نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 کارشناسی ارشد مهندسی هوا فضا-آیرودینامیک، دانشکده‌ی علوم و فنون نوین، دانشگاه تهران، تهران، ایران

2 دانشیار، بخش مهندسی پزشکی، گروه مهندسی علوم زیستی، دانشکده‌ی علوم وفنون نوین، دانشگاه تهران، تهران، ایران

3 دانشجوی کارشناسی ارشد مهندسی پزشکی-بیومکانیک، دانشکده‌ی علوم و فنون نوین، دانشگاه تهران، تهران، ایران

چکیده

سطح وسیع ریه با حصارهای هوایی-خونی خود، در معرض ذرات معلق هوای ورودی قرار دارد. در این شرایط، در صورت آلوده بودن این ذرات، اثر متقابل ذرات-ریه روی هم می­تواند خطرات و صدمات قابل توجهی را برای سلامتی انسان به همراه داشته باشد. از طرفی، از این واکنش­ها برای دارورسانی به بدن انسان نیز استفاده می‌شود. در هر دو حالت، تخمین دقیق مقدار و محل نشست ذرات در مجاری تنفسی، به عنوان مبنای درک مکانوبیولوژیکی این بیماری­ها به شمار می‌رود. گردآوری تجربی داده‌ها از انتقال ذرات در ریه‌ی انسان فرایند بسیار دشواری می‌باشد. اما روش دینامیک سیالات-ذرات محاسباتی، امکان شبیه‌سازی داده­های انتقال ذرات در مدل­های واقعی را فراهم ساخته است. نشست ذرات آیروسول در ریه‌ی انسان، از طریق ترکیب برخورد در اثر اینرسی، رسوب در اثر گرانش و انتشار روی می­دهد. مکانیسم اصلی نشست ذرات در مجاری پایین دست، برای ذراتی با قطر آیرودینامیکی 5/0 تا 5 میکرومتر و در حالت انبساط ریه (در حالت دم)، رسوب ناشی از نیروی گرانش و انتقال هم‌رفتی ناشی از حرکت دیواره­ها می­باشد. در این پژوهش، جریان سیال-ذره در نسل 18-ام از مجاری تنفسی مدل­سازی شده و میزان نشست ذرات در مجاری تنفسی برای دو حالت گرانش ناچیز و نرمال، با فرض تغییر­ مکان ایزوتروپیک در دیواره‌ها و میزان دبی ورودی 1 mg/s، مورد بررسی قرار گرفته است. بررسی نتایج به دست آمده نشان می‌دهد که به دلیل توانایی نفوذ ذرات با قطر آیرودینامیکی کم‌تر از 5 میکرومتر به نواجی عمیق مجاری تنفسی، با ناچیز کردن اثر نیروی گرانش، میزان نشست ذرات در مجاری پایین­دست سیستم تنفسی تا حد بسیار زیادی کاهش می­یابد. ذرات با قطر 5 میکرومتر، تحت تاثیر برخورد اینرسی (که بیش‌تر در مجاری با قطر بزرگ و متوسط روی می­دهد) و هم‌چنین در اثر رسوب (که بیش‌تر در مجاری پایین‌دست عمل می­کند)، دچار نشست می­شوند. 

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Computational Simulation of Airflow with Aerosols in Distal Parts of a Human Respiratory System: Investigating the Effects of Gravity

نویسندگان [English]

  • Mohammad Ahmadi Alashti 1
  • Bahman Vahidi 2
  • Mahtab Ebad 3

1 M.Sc. in Aerospace Engineering-Aerodynamics, Faculty of New Sciences and Technologies (FNST), University of Tehran, Tehran, Iran

2 Associate Professor, Biomedical Engineering Department, Faculty of New Sciences and Technologies (FNST), University of Tehran, Tehran, Iran

3 M.Sc. Student of Biomedical Engineering-Biomechanics, Faculty of New Sciences and Technologies (FNST), University of Tehran, Tehran, Iran

چکیده [English]

