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Author: Rafael Mattos dos Santos Publisher: ISBN: 9780494400630 Category : Languages : en Pages : 113
Book Description
Gas-liquid two-phase flow in a microfluidic T-junction with nearly square microchannels of 113 mum hydraulic diameter was investigated experimentally and numerically. Air and water superficial velocities were 0.018-0.791 m/s and 0.042-0.757 m/s, respectively. Three-dimensional modeling was performed with computational fluid dynamics (CFD) package FLUENT and the volume-of-fluid (VOF) model. 3D modeling resolved surface tension effects more accurately than 2D simulation. Slug flow (snapping/breaking/jetting) and stratified flow were observed experimentally. From numerical results void fraction followed a linear relationship with the homogeneous void fraction; two-phase frictional pressure drop fitted the Lockhart-Martinelli correlation with a Chisholm constant of 5; and the contact angle value affected the shape and size of gas slugs and determined the occurrence of liquid film and corner flow. Correlations were developed for prediction of flow parameters. Higher experimental velocity slip caused by gas inlet pressure build-up can result in deviation from numerical predictions.
Author: Rafael Mattos dos Santos Publisher: ISBN: 9780494400630 Category : Languages : en Pages : 113
Book Description
Gas-liquid two-phase flow in a microfluidic T-junction with nearly square microchannels of 113 mum hydraulic diameter was investigated experimentally and numerically. Air and water superficial velocities were 0.018-0.791 m/s and 0.042-0.757 m/s, respectively. Three-dimensional modeling was performed with computational fluid dynamics (CFD) package FLUENT and the volume-of-fluid (VOF) model. 3D modeling resolved surface tension effects more accurately than 2D simulation. Slug flow (snapping/breaking/jetting) and stratified flow were observed experimentally. From numerical results void fraction followed a linear relationship with the homogeneous void fraction; two-phase frictional pressure drop fitted the Lockhart-Martinelli correlation with a Chisholm constant of 5; and the contact angle value affected the shape and size of gas slugs and determined the occurrence of liquid film and corner flow. Correlations were developed for prediction of flow parameters. Higher experimental velocity slip caused by gas inlet pressure build-up can result in deviation from numerical predictions.
Author: Publisher: ISBN: Category : Languages : en Pages : 110
Book Description
During the course of this research effort gas flows in microchannels and micronozzles were studied both experimentally and numerically. For the experimental study a flow visualization system was built and used to Study gas flows in microscale. Gas velocity measurements in microscope were conducted using both Laser Induced Fluorescence technique in conjunction with Image Correlation Velocimetry and Molecular Tagging Velocimetry technique. For the numerical study three different approaches were utilized. Continuum computational fluid dynamics was first used to study gas flows in microchannels and micronozzles. For micronozzles, effects of geometrical scaling down and different gas propellants were studied. For microchannels, slip versus no-slip boundary condition and compressibility and rarefaction effects were studied. Secondly, Direct simulation Monte Carlo (DSMC) method was used to study low Reynolds number flows in a conical micronozzle. The DSMC simulations were compared with the continuum model and available experimental data, and also used to study propellant gas temperature effect on the generated thrust Thirdly, a Unified Flow Solver that utilizes hybrid approach using deterministic Boltzmann solver for highly non-equilibrium flows at high Knudsen number and continuum solvers for low Knudsen numbers was tested and demonstrated for gas flows in microscale. Tested cases included gas flows in both microchannels and micronozzles.
Author: S. Mostafa Ghiaasiaan Publisher: Cambridge University Press ISBN: 1316785300 Category : Technology & Engineering Languages : en Pages : 1322
Book Description
Providing a comprehensive introduction to the fundamentals and applications of flow and heat transfer in conventional and miniature systems, this fully enhanced and updated edition covers all the topics essential for graduate courses on two-phase flow, boiling, and condensation. Beginning with a concise review of single-phase flow fundamentals and interfacial phenomena, detailed and clear discussion is provided on a range of topics, including two-phase hydrodynamics and flow regimes, mathematical modeling of gas-liquid two-phase flows, pool and flow boiling, flow and boiling in mini and microchannels, external and internal-flow condensation with and without noncondensables, condensation in small flow passages, and two-phase choked flow. Numerous solved examples and end-of-chapter problems that include many common design problems likely to be encountered by students, make this an essential text for graduate students. With up-to-date detail on the most recent research trends and practical applications, it is also an ideal reference for professionals and researchers in mechanical, nuclear, and chemical engineering.
