A numerical model of an expanding asymmetric alveolated duct was developed and used to investigate lateral transport between the central acinar channel and the surrounding alveoli along the acinar tree. Our results indicate that some degree of recirculation occurs in all but the terminal generations. We found that the rate of diffusional transport of axial momentum from the duct to the alveolus was by far the largest contributor to the resulting momentum in the alveolar flow but that the magnitude of the axial momentum is critical in determining the nature of the flow in the alveolus. Further, we found that alveolar flow rotation, and by implication chaotic mixing, is strongest in the entrance generations. We also found that the expanding alveolus provides a pathway by which particles with little intrinsic motion can enter the alveoli. Thus, our results offer a possible explanation for why submicron particles deposit preferentially in the acinar-entrance region.

1.
Tsuda
,
A.
,
Henry
,
F. S.
, and
Butler
,
J. P.
, 1995, “
Chaotic Mixing of Alveolated Duct Flow in Rhythmically Expanding Pulmonary Acinus
,”
J. Appl. Physiol.
0021-8987,
79
(
3
), pp.
1055
1063
.
2.
Tsuda
,
A.
,
Henry
,
F. S.
, and
Butler
,
J. P.
, 2008, “
Gas and Aerosol Mixing in the Acinus
,”
Respir. Physiol. Neurbiol.
1569-9048,
163
, pp.
139
149
.
3.
Tsuda
,
A.
,
Rogers
,
R. A.
,
Hydon
,
P. E.
, and
Butler
,
J. P.
, 2002, “
Chaotic Mixing Deep in the Lung
,”
Proc. Natl. Acad. Sci. U.S.A.
0027-8424,
99
, pp.
10173
10178
.
4.
Henry
,
F. S.
,
Butler
,
J. P.
, and
Tsuda
,
A.
, 2002, “
Kinematically Irreversible Flow and Aerosol Transport in the Pulmonary Acinus: A Departure From Classical Dispersive Transport
,”
J. Appl. Physiol.
0021-8987,
92
, pp.
835
845
.
5.
Henry
,
F. S.
,
Laine-Pearson
,
F. E.
, and
Tsuda
,
A.
, 2009, “
Hamiltonian Chaos in a Model Alveolus
,”
J. Biomech. Eng.
0148-0731,
131
(
1
), p.
011006
.
6.
Haber
,
S.
,
Butler
,
J. P.
,
Brenner
,
H.
,
Emanuel
,
I.
, and
Tsuda
,
A.
, 2000, “
Flow Field in Self-Similar Expansion on a Pulmonary Alveolus During Rhythmical Breathing
,”
J. Fluid Mech.
0022-1120,
405
, pp.
243
268
.
7.
Lee
,
D. Y.
, and
Lee
,
J. W.
, 2003, “
Characteristics of Particle Transport in an Expanding or Contracting Alveolated Tube
,”
J. Aerosp. Sci.
0095-9820,
34
, pp.
1193
1215
.
8.
Sznitman
,
J.
,
Heimsch
,
F.
,
Heimsch
,
T.
,
Rusch
,
D.
, and
Roesgen
,
T.
, 2007, “
Three-Dimensional Convective Alveolar Flow Induced by Rhythmic Breathing Motion of the Pulmonary Acinus
,”
J. Biomech. Eng.
0148-0731,
129
, pp.
658
665
.
9.
Darquenne
,
C.
,
Harrington
,
L.
, and
Prisk
,
G. K.
, 2009, “
Alveolar Duct Expansion Greatly Enhances Aerosol Deposition: A Three-Dimensional Computational Fluid Dynamics Study
,”
Philos. Trans. R. Soc. London, Ser. A
0962-8428,
367
, pp.
2333
2346
10.
Kumar
,
H.
,
Tawhai
,
M. H.
,
Hoffman
,
E. A.
, and
Lin
,
C. -L.
, 2009, “
The Effects of Geometry on Airflow in the Acinar Region of the Human Lung
,”
J. Biomech.
0021-9290,
42
(
11
), pp.
1635
1642
.
11.