The large surface area of the lung with its thin air-blood barrier is exposed to particles in the inhaled air. In this condition, if the inhaled pollutant aerosols are toxic, the particle-lung interaction may cause serious hazards and injuries on human’s health. On the otherhand, these interactions are also used for drug delivery to human’s body. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental for understanding mechanobiology of these deseases. Obtaining in vivo data of particle transportation in the human lung experimentally is often difficult. But, computational fluid-particle dynamics (CFPD) has provided the possibility to gain aerosol transportion data in realistic airway geometries. Aerosols deposition in the human lung mainly occurs due to combination of inertial impaction, gravitational sedimentation and diffusion. For particles with aerodynamic size of 0.5 to 5 micron and in inhalation state of lung, the main mechanisms of particle deposition in distal parts of human’s respiratory system are sedimentation, due to gravity and convective transfer due to wall movement. In this study, deposition of particles in distal part of human respiratory system, specifically 18th generation, has been modeled for two gravity conditions, normal and absent gravity, by assuming isotropic displacements on the walls and with the rate of 1 (mg/sec) for particle input. By analyzing the results, it was determined that the amount of particle deposition in distal airways reduces a great amount by omitting the effect of gravitational force because, particles smaller than 5 micron can penetrate into that airways. Particles with the diameter of 5 micron deposit under the effect of inertial impact, whereas this mechanism occurs mostly in airways with large and medium diameters and also, by sedimentation which occurs in the distal lung.

کلیدواژه‌ها [English]

