Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

Haribalan Kumar; Merryn H Tawhai; Eric A Hoffman; Ching-Long Lin

doi:10.1063/1.3567066

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Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

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Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

Haribalan Kumar, Merryn H Tawhai, Eric A Hoffman and Ching-Long Lin

Physics of fluids (1994), Vol.23(4), pp.041902-041902-21

04/2011

DOI: 10.1063/1.3567066

PMCID: PMC3094461

PMID: 21580803

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Abstract

Study of mixing is important in understanding transport of submicron sized particles in the acinar region of the lung. In this article, we investigate transport in view of advective mixing utilizing Lagrangian particle tracking techniques: tracer advection, stretch rate and dispersion analysis. The phenomenon of steady streaming in an oscillatory flow is found to hold the key to the origin of kinematic mixing in the alveolus, the alveolar mouth and the alveolated duct. This mechanism provides the common route to folding of material lines and surfaces in any region of the acinar flow, and has no bearing on whether the geometry is expanding or if flow separates within the cavity or not. All analyses consistently indicate a significant decrease in mixing with decreasing Reynolds number (Re). For a given Re, dispersion is found to increase with degree of alveolation, indicating that geometry effects are important. These effects of Re and geometry can also be explained by the streaming mechanism. Based on flow conditions and resultant convective mixing measures, we conclude that significant convective mixing in the duct and within an alveolus could originate only in the first few generations of the acinar tree as a result of nonzero inertia, flow asymmetry, and large Keulegan–Carpenter ( K C ) number.

Biofluid Mechanics

Details

Title: Subtitle: Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows
Creators: Haribalan Kumar - Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa 52242, USA and IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa 52242, USA
Merryn H Tawhai - Bioengineering Institute, The University of Auckland, Auckland 1010, New Zealand
Eric A Hoffman - Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa 52242, USA; Department of Internal Medicine, The University of Iowa, Iowa City, Iowa 52242, USA; and Department of Radiology, The University of Iowa, Iowa City, Iowa 52242, USA
Ching-Long Lin - Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa 52242, USA and IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa 52242, USA
Resource Type: Journal article
Publication Details: Physics of fluids (1994), Vol.23(4), pp.041902-041902-21
Publisher: American Institute of Physics
DOI: 10.1063/1.3567066
PMID: 21580803
PMCID: PMC3094461
ISSN: 1070-6631
eISSN: 1089-7666
Grant note: DOI: 10.13039/100000002, name: National Institutes of Health, award: R01-EB-005823, R01-HL-064368, R01-HL-094315, S10-RR-022421
Language: English
Date published: 04/2011
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Radiology; Mechanical Engineering; Internal Medicine
Record Identifier: 9984051742802771

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