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Airway Gas Flow

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Abstract

Local characteristics of airflow and its global distribution in the lung are determined by interaction between resistance to flow through the airways and the compliance of the tissue, with tissue compliance dominating flow distribution in the healthy lung. Current understanding is that conceptualizing the airways of the lung as a system of smooth adjoined cylinders through which air traverses laminarly is insufficient for understanding flow and energy dissipation and is particularly poor for predicting physiologically realistic transport of particles by the airflow. With rapid advances in medical imaging, computer technologies, and computational techniques, computational fluid dynamics is now becoming a viable tool for providing detailed information on the mechanics of airflow in the human respiratory tract. Studies using such techniques have shown that the upper airway (specifically its development of a turbulent laryngeal jet in the trachea), airway geometry, branching and rotation angle, and the pattern of joining of successive bifurcations are important in determining airflow structures. It is now possible to compute airflow in physical domains that are anatomically accurate and subject specific, enabling comparisons among intersubjects, that among subjects of different ages, and that among different species. © 2011 American Physiological Society. Compr Physiol 1:1135‐1157, 2011.

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Figure 1. Figure 1.

Flow regimes of the conducting airway categorized on the basis of a dimensionless frequency α2 (where α is the Womersley number) and a dimensionless stroke length L/a. The (I) unsteady, (II) viscous, and (IIIa, IIIb) convective flow regimes are classified according to Jan et al. .

Figure 2. Figure 2.

Coherent vortical structures found in a shear‐driven flat‐plate turbulent boundary layer. From Head and Bandyopadhyay , see also Robinson .

Figure 3. Figure 3.

A visualization of a plane mixing layer between helium (upper) at a speed of 10.1 m/s and nitrogen (lower) at 3.8 m/s. From .

Figure 4. Figure 4.

Contours of streamwise velocity in pipe flow through a 50% constriction (D, diameter of the tube) at Re = 2000.

Figure 5. Figure 5.

Velocity vector field and contours of speed at cross sections within the trachea (A and D), the left main bronchus (B and E), and the right main bronchus (C and F) for computational fluid dynamics simulation of airflow with (case 1: A‐C) and without (case 2: D‐F) including the upper airways. Reproduced with permission from Lin et al. .

Figure 6. Figure 6.

Outlet velocity vectors (pink) and pressure contours for three different downstream boundary conditions: (A) image‐based boundary condition; (B) uniform velocity; (C) uniform pressure. The pressure at the trachea pt is used as a reference. (D) Flow partitions in the five lobes. LUL, left upper lobe; LLL, left lower lobe; RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe. Reproduced with permission from Yin et al. .

Figure 7. Figure 7.

Large eddy simulation–generated airflow structures in two airway models based on multidetector row computed tomography. Laryngeal jet structures are indicated by isosurfaces of mean speed and contours in a vertical plane cutting through the vocal cord and the trachea. Reproduced with permission from Choi et al. .

Figure 8. Figure 8.

Velocity distributions in the bifurcation plane and two cross sections at Re = 740, L/a = 15, α = 7 (point B in Figure ) at: (A) end inspiration and (B) end expiration. A sinusoidal waveform is imposed at the inlet of the parent branch with 0 ≤ t/T ≤ 0.5 (0.5 ≤ t/T ≤ 1) for inspiratory (expiratory) phase. Blue, negative axial velocity to the left; red, positive axial velocity to the right. The vector length in the two cross sections is magnified four times for clarity. Reproduced with permission from Choi et al. .

Figure 9. Figure 9.

Velocity vectors at end inspiration (t/T = 0.47) and end expiration (t/T = 0.97) in the bifurcation plane at the bifurcation between generations 2 and 3. Red (blue), positive (negative) axial velocity in the parent branch to the right (left). (A and B) NORM (a normal breathing case); (C and D) HFNR (a high‐frequency normal Re case); and (E and F) HFOV (a high‐frequency oscillatory ventilation case). Re at the parent branch is 64 for (A‐D) and 182 for (E and F). Reproduced with permission from Choi et al. .

Figure 10. Figure 10.

Instantaneous particle transport profiles and contours of velocity magnitude for: (A) 2.5‐μm particles, (B) 20‐μm particles.

Figure 11. Figure 11.