Author: Jurij Gregorc (strojnik.) Publisher: ISBN: Category : Languages : en Pages : 181
Book Description
The two-phase flow phase separation in a mini-manifold composed of three consecutive T-junctions was studied. Measurements were conducted over wide range of gas-liquid flow rates. The following discernible flow regimes were considered: bubbly, bubbly to slug, slug, semi-annular, and churn flow. Systematic separation trends were observed, depending upon flow pattern in front of T-junction. Numerical modeling was chosen to predict the two-phase flow separation effects in a mini manifold using VOF technique. First, an algorithm to include initial conditions, enabling prediction of relevant interfacial flow structures was needed. In order to develop such an algorithm, experiments were conducted on mini-tube test section. Experimental observations gave clues regarding flow pattern formation. These insights were used to mimic experimental inlet conditions numerically. The proposed initial conditions algorithm enables prediction of different flow patterns changing only the prescribed flow rates. The validation was done against mini-tube experimental observations and showed promising results even when trying to predict bubble to slug flow transition. The initial conditions algorithm was applied to phase separation simulation in case of bubbly and slug flow. Reasonable agreement with experimental data was ascertained, giving good basis to study the balance of forces at the T-junction which governs the phase separation.
Author: Chao Yang Publisher: Academic Press ISBN: 0124115799 Category : Technology & Engineering Languages : en Pages : 322
Book Description
Numerical simulation of multiphase reactors with continuous liquid phase provides current research and findings in multiphase problems, which will assist researchers and engineers to advance this field. This is an ideal reference book for readers who are interested in design and scale-up of multiphase reactors and crystallizers, and using mathematical model and numerical simulation as tools. Yang and Mao’s book focuses on modeling and numerical applications directly in the chemical, petrochemical, and hydrometallurgical industries, rather than theories of multiphase flow. The content will help you to solve reacting flow problems and/or system design/optimization problems. The fundamentals and principles of flow and mass transfer in multiphase reactors with continuous liquid phase are covered, which will aid the reader’s understanding of multiphase reaction engineering. Provides practical applications for using multiphase stirred tanks, reactors, and microreactors, with detailed explanation of investigation methods Presents the most recent research efforts in this highly active field on multiphase reactors and crystallizers Covers mathematical models, numerical methods and experimental techniques for multiphase flow and mass transfer in reactors and crystallizers
Author: Santiago Arias Calderon Publisher: ISBN: Category : Languages : en Pages : 164
Book Description
Promising technological applications of two-phase flows in space have captured the increasing interest of the space sector, provoking a strong demand for more fundamental knowledge. Great efforts have been made in recent decades to study the behavior of two-phase flows in low-gravity environments, which is expected to be different than the behavior observed in the presence of gravitational forces. Nevertheless, many phenomena are still poorly understood. The development of any of these new technologies demands a better knowledge of two-phase flows. In this manuscript we address questions regarding the generation of gas-liquid flows and their behavior in conditions relevant for a microgravity environment. In particular, we focus on an air-water mixture formed in a capillary T-junction. To this end, an experimental setup has been designed to accurately control both gas and liquid flow rates. We performed a quantitative characterization on ground of the T-junction, whose operation is robust to changes in gravity level. Its main performance is the generation of bubbles at a regular frequency with small size dispersion. We obtained two working regimes of the T-junction and identified the crossover region between them. Bubble, slug, churn and annular flow regimes have been observed during the experiments and a flow pattern map has been plotted. We present an experimental study on the bubble-slug transition in microgravity-related conditions. In addition, we address questions regarding the existence of a critical void fraction in order for the bubble-slug transition to occur. The gas-liquid flow has been characterized by measuring the bubble generation frequency as well as the bubble and liquid slug sizes. Since bubble dynamics is also expected to be different in the absence of buoyancy, the bubble velocity has also been studied. The mean void fraction appears as one relevant parameter that allows for the prediction of frequency, bubble velocity, and lengths. We propose curves obtained empirically for the behavior of generation frequency, the bubble velocity and the lengths. The dependence of the frequency on the Strouhal dimensionless number has been analyzed. A numerical study of the formation of mini-bubbles in a 2D T-junction by means of the fluid dynamics numerical code JADIM is also presented. Simulations were carried out for different flow conditions, giving rise to results on the bubble generation frequency, bubble velocity, void fraction and characteristic lengths. Numerical results have been then compared with experimental data.
