Download or read book Turbulence Modulation in Gas particle Flows a Comparison of Selected Models written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulence Modulation in Gas particle Flows a Comparison of Selected Models written by Sarah M. Hodgson and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of turbulence modulation, the process whereby the gas-phase turbulence is modified by the presence of particles, is investigated. Experimental trends are examined and parameters affecting turbulence modulation and the mechanisms by which turbulence modulation occurs are identified. A new model that accounts for the crossing trajectory effect is presented. This model and the turbulence modulation models of Chen and Wood [4], Tu and Fletcher [45], and Mostafa and Mongia [30] are investigated using the TASCflow CFD code. The models are compared with the experimental results of Tsuji et al [44]. The model of Tu and Fletcher is not able to reproduce either general experimental trends or the experimental results, while the other three models can predict the general experimental trends but cannot reproduce the experimental results. Analysis shows that the turbulent viscosity, [mu]'t', plays an important role in modifying the turbulence intensity profiles. The new model was not able to capture the crossing trajectory effect for the flow considered.
Download or read book Communcations and Information Processing written by Maotai Zhao and published by Springer. This book was released on 2012-06-28 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two volume set, CCIS 288 and 289, constitutes the thoroughly refereed post-conference proceedings of the First International Conference on Communications and Information Processing, ICCIP 2012, held in Aveiro, Portugal, in March 2012. The 168 revised full papers of both volumes were carefully reviewed and selected from numerous submissions. The papers present the state-of-the-art in communications and information processing and feature current research on the theory, analysis, design, test and deployment related to communications and information processing systems.
Download or read book CJChE written by and published by . This book was released on 2004-02 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Computer Science and Education Applications written by Mark Zhou and published by Springer Science & Business Media. This book was released on 2011-06-30 with total page 607 pages. Available in PDF, EPUB and Kindle. Book excerpt: This two-volume set (CCIS 201 and CCIS 202) constitutes the refereed proceedings of the International Conference on Computer Science and Education, CSE 2011, held in Qingdao, China, in July 2011. The 164 revised full papers presented in both volumes were carefully reviewed and selected from a large number of submissions. The papers address a large number of research topics and applications: from artificial intelligence to computers and information technology; from education systems to methods research and other related issues; such as: database technology, computer architecture, software engineering, computer graphics, control technology, systems engineering, network, communication, and other advanced technology, computer education, and life-long education.
Download or read book Dilute Turbulent Gas solid Flow with Particle Interactions and Turbulence Modulation written by Eduardo Jose Bolio and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Engineering Turbulence Modelling and Experiments 5 written by W. Rodi and published by Elsevier. This book was released on 2002-08-21 with total page 1029 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends increasingly on the performance of the turbulence models. This series of symposia provides a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. The papers in this set of proceedings were presented at the 5th International Symposium on Engineering Turbulence Modelling and Measurements in September 2002. They look at a variety of areas, including: Turbulence modelling; Direct and large-eddy simulations; Applications of turbulence models; Experimental studies; Transition; Turbulence control; Aerodynamic flow; Aero-acoustics; Turbomachinery flows; Heat transfer; Combustion systems; Two-phase flows. These papers are preceded by a section containing 6 invited papers covering various aspects of turbulence modelling and simulation as well as their practical application, combustion modelling and particle-image velocimetry.
Download or read book Predictive Modeling of Particle laden Turbulent Flows written by and published by . This book was released on 1992 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The successful prediction of particle-laden, turbulent flows relies heavily on the representation of turbulence in the gas phase. Several types of turbulence models for single-phase gas flow have been developed which compare reasonably well with experimental data. In the present work, a low-Reynolds'' k-[epsilon], closure model is chosen to describe the Reynolds stresses associated with gas-phase turbulence. This closure scheme, which involves transport equations for the turbulent kinetic energy and its dissipation rate, is valid in the turbulent core as well as the viscous sublayer. Several versions of the low-Reynolds k-[epsilon] closure are documented in the literature. However, even those models which are similar in theory often differ considerably in their quantitative and qualitative predictions, making the selection of such a model a difficult task. The purpose of this progress report is to document our findings on the performance of ten different versions of the low-Reynolds k-[epsilon] model on predicting fully developed pipe flow. The predictions are compared with the experimental data of Schildknecht, et al. (1979). With the exception of the model put forth by Hoffman (1975), the predictions of all the closures show reasonable agreement for the mean velocity profile. However, important quantitative differences exist for the turbulent kinetic energy profile. In addition, the predicted eddy viscosity profile and the wall-region profile of the turbulent kinetic energy dissipation rate exhibit both quantitative and qualitative differences. An effort to extend the present comparisons to include experimental measurements of other researchers is recommended in order to further evaluate the performance of the models.
