Comparison of Particle Deposition for Realistic Adult and Adolescent Upper Airway Geometries Using Unsteady Computational Fluid Dynamics PDF Download
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Author: Jonathan Steffens
Publisher:
ISBN:
Category : Atmospheric deposition
Languages : en
Pages : 230
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Book Description
"Particle deposition in the respiratory tract is studied in order to better understand the negative health effects due to cigarette smoke inhalation. Until recently, idealized models of the respiratory airways based on the original Weibel model have been used to calculate deposition. These models consist of symmetric bifurcating airways and do not take into account variations of airway diameter, and asymmetry in the human respiratory tract. Until recently, little work has been done to accurately recreate the entire upper respiratory tract including the oral cavity, pharynx, and larynx. Technological improvement has changed the way in which researchers approach this problem. With the advent of high resolution scans of the respiratory tract, accurate replica models can be created to better predict cigarette smoke particle (CSP) deposition. These models recreate actual lung geometries found in patients. For this thesis, two realistic geometric models are created. One is based on an adult male and the other on an adolescent male. CSP deposition is determined for both models in order to compare the difference cased by age in smoking. In addition, an unsteady breathing curve, indicative of realistic smoking behavior is utilized to more accurately represent the breathing conditions. Both models consist of the oral cavity, throat, larynx, trachea, and first five to seven generations of the lungs. The adult model is based on a dental cast of the mouth, a CT scan of the throat and larynx, and images based on the National Institute of Health's Visible Human Project for the tracheobronchial tree. The adolescent model is based upon a scaled oral cavity and CT scans of the rest of the reparatory tract. The program 3D Doctor is used to reconstruct the two dimensional CT scan images into a three dimensional model. VPSculpt and SolidWorks are used to combine the different parts of the models and clean up the geometry. The geometry is meshed in Gambit and exported to the Computational Fluid Dynamics (CFD) software package Fluent to perform the fluid flow and particle deposition analysis. The Fluent Discrete Phase Model (DPM) is used to determine particle trajectories and deposition. It is found that deposition increases with the size of the inhaled particles. Particles tend to deposit towards the back of the throat, the area of the trachea just below the glottis, and at bifurcations in the airways. However, when compared to other studies in literature, deposition tended to be higher with smaller particle sizes, but more comparable with larger particle sizes. Adolescent deposition was found to be lower than adult deposition for all particle sizes."--Abstract.
Author: Jonathan Steffens
Publisher:
ISBN:
Category : Atmospheric deposition
Languages : en
Pages : 230
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Book Description
"Particle deposition in the respiratory tract is studied in order to better understand the negative health effects due to cigarette smoke inhalation. Until recently, idealized models of the respiratory airways based on the original Weibel model have been used to calculate deposition. These models consist of symmetric bifurcating airways and do not take into account variations of airway diameter, and asymmetry in the human respiratory tract. Until recently, little work has been done to accurately recreate the entire upper respiratory tract including the oral cavity, pharynx, and larynx. Technological improvement has changed the way in which researchers approach this problem. With the advent of high resolution scans of the respiratory tract, accurate replica models can be created to better predict cigarette smoke particle (CSP) deposition. These models recreate actual lung geometries found in patients. For this thesis, two realistic geometric models are created. One is based on an adult male and the other on an adolescent male. CSP deposition is determined for both models in order to compare the difference cased by age in smoking. In addition, an unsteady breathing curve, indicative of realistic smoking behavior is utilized to more accurately represent the breathing conditions. Both models consist of the oral cavity, throat, larynx, trachea, and first five to seven generations of the lungs. The adult model is based on a dental cast of the mouth, a CT scan of the throat and larynx, and images based on the National Institute of Health's Visible Human Project for the tracheobronchial tree. The adolescent model is based upon a scaled oral cavity and CT scans of the rest of the reparatory tract. The program 3D Doctor is used to reconstruct the two dimensional CT scan images into a three dimensional model. VPSculpt and SolidWorks are used to combine the different parts of the models and clean up the geometry. The geometry is meshed in Gambit and exported to the Computational Fluid Dynamics (CFD) software package Fluent to perform the fluid flow and particle deposition analysis. The Fluent Discrete Phase Model (DPM) is used to determine particle trajectories and deposition. It is found that deposition increases with the size of the inhaled particles. Particles tend to deposit towards the back of the throat, the area of the trachea just below the glottis, and at bifurcations in the airways. However, when compared to other studies in literature, deposition tended to be higher with smaller particle sizes, but more comparable with larger particle sizes. Adolescent deposition was found to be lower than adult deposition for all particle sizes."--Abstract.