Time histories of the maximum shear stresses in a rigid airway, a flexible airway, and a flexible airway wall with parenchymal tethering. Reproduced with permission from Xia et al. .

Figure 12. Figure 12.

Wall shear stress distribution at t = 0.25T, Re = 183 in (A) rigid airway; (B) flexible airway; and (C) flexible airway wall with parenchymal tethering. Wall shear stress is shown in units of Pa, with red indicating highest stress and dark blue lowest stress. Reproduced with permission from Xia et al. .

Figure 13. Figure 13.

An illustration of registration‐derived moving airway geometries at four different time points in a breathing cycle: (A), t = 0; (B), t = T/6; (C), t = T/3; and (D), t = T/2, with T as the period. This moving model is derived from a pair of volumetric multidetector row computed tomographic data sets with a lung volume change of 1.5 liters and the geometries at (A) and (D) correspond to the lower and higher lung volumes, respectively.

Figure 14. Figure 14.

Three‐ and one‐dimensional coupled airway tree and five lobes at (A) the minimum volume (55% vital capacity [VC]) and (B) the maximum lung volume (85%VC). (C) The distribution of deformation as a function of normalized lung height from the apex (100%) of the lung to the base (0%) calculated from the Jacobian‐estimated volume change. ΔV and ΔL denote volume and length changes. The subscript “max” corresponds to the maximum lung volume.



Figure 1.

Flow regimes of the conducting airway categorized on the basis of a dimensionless frequency α2 (where α is the Womersley number) and a dimensionless stroke length L/a. The (I) unsteady, (II) viscous, and (IIIa, IIIb) convective flow regimes are classified according to Jan et al. .



Figure 2.

Coherent vortical structures found in a shear‐driven flat‐plate turbulent boundary layer. From Head and Bandyopadhyay , see also Robinson .



Figure 3.

A visualization of a plane mixing layer between helium (upper) at a speed of 10.1 m/s and nitrogen (lower) at 3.8 m/s. From .



Figure 4.

Contours of streamwise velocity in pipe flow through a 50% constriction (D, diameter of the tube) at Re = 2000.



Figure 5.

Velocity vector field and contours of speed at cross sections within the trachea (A and D), the left main bronchus (B and E), and the right main bronchus (C and F) for computational fluid dynamics simulation of airflow with (case 1: A‐C) and without (case 2: D‐F) including the upper airways. Reproduced with permission from Lin et al. .



Figure 6.

Outlet velocity vectors (pink) and pressure contours for three different downstream boundary conditions: (A) image‐based boundary condition; (B) uniform velocity; (C) uniform pressure. The pressure at the trachea pt is used as a reference. (D) Flow partitions in the five lobes. LUL, left upper lobe; LLL, left lower lobe; RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe. Reproduced with permission from Yin et al. .



Figure 7.

Large eddy simulation–generated airflow structures in two airway models based on multidetector row computed tomography. Laryngeal jet structures are indicated by isosurfaces of mean speed and contours in a vertical plane cutting through the vocal cord and the trachea. Reproduced with permission from Choi et al. .



Figure 8.

Velocity distributions in the bifurcation plane and two cross sections at Re = 740, L/a = 15, α = 7 (point B in Figure ) at: (A) end inspiration and (B) end expiration. A sinusoidal waveform is imposed at the inlet of the parent branch with 0 ≤ t/T ≤ 0.5 (0.5 ≤ t/T ≤ 1) for inspiratory (expiratory) phase. Blue, negative axial velocity to the left; red, positive axial velocity to the right. The vector length in the two cross sections is magnified four times for clarity. Reproduced with permission from Choi et al. .



Figure 9.

Velocity vectors at end inspiration (t/T = 0.47) and end expiration (t/T = 0.97) in the bifurcation plane at the bifurcation between generations 2 and 3. Red (blue), positive (negative) axial velocity in the parent branch to the right (left). (A and B) NORM (a normal breathing case); (C and D) HFNR (a high‐frequency normal Re case); and (E and F) HFOV (a high‐frequency oscillatory ventilation case). Re at the parent branch is 64 for (A‐D) and 182 for (E and F). Reproduced with permission from Choi et al. .



Figure 10.

Instantaneous particle transport profiles and contours of velocity magnitude for: (A) 2.5‐μm particles, (B) 20‐μm particles.



Figure 11.

