Characteristics of particle transport in an expanding or contracting alveolated tube

Abstract Features of flow and particle transport in a single axisymmetric alveolated tube with 30 cells in the presence of wall motion are analyzed numerically for flow conditions typically found in the Aerosol Bolus experiments: the tracheal breathing flowrate of 250 ml / s and breathing period of 8 s . Different characteristics of particle transport between the alveolated and the straight tube are explained based on the details of flow and particle motion. For both expansion and contraction the axial motion of particles in an alveolated tube is smaller than in a straight tube due to the decelerated flow in the alveolated region. In an expanding alveolated tube particles get accumulated near the wall and some particles enter alveolus, which make dispersion larger than that in an expanding straight tube. In a contracting alveolated tube particles consistently move toward the tube center, and flow velocity profile is much blunter than the parabolic one, making dispersion smaller than in a contracting straight tube. In the presence of wall motion, the difference in particle transport between alveolated tube and straight tube becomes larger as Strouhal number is increased. Limitations and physiological implications of the results are discussed.

[1]  Hiroshi Aoki,et al.  Unsteady flows in a semi-infinite contracting or expanding pipe , 1977, Journal of Fluid Mechanics.

[2]  Anthony S. Wexler,et al.  Modeling aerosol bolus dispersion in human airways , 1999 .

[3]  E. Weibel,et al.  Morphological study of pressure-volume hysteresis in rat lungs fixed by vascular perfusion. , 1972, Respiration physiology.

[4]  J J Fredberg,et al.  Axial dispersion in respiratory bronchioles and alveolar ducts. , 1988, Journal of applied physiology.

[5]  H. Brenner,et al.  Shear flow over a self-similar expanding pulmonary alveolus during rhythmical breathing , 2000, Journal of Fluid Mechanics.

[6]  Roger D. Kamm,et al.  Numerical studies of steady flow dispersion at low Dean number in a gently curving tube , 1986, Journal of Fluid Mechanics.

[7]  Engel La,et al.  Gas Mixing and Distribution in the Lung , 1985 .

[8]  R. S. Deelder,et al.  Measurement of axial dispersion in laminar flow through coiled capillary tubes , 1979 .

[9]  Jin W. Lee,et al.  DISPERSION OF AN AEROSOL BOLUS IN A DOUBLE BIFURCATION , 2000 .

[10]  F. S. Henry,et al.  Chaotic mixing of alveolated duct flow in rhythmically expanding pulmonary acinus. , 1995, Journal of applied physiology.

[11]  Chantal Darquenne,et al.  Heterogeneity of aerosol deposition in a two-dimensional model of human alveolated ducts , 2002 .

[12]  N. M. Greene,et al.  Measurement of axial diffusivities in a model of the bronchial airways. , 1975, Journal of applied physiology.

[13]  M. Dolovich,et al.  Aerosols as diagnostic tools. , 1994, Journal of aerosol medicine : the official journal of the International Society for Aerosols in Medicine.

[14]  C. P. Yu.  On equation of gas transport in the lung. , 1975, Respiration physiology.

[15]  Jeffrey J. Fredberg,et al.  Axial dispersion of inert species in alveolated channels , 1991 .

[16]  J. Heyder,et al.  Aerosol dispersion in human lung: comparison between numerical simulations and experiments for bolus tests. , 1997, Journal of applied physiology.

[17]  A. Wexler,et al.  The role of dispersion in particle deposition in human airways. , 2000, Toxicological sciences : an official journal of the Society of Toxicology.

[18]  J. Butler,et al.  Effect of convective stretching and folding on aerosol mixing deep in the lung, assessed by approximate entropy. , 1997, Journal of applied physiology.

[19]  Jin W. Lee,et al.  Dispersion of aerosol bolus during one respiration cycle in a model of lung airways , 2002 .

[20]  Jin W. Lee,et al.  Dispersion during exhalation of an aerosol bolus in a double bifurcation , 2001 .

[21]  P. C. Chatwin,et al.  The effects of curvature and buoyancy on the laminar dispersion of solute in a horizontal tube , 1967, Journal of Fluid Mechanics.

[22]  D. Edwards.  A general theory of the macrotransport of nondepositing particles in the lung by convective dispersion , 1994 .

[23]  J. Hildebrandt,et al.  Macroscopic isotropy of lung expansion. , 1974, Respiration physiology.

[24]  E. Weibel.  Morphometry of the Human Lung , 1965, Springer Berlin Heidelberg.

[25]  E. Weibel,et al.  Alveolar volume-surface area relation in air- and saline-filled lungs fixed by vascular perfusion. , 1979, Journal of applied physiology: respiratory, environmental and exercise physiology.

[26]  R. Sankarasubramanian,et al.  Exact analysis of unsteady convective diffusion , 1970, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[27]  J. Fredberg,et al.  Effects of alveolated duct structure on aerosol kinetics. II. Gravitational sedimentation and inertial impaction. , 1994, Journal of applied physiology.

[28]  J J Fredberg,et al.  Effects of alveolated duct structure on aerosol kinetics. I. Diffusional deposition in the absence of gravity. , 1994, Journal of applied physiology.

[29]  Akira Tsuda,et al.  RECIRCULATING FLOW IN AN EXPANDING ALVEOLAR MODEL: EXPERIMENTAL EVIDENCE OF FLOW-INDUCED MIXING OF AEROSOLS IN THE PULMONARY ACINUS , 2000 .

[30]  M. Paiva,et al.  One-dimensional simulation of aerosol transport and deposition in the human lung. , 1994, Journal of applied physiology.

[31]  Chantal Darquenne,et al.  A realistic two-dimensional model of aerosol transport and deposition in the alveolar zone of the human lung , 2001 .

[32]  J. Butler,et al.  Geometric hysteresis in pulmonary surface-to-volume ratio during tidal breathing. , 1993, Journal of applied physiology.

[33]  W. Gill,et al.  Laminar dispersion in curved tubes and channels , 1972, Journal of Fluid Mechanics.

[34]  W. Hofmann,et al.  Monte Carlo modeling of aerosol deposition in human lungs. Part I: Simulation of particle transport in a stochastic lung structure , 1990 .

[35]  G. Taylor.  Dispersion of soluble matter in solvent flowing slowly through a tube , 1953, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[36]  B. Andersson,et al.  Dispersion in laminar flow through a circular tube , 1981, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[37]  D. Taulbee,et al.  A theory of aerosol deposition in the human respiratory tract. , 1975, Journal of applied physiology.