  • CFPD
  • Particles Deposition in Acinar Region
  • Alveolated Duct with Moving Wall
  • Distal Parts of Respiratory System
  • Micro-Gravity
[1]   R. Ullrich, "Etiology of cancer: Physical factors," Cancer: principles and practice of oncology, vol. 1, pp. 597-618, 2001.
[2]   F. Laden, M. J. Stampfer, and A. M. Walker, "Lung cancer and mesothelioma among male automobile mechanics: a review," Reviews on environmental health, vol. 19, pp. 39-62, 2004.
[3]   M. Goodman, M. J. Teta, P. A. Hessel, D. H. Garabrant, V. A. Craven, C. G. Scrafford, et al., "Mesothelioma and lung cancer among motor vehicle mechanics: a meta-analysis," Annals of Occupational Hygiene, vol. 48, pp. 309-326, 2004.
[4]   P. J. Landrigan, P. J. Lioy, G. Thurston, G. Berkowitz, L. Chen, S. N. Chillrud, et al., "Health and environmental consequences of the world trade center disaster," Environmental health perspectives, vol. 112, p. 731, 2004.
[5]   R. Herbert, J. Moline, G. Skloot, K. Metzger, S. Baron, B. Luft, et al., "The World Trade Center disaster and the health of workers: five-year assessment of a unique medical screening program," Environmental health perspectives, vol. 114, p. 1853, 2006.
[6]   U. D. o. Health and H. Services, "Agency for Toxic Substances and Disease Registry," Toxicological Profile for Chromium, 1993.
[7]   A. f. T. Substances and D. Registry, "Toxicological profile for asbestos," ed: US Department of Health and Human Services, Public Health Service Atlanta, GA, 2001.
[8]   K. M. O’REILLY, A. M. Mclaughlin, W. S. Beckett, and P. J. Sime, "Asbestos-related lung disease," Chest, vol. 100, p. 2, 2007.
[9]   E. R. Weibel, Geometry and dimensions of airways of conductive and transitory zones: Springer, 1963.
[10]K. Horsfield, G. Dart, D. E. Olson, G. F. Filley, and G. Cumming, "Models of the human bronchial tree," Journal of applied physiology, vol. 31, pp. 207-217, 1971.
[11]R. B. Schlesinger and M. Lippmann, "Selective particle deposition and bronchogenic carcinoma," Environmental Research, vol. 15, pp. 424-431, 1978.
[12]I. Balásházy, W. Hofmann, and T. Heistracher, "Local particle deposition patterns may play a key role in the development of lung cancer," Journal of Applied Physiology, vol. 94, pp. 1719-1725, 2003.
[13]D. Elad, R. Liebenthal, B. Wenig, and S. Einav, "Analysis of air flow patterns in the human nose," Medical and Biological Engineering and Computing, vol. 31, pp. 585-592, 1993.
[14]K. Keyhani, P. Scherer, and M. Mozell, "Numerical simulation of airflow in the human nasal cavity," Journal of biomechanical engineering, vol. 117, pp. 429-441, 1995.
[15]W. Hofmann, R. Golser, and I. Balashazy, "Inspiratory deposition efficiency of ultrafine particles in a human airway bifurcation model," Aerosol Science & Technology, vol. 37, pp. 988-994, 2003.
[16]Z. Zhang, C. Kleinstreuer, J. Donohue, and C. Kim, "Comparison of micro-and nano-size particle depositions in a human upper airway model," Journal of aerosol science, vol. 36, pp. 211-233, 2005.
[17]P. W. Longest and J. Xi, "Computational investigation of particle inertia effects on submicron aerosol deposition in the respiratory tract," Journal of Aerosol Science, vol. 38, pp. 111-130, 2007.
[18]G. Oberdörster, E. Oberdörster, and J. Oberdörster, "Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles," Environmental health perspectives, pp. 823-839, 2005.
[19]S. Wang, K. Inthavong, J. Wen, J. Tu, and C. Xue, "Comparison of micron-and nanoparticle deposition patterns in a realistic human nasal cavity," Respiratory physiology & neurobiology, vol. 166, pp. 142-151, 2009.
[20]P. Zamankhan, G. Ahmadi, Z. Wang, P. K. Hopke, Y.-S. Cheng, W. C. Su, et al., "Airflow and deposition of nano-particles in a human nasal cavity," Aerosol science and technology, vol. 40, pp. 463-476, 2006.
[21]H. Kumar, M. H. Tawhai, E. A. Hoffman, and C.-L. Lin, "Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows," Physics of Fluids, vol. 23, p. 041902, 2011.
[22]N. Khajeh-Hosseini-Dalasm and P. W. Longest, "Deposition of particles in the alveolar airways: inhalation and breath-hold with pharmaceutical aerosols," Journal of aerosol science, vol. 79, pp. 15-30, 2015.
[23]K. Talaat and J. Xi, "Computational modeling of aerosol transport, dispersion, and deposition in rhythmically expanding and contracting terminal alveoli," Journal of Aerosol Science, vol. 112, pp. 19-33, 2017.
[24]Y. Fung, "A model of the lung structure and its validation," Journal of Applied Physiology, vol. 64, pp. 2132-2141, 1988.
[25]C. Richmond, "Sir Godfrey Hounsfield," ed: BMJ Publishing Group, 2004.
[26]W. A. Kalender, H. Fichte, W. Bautz, and M. Skalej, "Semiautomatic evaluation procedures for quantitative CT of the lung," Journal of computer assisted tomography, vol. 15, pp. 248-255, 1991.
[27]M. Cannie, J. Jani, F. De Keyzer, F. Van Kerkhove, J. Meersschaert, L. Lewi, et al., "Magnetic resonance imaging of the fetal lung: a pictorial essay," European radiology, vol. 18, pp. 1364-1374, 2008.
