An understanding of flow and dispersion in the human respiratory airways is necessary to assess the toxicological impact of inhaled particulate matter as well as to optimize the design of inhalable pharmaceutical aerosols and their delivery systems. Secondary flows affect dispersion in the lung by mixing solute in the lumen cross section. The goal of this study is to measure and interpret these secondary velocity fields using in vitro lung models. Particle image velocimetry experiments were conducted in a three-generational, anatomically accurate model of the conducting region of the lung. Inspiration and expiration flows were examined under steady and oscillatory flow conditions. Results illustrate secondary flow fields as a function of flow direction, Reynolds number, axial location with respect to the bifurcation junction, generation, branch, phase in the oscillatory cycle, and Womersley number. Critical Dean number for the formation of secondary vortices in the airways, as well as the strength and development length of secondary flow, is characterized. The normalized secondary velocity magnitude was similar on inspiration and expiration and did not vary appreciably with generation or branch. Oscillatory flow fields were not significantly different from corresponding steady flow fields up to a Womersley number of 1 and no instabilities related to shear were detected on flow reversal. These observations were qualitatively interpreted with respect to the simple streaming, augmented dispersion, and steady streaming convective dispersion mechanisms.

1.
Drazen
,
J. M.
,
Kamm
,
R. D.
, and
Slutsky
,
A. S.
, 1984, “
High-Frequency Ventilation
,”
Physiol. Rev.
0031-9333,
64
(
2
), pp.
505
543
.
2.
Kohlhaufl
,
M.
,
Brand
,
P.
,
Selzer
,
T.
,
Scheuch
,
G.
,
Meyer
,
T.
,
Weber
,
N.
,
Schulz
,
H.
,
Haussinger
,
K.
, and
Heyder
,
J.
, 1998, “
Diagnosis of Emphysema in Patients With Chronic Bronchitis: A New Approach
,”
Eur. Respir. J.
0903-1936,
12
, pp.
793
798
.
3.
Edwards
,
D. A.
, and
Dunbar
,
C.
, 2002, “
Bioengineering of Therapeutic Aerosols
,”
Annu. Rev. Biomed. Eng.
1523-9829,
4
, pp.
93
107
.
4.
Robinson
,
R. J.
, and
Yu
,
C. P.
, 2001, “
Deposition of Cigarette Smoke Particles in the Human Respiratory Tract
,”
Aerosol Sci. Technol.
0278-6826,
34
, pp.
202
215
.
5.
Schwartz
,
J.
, and
Dockery
,
D. W.
, 1992, “
Increased Mortality in Philadelphia Associated With Daily air Pollution Concentrations
,”
Am. Rev. Respir. Dis.
0003-0805,
145
, pp.
600
604
.
6.
Edwards
,
D. A.
,
Man
,
J. C.
,
Brand
,
P.
,
Katstra
,
J. P.
,
Sommerer
,
K.
,
Stone
,
H. A.
,
Nardell
,
E.
, and
Scheuch
,
G.
, 2004, “
Inhaling to Mitigate Exhaled Bioaerosols
,”
Proc. Natl. Acad. Sci. U.S.A.
0027-8424,
101
(
50
), pp.
17383
17388
.
7.
Heyder
,
J.
,
Blanchard
,
J. D.
,
Feldman
,
H. A.
, and
Brain
,
J. D.
, 1988, “
Convective Mixing in Human Respiratory Tract: Estimates With Aerosol Boli
,”
J. Appl. Physiol.
8750-7587,
64
(
3
), pp.
1273
1278
.
8.
Haselton
,
F. R.
, and
Scherer
,
P. W.
, 1980, “
Bronchial Bifurcations and Respiratory Mass Transport
,”
Science
0036-8075,
208
(
4439
), pp.
69
71
.
9.
Haselton
,
F. R.
, and
Scherer
,
P. W.
, 1982, “
Flow Visualization of Steady Streaming in Oscillatory Flow Through a Bifurcating Tube
,”
J. Fluid Mech.
0022-1120,
123
, pp.
315
333
.
10.