Author: Bengt Sunden Publisher: MDPI ISBN: 3039364936 Category : Technology & Engineering Languages : en Pages : 334
Book Description
In recent years, microfluidic devices with a large surface-to-volume ratio have witnessed rapid development, allowing them to be successfully utilized in many engineering applications. A smart control process has been proposed for many years, while many new innovations and enabling technologies have been developed for smart flow control, especially concerning “smart flow control” at the microscale. This Special Issue aims to highlight the current research trends related to this topic, presenting a collection of 33 papers from leading scholars in this field. Among these include studies and demonstrations of flow characteristics in pumps or valves as well as dynamic performance in roiling mill systems or jet systems to the optimal design of special components in smart control systems.
Author: Mohamed Sultan Mohamed Ali Publisher: Springer ISBN: 9811064636 Category : Computers Languages : en Pages : 752
Book Description
This two-volume set CCIS 751 and CCIS 752 constitutes the proceedings of the 17th Asia Simulation Conference, AsiaSim 2017, held in Malacca, Malaysia, in August/September 2017. The 124 revised full papers presented in this two-volume set were carefully reviewed and selected from 267 submissions. The papers contained in these proceedings address challenging issues in modeling and simulation in various fields such as embedded systems; symbiotic simulation; agent-based simulation; parallel and distributed simulation; high performance computing; biomedical engineering; big data; energy, society and economics; medical processes; simulation language and software; visualization; virtual reality; modeling and Simulation for IoT; machine learning; as well as the fundamentals and applications of computing.
Author: Mohammad Taeibi Rahni Publisher: CRC Press ISBN: 1498722091 Category : Science Languages : en Pages : 549
Book Description
Computational Methods for Complex Liquid-Fluid Interfaces highlights key computational challenges involved in the two-way coupling of complex liquid-fluid interfaces. The book covers a variety of cutting-edge experimental and computational techniques ranging from macro- to meso- and microscale approaches (including pivotal applications). As example
Author: Nam-Trung Nguyen Publisher: Integrated Microsystems ISBN: 9781630813642 Category : Fluidic devices Languages : en Pages : 0
Book Description
Now in its Third Edition, the Artech House bestseller, Fundamentals and Applications of Microfluidics, provides engineers and students with the most complete and current coverage of this cutting-edge field. This revised and expanded edition provides updated discussions throughout and features critical new material on microfluidic power sources, sensors, cell separation, organ-on-chip and drug delivery systems, 3D culture devices, droplet-based chemical synthesis, paper-based microfluidics for point-of-care, ion concentration polarization, micro-optofluidics and micro-magnetofluidics. The book shows how to take advantage of the performance benefits of microfluidics and serves as an instant reference for state-of-the-art microfluidics technology and applications. Readers find discussions on a wide range of applications, including fluid control devices, gas and fluid measurement devices, medical testing equipment, and implantable drug pumps. Professionals get practical guidance in choosing the best fabrication and enabling technology for a specific microfluidic application, and learn how to design a microfluidic device. Moreover, engineers get simple calculations, ready-to-use data tables, and rules of thumb that help them make design decisions and determine device characteristics quickly. addressed at the design stage to reduce the risk of failures in the field is presented. The book includes technical details of all state-of-the-art Li-on energy storage subsystems and their requirements, and provides a system designer a single resource detailing all of the common issues navigated when using Li-ion batteries to reduce the risk of field failures. The book details the various industry standards that are applicable to the subsystems of Li-ion energy storage systems and how the requirements of these standards may impact the design of their system. Checklists are included to help readers evaluate their own battery system designs and identify gaps in the designs that increase the risk of field failures. The book is packed with numerous examples of issues that have caused field failures and how a proper design/assembly process could have reduced the risk of these failures.
Author: Rafael Mattos dos Santos
Author: Rafael Mattos dos Santos
Author: 
Author: S. Mostafa Ghiaasiaan
Author: Jurij Gregorc (strojnik.)
Author: Chao Yang
Author: Santiago Arias Calderon
Author: Bengt Sunden
Author: Mohamed Sultan Mohamed Ali
Author: Mohammad Taeibi Rahni
Author: Nam-Trung Nguyen