Time histories of the maximum shear stresses in a rigid airway, a flexible airway, and a flexible airway wall with parenchymal tethering. Reproduced with permission from Xia et al. .



Figure 12.

Wall shear stress distribution at t = 0.25T, Re = 183 in (A) rigid airway; (B) flexible airway; and (C) flexible airway wall with parenchymal tethering. Wall shear stress is shown in units of Pa, with red indicating highest stress and dark blue lowest stress. Reproduced with permission from Xia et al. .



Figure 13.

An illustration of registration‐derived moving airway geometries at four different time points in a breathing cycle: (A), t = 0; (B), t = T/6; (C), t = T/3; and (D), t = T/2, with T as the period. This moving model is derived from a pair of volumetric multidetector row computed tomographic data sets with a lung volume change of 1.5 liters and the geometries at (A) and (D) correspond to the lower and higher lung volumes, respectively.



Figure 14.

Three‐ and one‐dimensional coupled airway tree and five lobes at (A) the minimum volume (55% vital capacity [VC]) and (B) the maximum lung volume (85%VC). (C) The distribution of deformation as a function of normalized lung height from the apex (100%) of the lung to the base (0%) calculated from the Jacobian‐estimated volume change. ΔV and ΔL denote volume and length changes. The subscript “max” corresponds to the maximum lung volume.