Scherer
,
P. W.
, and
Haselton
,
F. R.
, 1982, “
Convective Exchange in Oscillatory Flow Through Bronchial-tree Models
,”
J. Appl. Physiol.: Respir., Environ. Exercise Physiol.
0161-7567,
53
(
4
), pp.
1023
1033
.
11.
Taylor
,
G. I.
, 1953, “
Dispersion of Soluble Matter in Solvent Flowing Slowly Through a Tube
,”
Proc. R. Soc. London, Ser. A
1364-5021,
219
, pp.
186
203
.
12.
Taylor
,
G. I.
, 1954, “
The Dispersion of Matter in Turbulent Flow Through a Pipe
,”
Proc. R. Soc. London, Ser. A
1364-5021,
223
, pp.
446
468
.
13.
Aris
,
R.
, 1956, “
On the Dispersion of Solute in a Fluid Flowing Through a Tube
,”
Proc. R. Soc. London, Ser. A
1364-5021,
235
, pp.
66
77
.
14.
Chang
,
H. K.
, 1976, “
Effect of Taylor Dispersion on Stratified Inhomogeneity (Abstract)
,”
Physiologist
0031-9376,
19
, p.
151
.
15.
Horsfield
,
K.
,
Davies
,
A.
, and
Cumming
,
G.
, 1977, “
Role of Conducting Airways in Partial Separation of Inhaled Gas Mixtures
,”
J. Appl. Physiol.: Respir., Environ. Exercise Physiol.
0161-7567,
43
(
3
), pp.
391
396
.
16.
Fredberg
,
J. J.
, 1980, “
Augmented Diffusion in the Airways Can Support Pulmonary Gas Exchange
,”
J. Appl. Physiol.: Respir., Environ. Exercise Physiol.
0161-7567,
49
(
2
), pp.
232
238
.
17.
Scherer
,
P. W.
,
Shendalman
,
L. H.
,
Greene
,
N. M.
, and
Bouhuys
,
A.
, 1975, “
Measurement of Axial Diffusivities in a Model of the Bronchial Airways
,”
J. Appl. Physiol.
0021-8987,
38
(
4
), pp.
719
723
.
18.
Kamm
,
R. D.
,
Collins
,
J.
,
Whang
,
J.
,
Slutsky
,
A. S.
, and
Greiner
,
M.
, 1984, “
Gas Transport During Oscillatory Flow in a Network of Branching Tubes
,”
J. Biomed. Eng.
0141-5425,
106
, pp.
315
320
.
19.
Tarbell
,
J. M.
,
Ultman
,
J. S.
, and
Durlofsky
,
L.
, 1982, “
Oscillatory Convective Dispersion in a Branching Tube Network
,”
J. Biomed. Eng.
0141-5425,
104
, pp.
338
342
.
20.
Permutt
,
S.
,
Mitzner
,
W.
, and
Weinmann
,
G.
, 1985, “
Model of Gas Transport During High-Frequency Ventilation
,”
J. Appl. Physiol.
8750-7587,
58
, pp.
1956
1970
.
21.
Paloski
,
W. H.
,
Slosberg
,
R. B.
, and
Kamm
,
R. D.
, 1987, “
Effects of Gas Properties and Waveform Asymmetry on Gas Transport in a Branching Tube Network
,”
J. Appl. Physiol.
8750-7587,
62
(
3
), pp.
892
901
.
22.
Pedley
,
T. J.
, and
Kamm
,
R. D.
, 1988, “
The Effect of Secondary Motion on Axial Transport in Oscillatory Tube Flow
,”
J. Fluid Mech.
0022-1120,
193
, pp.
347
367
.
23.
Jan
,
D. L.
,
Shapiro
,
A. H.
, and
Kamm
,
R. D.
, 1989, “
Some Features of Oscillatory Flow in a Model Bifurcation
,”
J. Appl. Physiol.
8750-7587,
67
(
1
), pp.
147
159
.
24.
Tanaka
,
G.
,
Ueda
,
Y.
, and
Tanishita
,
K.