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: Taylor Steven Geisler
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Prolonged exposure to inhaled micron-sized airborne particles is a known public health concern. These particles impact the health of staggering numbers of residents of polluted urban areas, as well as significant portions of the third world where it is still common to burn wood or charcoal indoors for cooking or heating. An understanding of the fate of inhaled particles in the lungs is useful for assessing their associated health risks, as well as improving the effectiveness of respiratory drug delivery techniques. The transport of microparticles is inseparable from behavior of the suspending airflow and this is studied using computational fluid dynamics techniques. The anatomy of the airways seems to have evolved to encourage turbulent airflow for functions such as mixing of flow to promote the warming and humidification of inhaled air, as well as for filtration. Large eddy simulation models are employed to capture turbulent flow in extremely complex patient-specific airway geometries. These collectively comprise the oral and nasal cavities, larynx, trachea, and the bronchial tree. The flow in anatomically-accurate rhesus macaque airways is also studied. Simulations are carried out for inspiratory flow rates corresponding to nominal Reynolds numbers in the hundreds to low-thousands yet somewhat surprisingly yield unsteady flows due to local geometric factors. A computed mean flow field is compared extensively with magnetic resonance velocimetry measurements carried out in the same computed-tomography--based lung geometry, showing good agreement. Microparticle deposition predictions are also verified. Focus is placed on the dynamics of the flow in the nasal airway, trachea, and bronchial tree. After becoming unsteady at constrictions in the upper airways, the flow is found to be chaotic, exhibiting fluctuations with broad-band spectra even at the most distal simulated airways in which the Reynolds numbers are as low as 300. The unsteadiness is attributed to the convection of turbulent structures produced in the upper airways as well as to local kinetic energy production throughout the bronchial tree.
Author: Goutham Mylavarapu
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
Computational modeling of biological systems have gained a lot of interest in biomedical research, in the recent past. This thesis focuses on the application of computational simulations to study airflow dynamics in human upper respiratory tract. With advancements in medical imaging, patient specific geometries of anatomically accurate respiratory tracts can now be reconstructed from Magnetic Resonance Images (MRI) or Computed Tomography (CT) scans, with better and accurate details than traditional cadaver cast models. Computational studies using these individualized geometrical models have advantages of non-invasiveness, ease, minimum patient interaction, improved accuracy over experimental and clinical studies. Numerical simulations can provide detailed flow fields including velocities, flow rates, airway wall pressure, shear stresses, turbulence in an airway. Interpretation of these physical quantities will enable to develop efficient treatment procedures, medical devices, targeted drug delivery etc. The hypothesis for this research is that computational modeling can predict the outcomes of a surgical intervention or a treatment plan prior to its application and will guide the physician in providing better treatment to the patients. In the current work, three different computational approaches Computational Fluid Dynamics (CFD), Flow-Structure Interaction (FSI) and Particle Flow simulations were used to investigate flow in airway geometries. CFD approach assumes airway wall as rigid, and relatively easy to simulate, compared to the more challenging FSI approach, where interactions of airway wall deformations with flow are also accounted. The CFD methodology using different turbulence models is validated against experimental measurements in an airway phantom. Two case-studies using CFD, to quantify a pre and post-operative airway and another, to perform virtual surgery to determine the best possible surgery in a constricted airway is demonstrated. The unsteady Large Eddy simulations (LES) and a steady Reynolds Averaged Navier Stokes (RANS) approaches in CFD modeling are discussed. The more challenging FSI approach is modeled first in simple two-dimensional anatomical geometry and then extended to simplified three dimensional geometry and finally in three dimensionally accurate geometries. The concepts of virtual surgery and the differences to CFD are discussed. Finally, the influence of various drug delivery parameters on particle deposition efficiency in airway anatomy are investigated through particle-flow simulations in a nasal airway model.
