مدلسازي جذب ذرات در لب هاي پنج گانه ريه با استفاده از روش Monte Carlo

چكيده انگليسي :

Monte Carlo modeling of aerosol deposition in human lung s five lobes Ramin Dastanpour r dastanpour@gmail com September 15 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Prof Mohammad Said Saidi mssaidi@sharif edu Dr Ahmad Reza Pishevar apishe@cc iut ac ir AbstractWe are always in direct contact with ambient aerosols ranging from toxic to drug aerosols These particlesmainly enter the human body via their respiratory system Human s respiratory system could be divided intothree regions i oro nasal cavities ii tracheobronchial tree and iii acinar pulmonary region Contrary to thetracheobronchial tree airways acinar airways are flexible and they expand during inspiration Additionally O2 CO2 exchange occurs in this region Several mathematical models have been developed to simulate the geometry of human lung airways Weibel developed the simplest model of the lung airways network which is completely planar andsymmetrical Opposite to this simple unrealistic model Raabi and Horsfield provided partial and completelyasymmetric models respectively using data obtained from real lung resin castings These models representpre specified geometries for human lung such as diameter length number of airways branching and gravityangles Hofmann provided a set of statistical distributions for the above mentioned parameters of human lungstructure by using more resin casting samples Airflow and particle deposition in human lung have been analyzed by a number of researchers Eventhough some of them have simulated deposition in a sample bifurcation through a set of airways or in asymmetric lung but none of them have simulated a whole asymmetric unpredefined lung yet In this project particle deposition in the five lobes of human lung is simulated The simulation is based ona stochastic lung model derived from detailed morphometric measurements of Raabi and Hofmann Pathways are simulated using Monte Carlo methods consequently the whole lung structure changes bothstochastically and statistically in each simulation These stochastic lungs contain about 14 millions airwaysand 8 millions single paths Acinar region is assumed as a pack connected to the last tracheobronchial tree airways This packcontains 9 generation and has 0 187 cm3 volume In the previous works flow division in bifurcations is started from trachea and is continued downward Furthermore whole long airways have not been simulated in these earlier works As a result ducts outletboundary conditions could not be determined accurately in these simulations According to the physiology ofrespiratory system air suction during inspiration is caused by the volume change of the pulmonary airways In this study flow rates in airways are computed in an upward manner starting from the acinus packs wheresuction occurs following to trachea The flux distribution results are compared to the previous availableassumptions i e flow divisions according to the ratio of daughters cross sections Regional and total deposition fractions in the human respiratory system are computed by the stochasticlung deposition model during inhalation exhalation and breath hold periods These fractions are computed ina stochastic lung instead of a pre defined lung structure Three case of inhalation are considered in this study i oral breathing ii nasal breathing and iii trachea breathing Simultaneous effects of Brownian motion inertial impaction and gravitational sedimentation are simulated in particle deposition analysis in respiratoryairways using analytical equations The effects of particle size density and inhalation flow rate variation arealso analysed in this study Key wordsMonte Carlo modeling Whole lung Five lobes Acinar pack Flow division Depositionfraction

داستانپور، رامين

مدلسازي جذب ذرات در لب هاي پنج گانه ريه با استفاده از روش Monte Carlo

مدل كلي ريه , پنج لب , مجموعه حبابچه اي , تقسيم جريان