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Author: Yingjie Tang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this work, various aerosol particle transport and deposition mechanisms were studied through the computational fluid dynamics (CFD) modeling, including inertial impaction, gravitational effect, lift force, interception, and turbophoresis, within different practical applications including aerosol sampling inlet, filtration system and turbulent pipe flows. The objective of the research is to obtain a better understanding of the mechanisms that affect aerosol particle transport and deposition, and to determine the feasibility and accuracy of using commercial CFD tools in predicting performance of aerosol sampling devices. Flow field simulation was carried out first, and then followed by Lagrangian particle tracking to obtain the aerosol transport and deposition information. The CFD-based results were validated with experimental data and empirical correlations. In the simulation of the aerosol inlet, CFD-based penetration was in excellent agreement with experimental results, and the most significant regional particle deposition occurred due to inertial separation. At higher free wind speeds gravity had less effect on particle deposition. An empirical equation for efficiency prediction was developed considering inertial and gravitational effects, which will be useful for directing design of similar aerosol inlets. In the simulation of aerosol deposition on a screen, a "virtual surface" approach, which eliminates the need for the often-ambiguous user defined functions, was developed to account for particle deposition due to interception. The CFD-based results had a good agreement compared with experimental results, and also with published empirical correlations for interception. In the simulation of turbulent deposition in pipe flows, the relation between particle deposition velocity and wall-normal turbulent velocity fluctuation was quantitative determined for the first time, which could be used to quantify turbulent deposition, without having to carry out Lagrangian particle tracking. It suggested that the Reynolds stress model and large eddy simulation would lead to the most accurate simulated aerosol deposition velocity. The prerequisites were that the wall-adjacent y+ value was sufficiently low, and that sufficient number of prism layers was applied in the near-wall region. The "velocity fluctuation convergence" would be useful criterion for judging the adequacy of a CFD simulation for turbulent deposition.
Author: Yingjie Tang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In this work, various aerosol particle transport and deposition mechanisms were studied through the computational fluid dynamics (CFD) modeling, including inertial impaction, gravitational effect, lift force, interception, and turbophoresis, within different practical applications including aerosol sampling inlet, filtration system and turbulent pipe flows. The objective of the research is to obtain a better understanding of the mechanisms that affect aerosol particle transport and deposition, and to determine the feasibility and accuracy of using commercial CFD tools in predicting performance of aerosol sampling devices. Flow field simulation was carried out first, and then followed by Lagrangian particle tracking to obtain the aerosol transport and deposition information. The CFD-based results were validated with experimental data and empirical correlations. In the simulation of the aerosol inlet, CFD-based penetration was in excellent agreement with experimental results, and the most significant regional particle deposition occurred due to inertial separation. At higher free wind speeds gravity had less effect on particle deposition. An empirical equation for efficiency prediction was developed considering inertial and gravitational effects, which will be useful for directing design of similar aerosol inlets. In the simulation of aerosol deposition on a screen, a "virtual surface" approach, which eliminates the need for the often-ambiguous user defined functions, was developed to account for particle deposition due to interception. The CFD-based results had a good agreement compared with experimental results, and also with published empirical correlations for interception. In the simulation of turbulent deposition in pipe flows, the relation between particle deposition velocity and wall-normal turbulent velocity fluctuation was quantitative determined for the first time, which could be used to quantify turbulent deposition, without having to carry out Lagrangian particle tracking. It suggested that the Reynolds stress model and large eddy simulation would lead to the most accurate simulated aerosol deposition velocity. The prerequisites were that the wall-adjacent y+ value was sufficiently low, and that sufficient number of prism layers was applied in the near-wall region. The "velocity fluctuation convergence" would be useful criterion for judging the adequacy of a CFD simulation for turbulent deposition.
Author: Geng Tian
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages :
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Book Description
Predicting vapor transport and aerosol dynamics in the respiratory airways is important for analyzing both environmental exposure and respiratory drug delivery. A large number of analytical models, computational studies, and experiments on vapor and aerosol transport in the respiratory tract have been conducted previously. However, a number of critical questions remain unanswered. In this study, computational fluid dynamics (CFD) is primarily employed with frequent comparisons to existing and new experimental data sets to address previously unanswered issues related to the transport of vapors and aerosol in the respiratory tract. The three objectives of this study are further described below. Objective 1: A CFD model was developed to predict the transient absorption of inhaled vapors in the respiratory tract. Results indicated that transient absorption can significantly influence the transport and uptake of vapors in the walls of the conducting airways. Objective 2: The concept of enhanced condensational growth (ECG) applied to respiratory drug delivery was tested in a representative airway model extending from the oral cavity to the end of the tracheobronchial (TB) airways. Results indicated that ECG is an effective method to provide near full lung retention of the aerosol. The CFD results also indicated that the ECG delivery approach under transient inhalation conditions increased aerosol deposition in the TB airways by only a small amount, as compared with steady state conditions. Objective 3: The effect of transient waveforms on the transport and deposition of pharmaceutical aerosols from inhalers in the upper airways was considered. Results indicated that the CFD model predictions matched the in vitro experiments to a high degree. The CFD results also indicated that it was critical to consider transient inhalation effects when assessing aerosol deposition. The stochastic individual path (SIP) modeling approach was then introduced and implemented to evaluate the transport and deposition of pharmaceutical aerosols from inhalers in medium and small TB airways. Results indicated that steady state inhalation could be used to predict deposition efficiencies in the TB airways between the 4th branch (B4) and the bronchioles (B15).
