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.
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December 2012
Research-Article
The Simultaneous Role of an Alveolus as Flow Mixer and Flow Feeder for the Deposition of Inhaled Submicron Particles
F. S. Henry,
F. S. Henry
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
Department of Environmental Health,
Harvard School of Public Health
,Boston, MA 02115
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S. Haber,
S. Haber
Faculty of Mechanical Engineering,
Technion-Israel Institute of Technology
,Haifa
, Israel
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D. Haberthür,
D. Haberthür
Swiss Light Source,
Villigen,
Paul Scherrer Institut
,Villigen,
Switzerland
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N. Filipovic,
N. Filipovic
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
Harvard School of Public Health,
Boston, MA 02115;
Faculty of Mechanical Engineering,
Department of Environmental Health,
Harvard School of Public Health,
Boston, MA 02115;
Faculty of Mechanical Engineering,
University of Kragujevac
, Serbia
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D. Milasinovic,
D. Milasinovic
Faculty of Mechanical Engineering,
University of Kragujevac
, Serbia
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J. C. Schittny,
J. C. Schittny
Institute of Anatomy,
University of Bern
Bern
, Switzerland
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A. Tsuda
A. Tsuda
1
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
e-mail: atsuda@hsph.harvard.edu
Department of Environmental Health,
Harvard School of Public Health
,Boston, MA 02115
e-mail: atsuda@hsph.harvard.edu
1Corresponding author.
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F. S. Henry
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
Department of Environmental Health,
Harvard School of Public Health
,Boston, MA 02115
S. Haber
Faculty of Mechanical Engineering,
Technion-Israel Institute of Technology
,Haifa
, Israel
D. Haberthür
Swiss Light Source,
Villigen,
Paul Scherrer Institut
,Villigen,
Switzerland
N. Filipovic
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
Harvard School of Public Health,
Boston, MA 02115;
Faculty of Mechanical Engineering,
Department of Environmental Health,
Harvard School of Public Health,
Boston, MA 02115;
Faculty of Mechanical Engineering,
University of Kragujevac
, Serbia
D. Milasinovic
Faculty of Mechanical Engineering,
University of Kragujevac
, Serbia
J. C. Schittny
Institute of Anatomy,
University of Bern
Bern
, Switzerland
A. Tsuda
Molecular and Integrative Physiological Sciences,
Department of Environmental Health,
e-mail: atsuda@hsph.harvard.edu
Department of Environmental Health,
Harvard School of Public Health
,Boston, MA 02115
e-mail: atsuda@hsph.harvard.edu
1Corresponding author.
Contributed by the Bioengineering Division of ASME for publication in the JOURNAL OF BIOMECHANICAL ENGINEERING. Manuscript received February 27, 2012; final manuscript received October 13, 2012; accepted manuscript posted October 25, 2012; published online November 27, 2012. Assoc. Editor: Dalin Tang.
J Biomech Eng. Dec 2012, 134(12): 121001 (11 pages)
Published Online: November 27, 2012
Article history
Received:
February 27, 2012
Revision Received:
October 13, 2012
Accepted:
October 25, 2012
Citation
Henry, F. S., Haber, S., Haberthür, D., Filipovic, N., Milasinovic, D., Schittny, J. C., and Tsuda, A. (November 27, 2012). "The Simultaneous Role of an Alveolus as Flow Mixer and Flow Feeder for the Deposition of Inhaled Submicron Particles." ASME. J Biomech Eng. December 2012; 134(12): 121001. https://doi.org/10.1115/1.4007949
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