References
 1. Adler K, Brücker C. Dynamics flow in a realistic model of the upper human lung airways. Exp Fluids 43 (2‐3): 411‐423, 2007.
 2. Ahmed SA, Giddens, DP. Velocity measurements in steady flow through axisymmetric stenoses at moderate Reynolds numbers. J Biomech 16: 505‐516, 1983.
 3. Allen GM, Shortall BP, Gemci T, Corcoran TE, Chigier NA. Computational simulations of airflow in an in vitro model of the pediatric upper airways. J Biomech Eng ‐ Trans ASME 126 (5): 604‐613, 2004.
 4. Bake B, Wood L, Murphy B, Macklem PT, Milic‐Emili, J. Effect of inspiratory flow rate on regional distribution of inspired gas. J Appl Physiol 37 (1): 8‐17, 1974.
 5. Balásházy I, Hofmann W, Heistracher T. Local particle deposition patterns may play a key role in the development of lung cancer. J Appl Physiol 94: 1719‐1725, 2003.
 6. Ball CG, Uddin M, Pollard A. High resolution turbulence modelling of airflow in an idealised human extra‐thoracic airway. Comput Fluids 37: 943‐964, 2008.
 7. Bennett WD. Targeting respiratory drug delivery with aerosol boluses. J Aerosol Med 4: 69‐78, 1991.
 8. Brouns M, Jayaraju ST, Lacor C, De Mey J, Noppen M, Vincken W. Tracheal stenosis: A flow dynamics study. J Appl Physiol 102 (3): 1178‐1184, 2007.
 9. Brouns M, Verbanck S, Lacor C. Influence of glottic aperture on the tracheal flow [2006]. J Biomech 40: 165‐172, 2007.
 10. Brown GL, Roshko, A. On density effects and large structure in turbulent mixing layers. J Fluid Mech 64: 775‐816, 1974.
 11. Bull JL, Grotberg JB. Surfactant spreading on thin viscous films: Film thickness evolution and periodic wall stretch. Exp Fluids 34: 1‐15, 2003.
 12. Button B, Boucher RC. Role of mechanical stress in regulating airway surface hydration and mucus clearance rates. Respir Physiol Neurobiol 163: 189‐201, 2008.
 13. Button B, Picher M, Boucher RC. Differential effects of cyclic and constant stress on ATP release and mucociliary transport by human airway epithelia. J Physiol 580 (2): 577‐592, 2007.
 14. Caro C. Swirling steady inspiratory flow in models of human bronchial airways (abstract of presentation at BMES annual meeting, RTP 2001). Ann Biomed Eng 29 (S1): S138, 2001.
 15. Chang HK. Mechanisms of gas transport during ventilation by high‐frequency oscillation. J Appl Physiol 56: 553‐563, 1984.
 16. Choi J, Tawhai MH, Hoffman EA, Lin C‐L. On intra‐ and intersubject variabilities of airflow in the human lungs. Phys Fluids 21: 101901, 2009.
 17. Choi J, Xia G, Tawhai MH, Hoffman EA, Lin C‐L. Numerical study of high frequency oscillatory air flow and convective mixing in a CT‐based human airway model. Ann Biomed Eng 2010. doi:10.1007/s10439‐010‐0110‐7.
 18. Cohen BS, Briant JK. Flow distribution in human and canine tracheobronchial airway casts. Health Phys 57 (suppl 1): 21‐27, 1989.
 19. Comer JK, Kleinstreuer C, Hyun S, Kim CS. Aerosol transport and deposition in sequentially bifurcating airways. J Biomech Eng 122: 152‐158, 2000.
 20. Comer JK, Kleinstreuer C, Zhang Z. Flow structures and particle deposition patterns in double‐bifurcation airway models. Part 1. Airflow fields. J Fluid Mech 435: 25‐54, 2001.
 21. Comer JK, Kleinstreuer C, Zhang Z. Flow structures and particle deposition patterns in double‐bifurcation airway models. Part 2. Aerosol transport and deposition. J Fluid Mech 435: 55‐80, 2001.
 22. Dailey HL, Yalcin HC, Ghadiali SN. Fluid‐structure modeling of flow‐induced alveolar epithelial cell deformation. Comput Struct 85: 1066‐1071, 2007.
 23. De Backer JW, Vos WG, Devolder A, Verhulst SL, Germonpré P, Wuyts FL, Parizel PM, De Backer W. Computational fluid dynamics can detect changes in airway resistance in asthmatics after acute bronchodilation. J Biomech 41 (1): 106‐113, 2008.
 24. De Backer JW, Vos WG, Gorlé CD, Germonpré P, Partoens B, Wuyts FL, Parizel PM, De Backer W. Flow analyses in the lower airways: Patient‐specific model and boundary conditions. Med Eng Phys 30 (7): 872‐879, 2008.