Author: Azadeh Akhavan Taheri Borojeni
Publisher:
ISBN:
Category : Aerosol therapy
Languages : en
Pages : 90
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Book Description
One objective of this research was to obtain a correlation that quantitatively predicts micrometer-sized aerosol particle deposition in the upper conducting airways (trachea to generation 3) of children. Experiments were conducted using steady inhalation air flow rates to measure the deposition of monodisperse particles with diameters of 3.5-5.5 micro-meter in replicas of the upper tracheobronchial airways of 11 children aged 2-8 years. The total deposition of particles was measured in each replica using gravimetry. Validation was performed by measuring deposition in five adult replicas and comparing with existing published data. Although there is considerable intersubject variability in our data, the empirical correlation of Chan & Lippmann (1980) was found to predict total deposition reasonably well in all of our adult and child replicas. A second goal of this study was to design an idealized pediatric central conducting airway model that mimics average total particle deposition in the airways of 4-8 year old children. Dimensions of the idealized model were selected based on analytical prediction of deposition in scaled versions of existing adult airway geometries. Validation experiments were then conducted using steady inhalation air flow rate to measure the deposition of monodisperse particles with mass median diameters (MMD) of 3.5, 4.5, 5 and 5.2 micro-meter in the idealized pediatric model. The total deposition of particles was measured using gravimetry. Experimental data confirmed that aerosol deposition in the idealized pediatric central conducting airway geometry was consistent with the average deposition previously measured in 10 realistic airway replicas for children 4-8 years old. Finally, this thesis describes in vitro measurements of the total pressure loss at varying flow rate through anatomically realistic conducting airway replicas of ten children, 4 to 8 years old, and five adults. Experimental results were compared with analytical predictions made using published airway resistance models. For the adult replicas, the model proposed by van Ertbruggen et al. (J. Appl. Physiol. 98:970-980,2005) most accurately predicted central conducting airway resistance for inspiratory flow rates ranging from 15 to 90 L/min. Models proposed by Pedley et al. (J. Respir. Physiol. 9:371-386,1970) and by Katz et al. (J. Biomechanics 44:1137-1143,2011) also provided reasonable estimates, but with a tendency to over predict measured pressure loss for both models. For child replicas, the Pedley and Katz models both provided good estimation of measured pressure loss at flow rates representative of resting tidal breathing, but under predicted measured values at high inspiratory flow rate (60 L/min). The van Ertbruggen model, developed based on flow simulations performed in an adult airway model, tended to under predict measured pressure loss through the child replicas across the range of flow rates studied (2 to 60 L/min). These results are intended to provide guidance for selection of analytical pressure loss models for use in predicting airway resistance and ventilation distribution in adults and children.
Author: Michael J. Oldham
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 314
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Book Description
Author: René Pomeau
Publisher:
ISBN: 9780729404938
Category :
Languages : en
Pages : 876
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Book Description
Author: James D. Crapo
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 400
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Book Description
Extrapolation Modeling, Advancements and Research Issues in Lung Dosimetry; Lung Structure, Function Relationships; Species Differences in Airway Cell Distribution and Morphology; Alternative Methods to Evaluate Species Differences in Upper Airway Structure, Function; Preparation of Rat Nasal Airway Casts and Their Application to Studies of Nasal Airflow; Age Related Morphometric Analysis of Human Lung Casts; Anatomical Modeling of Microdosimetry of Inhaled Particles and Gases in the Lung; Experimental Dosimetry; Particle Deposition at the Alveolar Duct Bifurcations; Effects of Airway Branch Angle, Branch Point Number, and Gravity on Particle Deposition and Retention; Regional Deposition of Inhaled Particulates in Conducting Airways and Lung Segments; The Physical Properties of Mainstream Cigarette Smoke and Their Relationship to Deposition in the Respiratory Tract; Localization of 14C Dotriacontane Labeled Cigarette Smoke Particulate in the Dog Lung; Human Lung Clearance Following Bolus Inhalation of Radioaerosols; Effects of Ventilatory Patterns and Pre-existing Disease on Deposition of Inhaled Particles in Animals; Nasopharyngeal Uptake of Ozone in Humans and Animals; New Methods; Regional Dosimetry of Inhaled Particles Using SPECT; Dual Laser Doppler System for Real Time, Simultaneous Characterization of Aerosols by Size and Concentration; Dosimetry of Inhaled Particles by Means of Light Scattering; Modeling Approaches; Issues That Must Be Addressed When Constructing Anatomical Models of the Developing Lung; Significances of the Variability of Tracheobronchial Airway Paths and Their Air Flow Rates to Dosimetry Model Predictions of the Absorption of Gases; Predicting Respiratory Tract Clearance in Man; The Role of Particle Hygroscopicity in Aerosol Therapy and Inhalation Toxicology; Age-Dependent Lung Dosimetry of Radon Progeny; Deposition and Retention Modeling of Inhaled Cadmium in Rat and Human Lung, An Example for Extrapolation of Effects and Risk Estimation.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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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