[28]A. Tsuda, N. Filipovic, D. Haberthur, R. Dickie, Y. Matsui, M. Stampanoni, et al., "Finite element 3D reconstruction of the pulmonary acinus imaged by synchrotron X-ray tomography," Journal of Applied Physiology, vol. 105, pp. 964-976, 2008.
[29]K. Khan, J. Arino, W. Hu, P. Raposo, J. Sears, F. Calderon, et al., "Spread of a novel influenza A (H1N1) virus via global airline transportation," New England journal of medicine, vol. 361, pp. 212-214, 2009.
[30]W. Yan, Y. Zhang, Y. Sun, and D. Li, "Experimental and CFD study of unsteady airborne pollutant transport within an aircraft cabin mock-up," Building and Environment, vol. 44, pp. 34-43, 2009.
[31]J. B. West and A. Luks, West's respiratory physiology: the essentials: Wolters Kluwer, 2016.
[32]L. Waite and J. M. Fine, "Applied biofluid mechanics," 2007.
[33]J. Mead, T. Takishima, and D. Leith, "Stress distribution in lungs: a model of pulmonary elasticity," Journal of Applied Physiology, vol. 28, pp. 596-608, 1970.
[34]C. Van Ertbruggen, P. Corieri, R. Theunissen, M. Riethmuller, and C. Darquenne, "Validation of CFD predictions of flow in a 3D alveolated bend with experimental data," Journal of biomechanics, vol. 41, pp. 399-405, 2008.
[35]J. Sznitman, "Respiratory flows in the pulmonary acinus and insights on the control of alveolar flows," ETH, 2008.
[36]H. Kumar, M. H. Tawhai, E. A. Hoffman, and C.-L. Lin, "The effects of geometry on airflow in the acinar region of the human lung," Journal of biomechanics, vol. 42, pp. 1635-1642, 2009.
[37]C. Darquenne, L. Harrington, and G. Prisk, "Alveolar duct expansion greatly enhances aerosol deposition: a three-dimensional computational fluid dynamics study," Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, vol. 367, pp. 2333-2346, 2009.
[38]B. Haefeli‐Bleuer and E. R. Weibel, "Morphometry of the human pulmonary acinus," The Anatomical Record, vol. 220, pp. 401-414, 1988.
[39]M. M. R. Williams and S. K. Loyalka, "Aerosol science: Theory and practice," 1991.
[40]J. D. Brain and P. A. Valberg, "Deposition of aerosol in the respiratory tract," American Review of Respiratory Disease, vol. 120, pp. 1325-1373, 1979.
[41]C. Darquenne, "Aerosol deposition in the human lung in reduced gravity," Journal of aerosol medicine and pulmonary drug delivery, vol. 27, pp. 170-177, 2014.
[42]J. Tu, K. Inthavong, and G. Ahmadi, Computational fluid and particle dynamics in the human respiratory system: Springer Science & Business Media, 2012.
[43]O. C. Zienkiewicz, R. L. Taylor, and J. Z. Zhu, "The Finite Element Method: Its Basis and Fundamentals: Its Basis and Fundamentals," Butterworth-Heinemann, vol. 132, pp. 1987-1993, 2005.
[44]O.-P. Jacquotte and G. Coussement, "Structured mesh adaption: space accuracy and interpolation methods," Computer Methods in Applied Mechanics and Engineering, vol. 101, pp. 397-432, 1992.
[45]P. G. Tucker and A. Mosquera, "Introduction to grid and mesh generation for CFD," 2001.
[46]Y. Kallinderis, A. Khawaja, and H. McMorris, "Hybrid prismatic/tetrahedral grid generation for viscous flows around complex geometries," AIAA journal, vol. 34, pp. 291-298, 1996.
[47]X. Gu, H. Schock, T. Shih, E. Hernandez, and D. Chu, "Grid-quality measures for structured and unstructured meshes," in 39th Aerospace Sciences Meeting and Exhibit, 2001, p. 652.
[48]T. L. Bergman, F. P. Incropera, D. P. DeWitt, and A. S. Lavine, Fundamentals of heat and mass transfer: John Wiley & Sons, 2011.
[49]C. Darquenne, M. Paiva, J. B. West, and G. K. Prisk, "Effect of microgravity and hypergravity on deposition of 0.5-to 3-μm-diameter aerosol in the human lung," Journal of Applied Physiology, vol. 83, pp. 2029-2036, 1997.
[50]C. G. Caro, T. Pedley, and R. Schroter, The mechanics of the circulation: Cambridge University Press, 2012.
[51]S. Haber, J. Butler, H. Brenner, I. Emanuel, and A. Tsuda, "Shear flow over a self-similar expanding pulmonary alveolus during rhythmical breathing," Journal of Fluid Mechanics, vol. 405, pp. 243-268, 2000.
[52]J. Sandeau, I. Katz, R. Fodil, B. Louis, G. Apiou-Sbirlea, G. Caillibotte, et al., "CFD simulation of particle deposition in a reconstructed human oral extrathoracic airway for air and helium–oxygen mixtures," Journal of aerosol science, vol. 41, pp. 281-294, 2010.
[53]E. R. Weibel, "Geometry and dimensions of airways of conductive and transitory zones," in Morphometry of the human lung, ed: Springer, 1963, pp. 110-135.
[54]A. Tsuda, F. S. Henry, and J. P. Butler, "Chaotic mixing of alveolated duct flow in rhythmically expanding pulmonary acinus," Journal of Applied Physiology, vol. 79, pp. 1055-1063, 1995.
[55]F. S. Henry, J. P. Butler, and A. Tsuda, "Kinematically irreversible acinar flow: a departure from classical dispersive aerosol transport theories," Journal of Applied Physiology, vol. 92, pp. 835-845, 2002.