 25. De Backer LA, Vos WG, Verhulst SL, De Backer JW, Devolder A, Germonpre P, De Backer WA. Open, randomized, two‐way crossover, pilot study to assess the effect of salbutamol in comparison with ipratropium bromide on central and peripheral airway dimensions in COPD patients, comparing new methods of evaluation (CFD) with classical lung function tests. Am J Respir Crit Care Med 170 (ATS abstr issue): A4576, 2009.
 26. Doorly DJ, Taylor DJ, Schroter RC. Mechanics of airflow in the human nasal airways. Respir Physiol Neurobiol 163 (1‐3): 100‐110, 2008.
 27. Espinosa FF, Kamm RD. Thin layer flows due to surface tension gradients over a membrane undergoing non‐uniform, periodic strain. Ann Biomed Eng 25: 913‐925, 1997.
 28. Fain SB, Peterson ET, Evans M, Granroth JC, Newell J, Hoffman E, Kuhlman JE, Jarjour N, Wenzel S, Castro M. The SARP network investigators. Airway abnormalities are localized to specific regions in severe vs. non‐severe asthma. Am J Respir Crit Care Med 177 (ATS abstr issue): A29, 2008.
 29. Finlay WH. The Mechanics of Inhaled Pharmaceutical Aerosols (An Introduction). London: Academic Press, 2001.
 30. Fredberg JJ, Kamm RD. Stress transmission in the lung: Pathways from organ to molecule. Annu Rev Physiol 68: 507‐541, 2006.
 31. Gauderman WJ, Avol E, Gilliland F, Vora H, Thomas D, Berhane K, McConnell R, Kuenzli N, Lurmann F, Rappaport E, Margolis H, Bates D, Peters J. The effect of air pollution on lung development from 10 to 18 years of age. New Engl J Med 351 (11): 1057‐1067, 2004.
 32. Gemci T, Ponyavin V, Chen Y, Chen H, Collins, R. Computational model of airflow in upper 17 generations of human respiratory tract. J Biomech 41: 2047‐2054, 2008.
 33. Graham SM, McLennan G, Funk GF, Hoffman HT, McCulloch TM, Cook‐Granroth J, Hoffman EA. Preoperative assessment of obstruction with computed tomography image analysis. Am J Otolaryngol 21 (4): 263‐270, 2000.
 34. Green AS. Modelling of peak‐flow wall shear stress in major airways of the lung. J Biomech 37 (5): 661‐667, 2004.
 35. Grgic B, Finlay WH, Heenan AF. Regional aerosol deposition and flow measurements in an idealized mouth and throat. J Aerosol Sci 35: 21‐32, 2004.
 36. Grgic B, Heenan AF, Burnell PKP, Finlay WH. In vitro intersubject and intrasubject deposition measurements in realistic mouth‐throat geometries. J Aerosol Sci 35: 1025‐1040, 2004.
 37. Halpern D, Grotberg JB. Nonlinear saturation of the Rayleigh instability in a liquid‐lined tube due to oscillatory flow. J Fluid Mech 492: 251‐270, 2003.
 38. Head MR, Bandyopadhyay P. New aspects of turbulent boundary layer structure. J Fluid Mech 107: 297‐338, 1981.
 39. Heenan AF, Finlay WH, Grgic B, Pollard A, Burnell PKP. An investigation of the relationship between the flow field and regional deposition in realistic extra‐thoracic airways. J Aerosol Sci 35: 1013‐1023, 2004.
 40. Heenan AF, Matida E, Pollard A, Finlay WH. Experimental measurements and computational modeling of the flow field in an idealized human oropharynx. Exp Fluids 35: 70‐84, 2003.
 41. Heraty KB, Laffey JG, Quinlan NJ. Fluid dynamics of gas exchange in high‐frequency oscillatory ventilation: In vitro investigations in idealized and anatomically realistic airway bifurcation models. Ann Biomed Eng 36 (11): 1856‐1869, 2008.
 42. Holmes P, Lumley JL, Berkooz G. Turbulence, Coherent Structures, Dynamical Systems and Symmetry. Cambridge University Press, Cambridge, U.K. 1996.
 43. Horsfield K, Dart G, Olson DE, Filley GF, Cumming G. Models of the human bronchial tree. J Appl Physiol 31: 207‐217, 1971.
 44. Jan DL, Shapiro AH, Kamm RD. Some features of oscillatory flow in a model bifurcation. J Appl Physiol 67: 147‐159, 1989.
 45. Jayaraju ST, Brouns M, Lacor C, Belkassem B, Verbanck S. Large eddy and detached eddy simulations of fluid flow and particle deposition in a human mouth‐throat. J Aerosol Sci 39: 862‐875, 2008.
 46. Kamm RD. Airway wall mechanics. Ann Rev Biomed Eng 1: 47‐72, 1999.