Haefeli-Bleuer
,
B.
, and
Weibel
,
E. R.
, 1988, “
Morphometry of the Human Pulmonary Acinus
,”
Anat. Rec.
0003-276X,
220
(
4
), pp.
401
414
.
12.
Weibel
,
E. R.
, 1984,
The Pathway for Oxygen-Structure and Function in the Mammalian Respiratory System
,
Harvard Univesity Press
,
Cambridge, MA
.
13.
Press
,
W. H.
,
Teukolsky
,
S. A.
,
Vetterling
,
W. T.
, and
Flannery
,
B. P.
, 1992,
Numerical Recipes in FORTRAN: The Art of Scientific Computing
,
2nd ed.
,
Cambridge University Press
,
Cambridge. UK
, p.
118
.
14.
Uchida
,
S.
, and
Aoki
,
H.
, 1977, “
Unsteady Flows in a Semi-Infinite Contracting or Expanding Pipe
,”
J. Fluid Mech.
0022-1120,
82
, pp.
371
387
.
15.
Pinkerton
,
K. E.
,
Green
,
F. H.
,
Saiki
,
C.
,
Vallyathan
,
V.
,
Plopper
,
C. G.
,
Gopal
,
V.
,
Hung
,
D.
,
Bahne
,
E. B.
,
Lin
,
S. S.
,
Ménache
,
M. G.
, and
Schenker
,
M. B.
, 2000, “
Distribution of Particulate Matter and Tissue Remodeling in the Human Lung
,”
Environ. Health Perspect.
0091-6765,
108
(
11
), pp.
1063
1069
.
16.
Saldiva
,
P. H.
,
Clarke
,
R. W.
,
Coull
,
B. A.
,
Stearns
,
R. C.
,
Lawrence
,
J.
,
Murthy
,
G. G.
,
Diaz
,
E.
,
Koutrakis
,
P.
,
Suh
,
H.
,
Tsuda
,
A.
, and
Godleski
,
J. J.
, 2002, “
Lung Inflammation Induced by Concentrated Ambient Air Particles is Related to Particle Composition
,”
Am. J. Respir. Crit. Care Med.
1073-449X,
165
(
12
), pp.
1610
1617
.
17.
Churg
,
A.
, and
Brauer
,
M.
, 2000, “
Ambient Atmospheric Particles in the Airways of Human Lungs
,”
Ultrastruct. Pathol.
0191-3123,
24
(
6
), pp.
353
361
.
18.
Kitaoka
,
H.
,
Nieman
,
G. F.
,
Fujino
,
Y.
,
Carney
,
D.
,
DiRocco
,
J.
, and
Kawase
,
I.
, 2007, “
A 4-Dimensional Model of the Alveolar Structure
,”
J. Physiol. Sci.
1880-6546,
57
(
3
), pp.
175
185
.
19.
Batchelor
,
G. K.
, 1967,
An Introduction to Fluid Dynamics
,
Cambridge University Press
,
London, UK
.
20.
Ferziger
,
J. H.
, and
Perić
,
M.
, 1997,
Computational Methods for Fluid Dynamics
,
Springer-Verlag
,
Berlin
.
21.
Muzaferija
,
S.
, 1994, “
Adaptive Finite Element Volume Method for Flow Predictions Using Unstructured Meshes and Multigrid Approach
,” Ph.D. thesis, University of London, London.
22.
Demirdžić
,
I.
, and
Perić
,
M.
, 1988, “
Space Conservation Law in Finite Volume Calculations of Fluid Flow
,”
Int. J. Numer. Methods Fluids
0271-2091,
8
, pp.
1037
1050
.
23.
Roache
,
P. J.
, 1976,
Computational Fluid Dynamics
,
Hermosa
,
Albuquerque, NM
.
24.
Gehr
,
P.
,
Bachofen
,
M.
, and
Weibel
,
E. R.
, 1978, “
The Normal Human Lung: Ultrastructure and Morphometric Estimation of Diffusion Capacity
,”
Respir. Physiol.
0034-5687,
32
, pp.
121
140
.
You do not currently have access to this content.