus as flow mixer and flow feeder for the deposition of inhaled submicron particles. Journal of biomechanical engineering, 134(12), p. 121001. New York, N.Y.: American Society of Mechanical Engineers ASME 10.1115/1.4007949

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In an effort to understand the fate of inhaled submicron particles in the small sacs, or alveoli, comprising the gas-exchange region of the lung, we calculated the flow in three-dimensional (3D) rhythmically expanding models of alveolated ducts. Since convection toward the alveolar walls is a precursor to particle deposition, it was the goal of this paper to investigate the streamline maps' dependence upon alveoli location along the acinar tree. On the alveolar midplane, the recirculating flow pattern exhibited closed streamlines with a stagnation saddle point. Off the midplane we found no closed streamlines but nested, funnel-like, spiral, structures (reminiscent of Russian nesting dolls) that were directed towards the expanding walls in inspiration, and away from the contracting walls in expiration. These nested, funnel-like, structures were surrounded by air that flowed into the cavity from the central channel over inspiration and flowed from the cavity to the central channel over expiration. We also found that fluid particle tracks exhibited similar nested funnel-like spiral structures. We conclude that these unique alveolar flow structures may be of importance in enhancing deposition. In addition, due to inertia, the nested, funnel-like, structures change shape and position slightly during a breathing cycle, resulting in flow mixing. Also, each inspiration feeds a fresh supply of particle-laden air from the central channel to the region surrounding the mixing region. Thus, this combination of flow mixer and flow feeder makes each individual alveolus an effective mixing unit, which is likely to play an important role in determining the overall efficiency of convective mixing in the acinus.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Functional Anatomy

UniBE Contributor:

Haberthür, David and Schittny, Johannes

ISSN:

0148-0731

Publisher:

American Society of Mechanical Engineers ASME

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:35

Last Modified:

20 Dec 2016 15:02

Publisher DOI:

10.1115/1.4007949

PubMed ID:

23363203

Web of Science ID:

000314033500001

URI:

https://boris.unibe.ch/id/eprint/14073 (FactScience: 220877)

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