 47. Kamm RD, Bullister ET, Keramidas C. The effect of a turbulent jet on gas transport during oscillatory flow. J Biomech Eng 108: 266‐272, 1986.
 48. Katz IM, Davis BM, Martonen TB. A numerical study of particle motion within the human larynx and trachea. J Aerosol Sci 30: 173‐183, 1999.
 49. Katz IM, Martonen TB. Flow patterns in three‐dimensional laryngeal models. J Aerosol Med 9 (4): 501‐511, 1996.
 50. Kim WD, Ling SH, Coxson HO, English JC, Yee J, Lvy RD, Pare PD, Hogg JC. The association between small airway obstruction and emphysema phenotypes in COPD. Chest 131: 1372‐1378, 2007.
 51. Kleinstreuer C, Zhang Z. Airflow and particle transport in the human respiratory system. Ann Rev Fluid Mech 42: 301‐334, 2010.
 52. Krishnan JA, Brower RG. High frequency ventilation for acute lung injury and ARDS. Chest 118: 795‐807, 2000.
 53. Kumar H, Tawhai MH, Hoffman EA, Lin C‐L. The effects of geometry on airflow in the acinar region of the human lung. J Biomech 42 (11): 1635‐1642, 2009.
 54. Lambert AR, O'Shaughnessy PT, Tawhai MH, Hoffman EA, Lin C‐L. Regional deposition of particles in an image‐based airway model: Large‐eddy simulation and left‐right lung ventilation asymmetry. Aerosol Sci Tech 45 (1): 11‐25, 2011.
 55. Lieber BB, Zhao Y. Oscillatory flow in a symmetric bifurcation airway model. Ann Biomed Eng 26 (5): 821‐830, 1998.
 56. Lin C‐L, Tawhai MH, McLennan G, Hoffman EA. Characteristics of the turbulent laryngeal jet and its effect on airflow in the human intra‐thoracic airways. Respir Physiol Neurobiol 157 (2‐3): 295‐309, 2007.
 57. Lin C‐L, Tawhai MH, McLennan G, Hoffman EA. Multiscale simulation of gas flow in subject‐specific models of the human lung. IEEE Eng Med Biol 28 (3): 25‐33, 2009.
 58. Liu Y, So RMC, Zhang CH. Modeling the bifurcating flow in an asymmetric human lung airway. J Biomech 36: 951‐959, 2003.
 59. Longest PW, Vinchurkar S. Validating CFD predictions of respiratory aerosol deposition: Effects of upstream transition and turbulence. J Biomech 40: 305‐316, 2007.
 60. Luo HY, Liu Y. Particle deposition in a CT‐scanned human lung airway. J Biomech 42: 1869‐1876, 2009.
 61. Ma B, Lutchen KR. An anatomically based hybrid computational model of the human lung and its application to low frequency oscillatory mechanics. Ann Biomed Eng 34 (11): 1691‐1704, 2006.
 62. Ma B, Ruwet V, Corieri P, Theunissen R, Riethmuller M, Darquenne C. CFD simulation and experimental validation of fluid flow and particle transport in a model of alveolated airways. J Aerosol Sci 40 (5): 403‐414, 2009
 63. Martonen TB, Zhang Z, Yang Y. Airway surface irregularities promote particle diffusion in the human lung. Radiat Prot Dosimetry 59: 5‐18, 2005.
 64. Möller W, Meyer G, Scheuch G, Kreyling WG, Bennett WD. Left‐to‐right asymmetry of aerosol deposition after shallow bolus inhalation depends on lung ventilation. J Aerosol Med Pulm Drug Deliv 22: 1‐7, 2009.
 65. Nagels MA, Cater JE. Large eddy simulation of high frequency oscillating flow in an asymmetric branching airway model. Med Eng Phys 31 (9): 1148‐1153, 2009.
 66. Nowak N, Kakade PP, Annapragada AV. Computational fluid dynamics simulation of airflow and aerosol deposition in human lungs. Ann Biomed Eng 31 (4): 374‐390, 2003.
 67. Nucci G, Suki B, Lutchen K. Modeling airflow‐related shear stress during heterogeneous constriction and mechanical ventilation. J Appl Physiol 95 (1): 348‐356, 2003.
 68. Oscar AP, Bryant MB, Panza JA. Role of endothelial nitric oxide in shear stress‐induced vasodilation of human microvasculature: Diminished activity in hypertensive and hypercholesterolemic patients. Circulation 103: 1752‐1758, 2001.
 69. Paszkowiak JJ, Dardik A. Arterial wall shear stress: Observations from the bench to the bedside. Vasc Endovasc Surg 37: 47‐57, 2003.
 70. Pedley TJ. Pulmonary fluid dynamics. Ann Rev Fluid Mech 9: 229‐274, 1977.
 71. Pedley TJ, Schroter RC, Sudlow MF. The prediction of pressure drop and variation of resistance within the human bronchial airways. Respir Physiol 9: 387‐405, 1970.