, 1998, “
Augmentation of Axial Dispersion by Intermittent Oscillatory Flow
,”
ASME J. Biomech. Eng.
0148-0731,
120
, pp.
405
415
.
25.
Isabey
,
D.
, and
Chang
,
H. K.
, 1982, “
Model Study of Flow Dynamics in Human Central Airways. Part II: Secondary Flow Velocities
,”
Respir. Physiol.
0034-5687,
55
, pp.
255
275
.
26.
Zhao
,
Y.
, and
Lieber
,
B. B.
, 1994, “
Steady Inspiratory Flow in a Model Symmetric Bifurcation
,”
ASME J. Biomech. Eng.
0148-0731,
116
, pp.
488
496
.
27.
Zhao
,
Y.
, and
Lieber
,
B. B.
, 1994, “
Steady Expiratory Flow in a Model Symmetric Bifurcation
,”
ASME J. Biomech. Eng.
0148-0731,
116
, pp.
318
323
.
28.
Tanaka
,
G.
,
Ogata
,
T.
,
Oka
,
K.
, and
Tanishita
,
K.
, 1999, “
Spatial and Temporal Variation of Secondary Flow During Oscillatory Flow in Model Human Central Airways
,”
ASME J. Biomech. Eng.
0148-0731,
121
, pp.
565
573
.
29.
Farag
,
A.
,
Hammersley
,
J.
,
Olson
,
D.
, and
Ng
,
T.
, 2000, “
Mechanics of the Flow in the Small and Middle Human Airways
,”
ASME J. Biomech. Eng.
0148-0731,
122
, pp.
576
584
.
30.
Fresconi
,
F. E.
,
Wexler
,
A. S.
, and
Prasad
,
A. K.
, 2003, “
Expiration Flow in a Symmetric Bifurcation
,”
Exp. Fluids
0723-4864,
35
, pp.
493
501
.
31.
Dean
,
W. R.
, 1927, “
Note on the Motion of Fluid in a Curved Pipe
,”
Philos. Mag.
0031-8086,
4
(
7
), pp.
208
223
.
32.
Comer
,
J. K.
,
Kleinstreuer
,
C.
, and
Zhang
,
Z.
, 2001, “
Flow Structures and Particle Deposition Patterns in Double-Bifurcation Airway Models. Part 1. Air Flow Fields
,”
J. Fluid Mech.
0022-1120,
435
, pp.
25
54
.
33.
Zhang
,
Z.
, and
Kleinstreuer
,
C.
, 2002, “
Transient Airflow Structures and Particle Transport in a Sequentially Branching Lung Airway Model
,”
Phys. Fluids
1070-6631,
14
(
2
), pp.
862
880
.
34.
Godleski
,
D. A.
, and
Grotberg
,
J. B.
, 1988, “
Convection-Diffusion Interaction for Oscillatory Flow in a Tapered Tube
,”
ASME J. Biomech. Eng.
0148-0731,
110
, pp.
283
291
.
35.
Pedley
,
T. J.
, 1977, “
Pulmonary Fluid Dynamics
,”
Annu. Rev. Fluid Mech.
0066-4189,
9
, pp.
229
274
.
36.
Hopkins
,
L. M.
,
Kelly
,
J. T.
,
Wexler
,
A. S.
, and Prasad A. K., 2000, “
PIV Measurements in Complex Geometries
,”
Exp. Fluids
0723-4864,
29
(
1
), pp.
91
95
.
37.
Weibel
,
E. R.
, 1963,
Morphometry of the Lung
,
Springer-Verlag
,
Berlin
.
38.
Daskopoulos
,
P.
, and
Lenhoff
,
A. M.
, 1989, “
Flow in Curved Ducts: Bifurcation Structure for Stationary Ducts
,”
J. Fluid Mech.
0022-1120,
203
, pp.
125
148
.
39.
Berger
,
S. A.
,
Talbot
,
L.
, and
Yao
,
L. S.
, 1983, “
Flow in Curved Pipes
,”
Annu. Rev. Fluid Mech.
0066-4189,
15
, pp.
461
512
.
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