Author: Jiyuan Tu
Publisher: Springer Science & Business Media
ISBN: 9400744889
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: Ted B. Martonen
Publisher: Witpress
ISBN:
Category : Computers
Languages : en
Pages : 376
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Book Description
Designed for use in both academic and research environments, this volume addresses applications of computer modelling and fluid dynamics to biological systems. Emphasis is placed on demonstrating the important roles that mathematical theory and computer technology play in the medical arena. This text focuses on the respiratory system and includes such topics as morphology of the human extrathoracic airways, the morphology of the lung and stochastic modelling of particle deposition in the human lung.
Author: Anthony J. Hickey
Publisher: CRC Press
ISBN: 1351660527
Category : Medical
Languages : en
Pages : 417
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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.
Author: Samir C. Vinchurkar
Publisher:
ISBN:
Category : Aerosol therapy
Languages : en
Pages : 470
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Book Description
The dynamics of particle laden flows are integral to the analysis of toxic particle deposition and medical respiratory aerosol delivery. Computational fluid-particle dynamics (CFPD) can play a critical role in developing a better understanding of particle laden flows, especially in a number of under-explored areas. The applications considered in this study include both the numerical aspects and the physical phenomena of respiratory aerosol transport. Objective I: Considering the effects of mesh type and grid convergence, four commonly implemented mesh styles were applied to a double bifurcation respiratory geometry and tested for flow patterns and aerosol deposition. Results indicated that the mesh style employed had a significant effect on the transport and deposition of aerosols with hexahedral meshes being most accurate. Objective II: In order to evaluate the effects of bronchoconstriction under exhalation conditions, normal and constricted pediatric airway models were considered. Results include (i) a significant increase in deposition for constricted airways, and (ii) a novel correlation for deposition during exhalation based on the Dean and Stokes numbers. Objective IIIa: Considering evaluation of an aerosol size sampler, an eight-stage Andersen cascade impactor (ACI) was numerically analyzed. The numerical simulations indicated high non-uniformity and recirculation in the flow field. Numerical predictions of retention fraction matched well with existing experiments (0.5 - 11% error). Objective IIIb: As an extension to this study, numerical predictions of electrostatic charge effects on aerosol transport and deposition in the ACI were presented. Charges consistent with standard pharmaceutical pressurized metered dose inhalers and dry powder inhalers were considered. The numerical predictions indicated that charged aerosols deposit as if they were 5 - 85% larger due to electrostatic effects. Applications of the studies considered include (i) quantitative guidance in selecting numerical mesh styles and development of standard grid convergence criteria, (ii) the development of more accurate whole-lung deposition models that better evaluate exhalation conditions, (iii) improvements in the design of pharmaceutical assessment and delivery devices, and (vi) correction values to account for electrostatic charge on pharmaceutical aerosols.
Author: Ryoichi Amano
Publisher: WIT Press
ISBN: 1845641442
Category : Technology & Engineering
Languages : en
Pages : 513
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Book Description
Heat transfer and fluid flow issues are of great significance and this state-of-the-art edited book with reference to new and innovative numerical methods will make a contribution for researchers in academia and research organizations, as well as industrial scientists and college students. The book provides comprehensive chapters on research and developments in emerging topics in computational methods, e.g., the finite volume method, finite element method as well as turbulent flow computational methods. Fundamentals of the numerical methods, comparison of various higher-order schemes for convection-diffusion terms, turbulence modeling, the pressure-velocity coupling, mesh generation and the handling of arbitrary geometries are presented. Results from engineering applications are provided. Chapters have been co-authored by eminent researchers.
Author: Nikolai V. Brilliantov
Publisher: Oxford University Press
ISBN: 0199588139
Category : Science
Languages : en
Pages : 343
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Book Description
In contrast to molecular gases (for example, air), the particles of granular gases, such as a cloud of dust, lose part of their kinetic energy when they collide, giving rise to many exciting physical properties. The book provides a self-contained introduction to the theory of granular gases for advanced undergraduates and beginning graduates.
Author: Mamoru Ishii
Publisher: Springer Science & Business Media
ISBN: 0387291873
Category : Technology & Engineering
Languages : en
Pages : 462
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Book Description
This book has been written for graduate students, scientists and engineers who need in-depth theoretical foundations to solve two-phase problems in various technological systems. Based on extensive research experiences focused on the fundamental physics of two-phase flow, the authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to a variety of scenarios, including nuclear reactor transient and accident analysis, energy systems, power generation systems and even space propulsion.
Author: Clive A.J. Fletcher
Publisher: Springer Science & Business Media
ISBN: 364258229X
Category : Science
Languages : en
Pages : 412
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Book Description
This well-known 2-volume textbook provides senior undergraduate and postgraduate engineers, scientists and applied mathematicians with the specific techniques, and the framework to develop skills in using the techniques in the various branches of computational fluid dynamics. A solutions manual to the exercises is in preparation.