 72. Pedley TJ, Schroter RC, Sudlow MF. Energy losses and pressure drop in models of human airways. Respir Physiol 9: 371‐386, 1970.
 73. Pedley TJ, Schroter RC, Sudlow MF. Flow and pressure drop in systems of repeatedly branching tubes. J Fluid Mech 46 (2): 365‐383, 1971.
 74. Perktold K, Rappitsch G. Computer simulation of local blood flow and vessel mechanics in a compliant carotid artery bifurcation model. J Biomech 28: 845‐856, 1995.
 75. Picher M, Burch LH, Boucher RC. Metabolism of P2 receptor agonists in human airways: Implications for mucociliary clearance and cystic fibrosis. J Biol Chem 279(19): 20234‐20241, 2004.
 76. Pope SB. Turbulent Flows. Cambridge University Press, Cambridge, U.K. 2003.
 77. Rakesh V, Datta AK, Ducharme NG, Pease AP. Simulation of turbulent airflow using a CT based upper airway model of a racehorse. J Biomech Eng 130 (3): 031011, 2008.
 78. Robinson SK. Coherent motions in the turbulent boundary layer. Ann Rev Fluid Mech 23: 601‐639, 1991.
 79. Schroter RC, Sudlow MF. Flow patterns in models of the human bronchial airways. Respir Physiol 7: 341‐355, 1969.
 80. Sera T, Satoh S, Horinouchi H, Kobayashi K, Tanishita K. Respiratory flow in a realistic tracheostenosis model. J Biomech Eng 125 (4): 461‐471.
 81. Sherwin SJ, Blackburn HM. Three‐dimensional instabilities and transition of steady and pulsatile axisymmetric stenotic flows. J Fluid Mech 533: 297‐327, 2005.
 82. Sidhaye VK, Schweitzer KS, Caterina MJ, Shimoda L, King LS. Shear stress regulates aquaporin‐5 and airway epithelial barrier function. Proc Natl Acad Sci U S A 105: 3345‐3350, 2008.
 83. Stapleton K, Guentsch E, Hoskinson MK, Finlay WH. On the suitability of k‐ɛ turbulence modeling for aerosol deposition in the mouth and throat. J Aerosol Sci 31 (6): 739‐749, 2000.
 84. Subramaniam RP, Asgharian B, Freijer JI, Miller FJ, Anjilvel S. Analysis of lobar differences in particle deposition in the human lung. Inhal Technol 15: 1‐21, 2003.
 85. Sznitman J, Heimsch F, Heimsch T, Rusch D, Rösgen T. Three‐dimensional convective alveolar flow induced by rhythmic breathing motion of the pulmonary acinus. J Biomech Eng 129 (5): 658‐665, 2007.
 86. Tanaka G, Ogata T, Oka K, Tanishita K. Spatial and temporal variation of secondary flow during oscillatory flow in model human central airways. J Biomech Eng 121: 565‐573, 1999.
 87. Tarran R, Button B, Picher M, Paradiso AM, Ribeiro CM, Lazarowski ER, Zhang L, Collins PL, Pickles RJ, Fredberg JJ, Boucher RC. Normal and cystic fibrosis airway surface liquid homeostasis: The effects of phasic shear stress and viral infections. J Biol Chem 280 (42): 35751‐35759, 2005.
 88. Tawhai M, Pullan AJ, Hunter PJ. Generation of an anatomically based three‐dimensional model of the conducting airways. Ann Biomed Eng 28: 793‐802, 2000.
 89. Tawhai MH, Hunter PJ, Tschirren J, Reinhardt JM, McLennan G, Hoffman EA. CT‐based geometry analysis and finite element models of the human and ovine bronchial tree. J Appl Physiol 97 (6): 2310‐2321, 2004.
 90. Taylor CA, Hughes TJR, Zarins CK. Finite element blood flow modeling in arteries. Comput Method Appl Mech Eng 158: 155‐196, 1998.
 91. Tippe A, Tsuda A. Recirculating flow in an expanding alveolar model: Experimental evidence of flow‐induced mixing of aerosols in the pulmonary acinus. J Aerosol Sci 31 (8): 979‐986, 2000.
 92. Tschumperlin DJ, Drazen JM. Chronic effects of mechanical force on airways. Annu Rev Physiol 68: 563‐583, 2006.
 93. Tschumperlin DJ, Shively JD, Kikuchi T, Drazen JM. Mechanical stress triggers selective release of fibrotic mediators from bronchial epithelium. Am J Respir Cell Mol Biol 28: 142‐149, 2003.
 94. Tschumperlin DJ, Shively JD, Swartz MA, Silverman ES, Haley KJ, Raab G, Drazen JM. Bronchial epithelial compression regulates MAP kinase signaling and HB‐EGF‐like growth factor expression. Am J Physiol Lung Cell Mol Physicol 282: L904‐L911, 2002.
