Study of Airflow and Particle Transport in Acinar Airways of the Human Lung PDF Download
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Author: Haribalan Kumar
Publisher:
ISBN:
Category : Lungs
Languages : en
Pages : 158
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Book Description
In this work, airflow and particle transport are studied using mathematical and image-based models of pulmonary acinus. Numerical results predict that airflow in the presence of wall motion in a three-dimensional honey-comb like geometry is characterized by the presence of a recirculation region within the alveolar cavity and a weak entraining flow between alveolar duct and cavity. Alveolar flow in distal generations is characterized by higher alveolar flow rates, larger entrainment of ductal flow and absence of recirculatory flow inside alveoli. The study of transport constitutes assessment of mixing visualized by the tracking of massless particles and the study of transport and deposition of aerosols. The phenomenon of steady streaming is found to hold the key to the origin of kinematic mixing in the alveolus, the alveolar mouth and the alveolated duct. This mechanism provides the explanation for observed folding of material lines and increases in material surface area, and has no bearing on whether the geometry is expanding or if flow separates within the cavity or not. Streaming results in non-zero drift of particles between the beginning and end of a breathing cycle. Based on flow conditions and resultant convective mixing measures, we conclude that significant convective mixing in the duct and within an alveolus could originate only in the first few generations of the acinar tree as a result of non-zero inertia, flow asymmetry and large KC number. Evidence of streaming and related Lagrangian drift is also observed in image-based acinar models. Finally, particle deposition calculations are performed on the models of pulmonary acinus considered in this study.
Author: Haribalan Kumar
Publisher:
ISBN:
Category : Lungs
Languages : en
Pages : 158
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Book Description
In this work, airflow and particle transport are studied using mathematical and image-based models of pulmonary acinus. Numerical results predict that airflow in the presence of wall motion in a three-dimensional honey-comb like geometry is characterized by the presence of a recirculation region within the alveolar cavity and a weak entraining flow between alveolar duct and cavity. Alveolar flow in distal generations is characterized by higher alveolar flow rates, larger entrainment of ductal flow and absence of recirculatory flow inside alveoli. The study of transport constitutes assessment of mixing visualized by the tracking of massless particles and the study of transport and deposition of aerosols. The phenomenon of steady streaming is found to hold the key to the origin of kinematic mixing in the alveolus, the alveolar mouth and the alveolated duct. This mechanism provides the explanation for observed folding of material lines and increases in material surface area, and has no bearing on whether the geometry is expanding or if flow separates within the cavity or not. Streaming results in non-zero drift of particles between the beginning and end of a breathing cycle. Based on flow conditions and resultant convective mixing measures, we conclude that significant convective mixing in the duct and within an alveolus could originate only in the first few generations of the acinar tree as a result of non-zero inertia, flow asymmetry and large KC number. Evidence of streaming and related Lagrangian drift is also observed in image-based acinar models. Finally, particle deposition calculations are performed on the models of pulmonary acinus considered in this study.
Author: Jiyuan Tu
Publisher: Springer Science & Business Media
ISBN: 9400744870
Category : Technology & Engineering
Languages : en
Pages : 383
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Book Description
Traditional research methodologies in the human respiratory system have always been challenging due to their invasive nature. Recent advances in medical imaging and computational fluid dynamics (CFD) have accelerated this research. This book compiles and details recent advances in the modelling of the respiratory system for researchers, engineers, scientists, and health practitioners. It breaks down the complexities of this field and provides both students and scientists with an introduction and starting point to the physiology of the respiratory system, fluid dynamics and advanced CFD modeling tools. In addition to a brief introduction to the physics of the respiratory system and an overview of computational methods, the book contains best-practice guidelines for establishing high-quality computational models and simulations. Inspiration for new simulations can be gained through innovative case studies as well as hands-on practice using pre-made computational code. Last but not least, students and researchers are presented the latest biomedical research activities, and the computational visualizations will enhance their understanding of physiological functions of the respiratory system.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
People may inhale 100 millions of particles each day, including toxic particulate matter as well as drug aerosols. Some of those deposited in the respiratory system can be either harmful or therapeutic to humans depending upon the particle material, deposition site, and local concentration. These transport and deposition phenomena as well as the resulting biomedical processes are greatly determined by the airflow field, particle properties, breathing pattern, and geometric airway characteristics. Realistic models of tracheobronchial and nasal⁄oral- tracheobronchial airways were built. Airflow and particle transport and deposition in these airway models were investigated in detail by mainly using the validated, in-house FORTRAN code CFPD (computational fluid-particle dynamics), which is a cell-centered, finite volume multi-block code. Both laminar and transitional-turbulent-laminar flows were considered for different transient and steady inhalation flow rates and inlet velocity profiles. The resulting effects of transients, upstream conditions and geometric characteristics, i.e., spatial angle and/or cartilaginous rings, are fully discussed. A new code based on the lattice-Boltzmann method (LBM) has been developed and validated to investigate airflow patterns and pressure changes in representative alveolar structures of the human respiratory zone. The new idea of targeted drug aerosol delivery technology was numerically tested for a more realistic human airway configuration and thereby addressing the problem of inter-subject variability. Specifically, controlled air-particle streams were studied using the oral and asymmetric tracheobronchial airway models. The results were compared with data obtained for a symmetric Weibel Type A tracheobronchial airway model.