 95. Tsuda A, Henry FS, Butler JP. Chaotic mixing of alveolated duct flow in rhythmically expanding pulmonary acinus. J Appl Physiol 79: 1055‐1063, 1995.
 96. Uchida S, Aoki H. Unsteady flows in a semi‐infinite contracting or expanding pipe. J Fluid Mech 82 (2): 371‐387, 1977.
 97. Urquiza SA, Blanco PJ, Venere MJ, Feijoo RA. Multidimensional modelling for the carotid artery blood flow. Comput Method Appl Mech Eng 195: 4002‐4017, 2006.
 98. van Ertbruggen C, Hirsch C, Paiva M. Anatomically based three‐dimensional model of airways to simulate flow and particle transport using computational fluid dynamics. J Appl Physiol 98: 970‐980, 2005.
 99. Varghese SS, Frankel SH, Fischer PF. Direct numerical simulation of stenotic flows, Part 1: Steady flow. J Fluid Mech 582: 253‐280, 2007.
 100. Vetel J, Garon A, Pelletier D, Farnias M‐I. Asymmetry and transition to turbulence in a smooth axisymmetric constriction. J Fluid Mech 607: 351‐386, 2008.
 101. Wagner EM, Liu MC, Weinman GG, Permutt S, Bleecker ER. Peripheral lung resistance in normal and asthmatic subjects. Am Rev Respir Dis 141: 584‐588, 1990.
 102. Weibel ER. Morphometry of the Human Lung. Berlin: Springer‐Verlag, 1963.
 103. West JB, Hugh‐Jones P. Patterns of gas flow in the upper bronchial tree. J Appl Physiol 14: 753‐759, 1959.
 104. West JB. Observations on gas flow in the human bronchial tree. In: Davies CN, editor. Inhaled Particles and Vapours. New York: Pergamon Press, 3‐7, 1961.
 105. West JB. Respiratory Physiology: The Essentials. Baltimore, MD: Lippincott Williams & Wilkins, 2005.
 106. Wilcox DC. Turbulence Modeling for CFD. DCW Industries, Inc., La Canada, California 1994.
 107. Womersley JR. Method for the calculation of velocity, rate of flow and viscous drag in arteries when the pressure gradient is known. J Physiol 127: 553‐563, 1955.
 108. Xia G, Lin C‐L. An unstructured finite volume approach for structural dynamics in response to fluid motions. Comput Struct 86: 684‐701, 2008.
 109. Xia G, Tawhai MH, Hoffman EA, Lin CL. Airway wall stiffening increases peak wall shear stress: A fluid‐structure interaction study in rigid and compliant airways. Ann Biomed Eng 2010. doi:10.1007/s10439‐010‐9956‐y.
 110. Yanai M, Sekizawa K, Ohrui T, Sasaki H, Takishima T. Site of airway obstruction in pulmonary disease: Direct measurement of intrabronchial pressure. J Appl Physiol 72: 1016‐1023, 1992.
 111. Yin Y, Choi J, Hoffman EA, Tawhai MH, C‐L L. Simulation of pulmonary air flow with a subject‐specific boundary condition. J Biomech 2010. doi:10.1016/j.jbiomech.2010.03.048.
 112. Yin Y, Hoffman EA, Lin C‐L. Mass preserving nonrigid registration of CT lung images using cubic B‐spline. Med Phys 36 (9): 4213‐4222, 2009.
 113. Yu C‐C, Hsiao H‐D, Lee L‐C, Yao C‐M, Chen N‐H, Wang C‐J, Chen Y‐R. Computational fluid dynamic study on obstructive sleep apnea syndrome treated with maxillomandibular advancement. J Craniofac Surg 20 (2): 426‐430, 2009.
 114. Zhang Y, Finlay W. Measurement of the effect of cartilaginous rings on particle deposition in a proximal lung bifurcation model. Aerosol Sci Technol 39 (5): 394‐399, 2005.
 115. Zhang Z, Kleinstreuer C. Transient airflow structures and particle transport in a sequentially branching lung airway model. Phys Fluids 14 (2): 862‐880, 2002.
 116. Zhang Z, Kleinstreuer C. Airflow structures and nano‐particle deposition in a human upper airway model. J Comput Phys 198: 178‐210, 2004.
 117. Zhang Z, Kleinstreuer C, Kim CS. Comparison of analytical and CFD models with regard to micron particle deposition in a human 16‐generation tracheobronchial airway model. Aerosol Sci Technol 40: 16‐28, 2009.
 118. Zhang Z, Kleinstreuer C, Kim CS, Hickey AJ. Aerosol transport and deposition in a triple bifurcation bronchial airway model with local tumors. Inhal Toxicol 14: 1111‐1133, 2002.

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How to Cite

Merryn H. Tawhai, Ching‐Long Lin. Airway Gas Flow. Compr Physiol 2011, 1: 1135-1157. doi: 10.1002/cphy.c100020