Author: Chiu-sen Wang
Publisher: Elsevier
ISBN: 0080455018
Category : Technology & Engineering
Languages : en
Pages : 214
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Book Description
Inhaled Particles integrates all that is known about inhaled particles in a unified treatment. It aims to provide a scientific framework essential to a reasonable understanding of inhaled particles. The emphasis is placed on demonstrating the key roles of lung morphology on airflow and particle transport as well as identifying physical and biological factors that influence deposition. Special attention is paid to maintaining consistency of treatment and a balance between theoretical modeling and experimental measurements. The book covers all important aspects of inhaled particles including inhalability, aerosol dispersion, particle deposition, and clearance. It reviews concisely the basic background of lung morphology, respiratory physiology, aerodynamics, and aerosol science pertinent to the subject. Essential aspects of health effects and applications are also included. An easy-to-read, self contained introduction to the field An excellent source of updated research information Useful for students and professionals in aerosol science, environmental health science, occupational hygiene, health physics and biomedical engineering
Author: Zheng Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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Book Description
Keywords: Micro-Particle, Airflow, computational fluid dynamics, Lung Airway.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this work, we investigate particle deposition and air flow in thehuman lung. In particular we are interested in how the motion ofparticulate matter and air is affected by the presence of lungdisease. Patients with compromised lung function are more sensitiveto air pollution; understanding the extent of that sensitivity canlead to more effective air quality standards. Also, understanding ofair flow andparticle trajectories could lead to the development of better aerosoldrugs to treat the lung diseases. We focus our efforts on twodiseases: chronic obstructive pulmonary disease (COPD) and bronchialtumors. Because COPD affects the majority of airways in a patientwith the disease, we are able to take a more global approach toanalyzing the effects of the disease. Using a FORTRAN codewhich computes total deposition in the lung over the course of onebreath, we modified the pre-existing code to account forthe difference between healthy subjects and patients with COPD. Usingthe model, itwas possible to isolate the different disease components of COPD andsimulate their effects separately. It was determined thatthe chronic bronchitis component of COPD was responsible for the increaseddeposition seen in COPD patients. While COPD affects the whole lung, tumors tend to belocalized to one or several airways. This led us to investigate theeffects of bronchial tumors in detail within these individualairways. Using a computational fluid dynamics package, FIDAP, wedefined a Weibel type branching network of airways. In particular, we modeled theairways of a four-year-old child. In the work with the tumors, we ran numerous simulations with variousinitial velocities and tumor locations. It was determined that tumorslocated on the carinal ridge had the dominant effect on the flow. Athigher initial velocities, areas of circulation developed downstream from the tumors. Extensive simulations were run with a 2-D model. Theresults from the 2-D model were then compared with some initial 3-Dsimula.
Author: United States. Public Health Service. Office of the Surgeon General
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 728
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Book Description
This report considers the biological and behavioral mechanisms that may underlie the pathogenicity of tobacco smoke. Many Surgeon General's reports have considered research findings on mechanisms in assessing the biological plausibility of associations observed in epidemiologic studies. Mechanisms of disease are important because they may provide plausibility, which is one of the guideline criteria for assessing evidence on causation. This report specifically reviews the evidence on the potential mechanisms by which smoking causes diseases and considers whether a mechanism is likely to be operative in the production of human disease by tobacco smoke. This evidence is relevant to understanding how smoking causes disease, to identifying those who may be particularly susceptible, and to assessing the potential risks of tobacco products.
Author: Ewald R. Weibel
Publisher: Academic Press
ISBN: 1483225798
Category : Computers
Languages : en
Pages : 164
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Book Description
Morphometry of the Human Lung considers the developments in understanding the quantitative anatomy of the lung, and in the correlation of anatomy with physiology. This book is composed of 11 chapters, and begins with an overview of a systematic approach to a quantitative morphologic analysis of the architecture of the human lung, followed by a presentation of general problems of methodology and the derivation of reliable dimensional models of this organ. The subsequent chapters describe the methods of preparation of tissues, methods of random sampling, and adaptation of methodologies from other fields of science. These topics are followed by discussions the mathematical formulations for the translation of the data into the desired geometric forms and a technique of counting. The final chapters look into the mode of distribution and geometric forms that should eventually facilitate mathematical and physical considerations regarding the function of the lungs. These chapters also consider the application of these quantitative methods to the study of pathologic specimens, providing a most timely renovation of morphologic pathology. This book will be of value to pulmonologists, physiologists, and researchers who are interested in lung morphometry.
Author: I. Horvath
Publisher: European Respiratory Society
ISBN: 1849840059
Category : Medical
Languages : en
Pages : 261
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Book Description
Exhaled air contains numerous substances, often in extremely low concentrations. The development of sensitive detection techniques has made it possible to examine the composition of exhaled air in relation to a variety of airway diseases and other disorders. In this book, an overview of current cutting-edge breath analysis techniques and their clinical applications is provided for the clinician. The various contributions give a fascinating perspective of a future where new, highly sensitive methodologies will enable clinicians to diagnose and monitor a wide variety of diseases merely by taking.
Author: Anthony J. Hickey
Publisher: CRC Press
ISBN: 1351660519
Category : Medical
Languages : en
Pages : 546
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Book Description
Inhalation aerosols continue to be the basis for successful lung therapy for several diseases, with therapeutic strategies and the range of technology significantly evolving in recent years. In response, this third edition takes a new approach to reflect the close integration of technology with its application. After briefly presenting the general considerations that apply to aerosol inhalation, the central section of the book uses the focus on disease and therapeutic agents to illustrate the application of specific technologies. The final integrated strategies section draws the major points from the applications for disease targets and drug products.