Download or read book Turbulence Modulation in Particle laden Flows written by John D. Schwarzkopf and published by . This book was released on 2008 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Turbulence Modulation by Finite size Solid Particles with the Lattice Boltzmann Method written by Cheng Peng and published by . This book was released on 2018 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent flows laden with finite-size solid particles are found in a variety of natural and engineering processes. However, the overall understanding of how the flow properties, such as turbulent intensity and flow drag, are modified by the addition of the particles is still limited. So far, the only rigorous approach to investigate the modulation mechanisms at the particle scale is to numerically solve the disturbance flow around each particle, known as the interface-resolved simulations (IRS). However, the application of IRS in the turbulent particle-laden flow is particularly challenging due to the requirements of resolving all the length and time scales in the turbulent flow, as well as the need to realize the no-slip boundary condition on the moving particle surfaces. ☐ In recent years, the lattice Boltzmann method (LBM) has emerged as an efficient and accurate numerical approach for computational fluid dynamics. Compared to the conventional approaches of directly solving the Navier-Stokes equations, LBM is simple to code, easy to parallelize, and flexible in treating boundary conditions. In particular, the no-slip boundary treatment based on bounce-back scheme and mesoscopic momentum exchange in LBM take full advantage of the gas kinetic description. However, the realization of these treatments in particle-laden turbulent flow simulations is still rare. So far, the majority of the particle-laden turbulent flow simulations relies on the smoothed-boundary treatments, such as the immersed boundary methods, which tends to induce artificial dissipation. In this dissertation, LBM with a sharp-interface treatment is developed to investigate turbulence modulation by finite-size solid particles. ☐ After a thorough validation, the method is applied to the simulations of a turbulent channel flow laden with both fixed and moving particles. The interactions between the dispersed particles and carrier turbulent flows, especially the modulation induced by the particles on the turbulence intensity and its parameter dependence are examined. The addition of particles is found to result in a more homogeneous distribution of turbulent kinetic energy (TKE) in the wall normal direction and a more isotropic TKE distribution among different spatial directions, comparing to the single-phase turbulent channel flow. To gain further insight, the budget equations of both the total TKE and component-wise TKE in the particle-laden turbulent flows are derived and analyzed using the simulation data. The budget analysis of the total TKE shows that the production rate of TKE from the mean flow is modified to become more uniform in the wall-normal direction by the presence of particles, which is responsible for the more homogeneous distribution of TKE. Specifically, in the buffer region where the TKE source is maximized in the single-phase flow, the TKE source due to the mean shear is reduced since both the mean flow velocity gradient and the Reynolds stress are reduced by the presence of particles. This reduction is found to be related to the particle inertia, where particles with larger inertia result in greater reduction of the TKE source. On the other hand, particles pump energy to turbulent fluctuations by doing work directly (moving particles) or inducing disturbances to the mean flow (fixed particles), converting more mechanical energy from the mean flow to the turbulent motion. The strength of this extra TKE source is related to the dynamics of the wake developed behind particles and therefore is particle-Reynolds-number dependent. The relative strength of the above two mechanisms determines whether the turbulence intensity of a turbulent channel flow is augmented or attenuated by the presence of particles. The budget analysis of component-wise TKE reveals that the more isotropic distribution of TKE among different spatial directions results from the enhanced inter-components transfer of TKE. This enhancement is found to originate from the spherical shape of the particles and particle rotation. ☐ In summary, the improved LBM simulation method based on the sharp-interface treatment provides a better alternative for particle-laden turbulent flow simulations than the commonly used smoothed-interface treatments. The physical results from this dissertation research advance our understanding of flow modulation induced by finite-size solid particles in turbulent flows, particularly in wall-bounded turbulent flows.
Download or read book Turbulence Modelling Approaches written by Konstantin Volkov and published by BoD – Books on Demand. This book was released on 2017-07-26 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate prediction of turbulent flows remains a challenging task despite considerable work in this area and the acceptance of CFD as a design tool. The quality of the CFD calculations of the flows in engineering applications strongly depends on the proper prediction of turbulence phenomena. Investigations of flow instability, heat transfer, skin friction, secondary flows, flow separation, and reattachment effects demand a reliable modelling and simulation of the turbulence, reliable methods, accurate programming, and robust working practices. The current scientific status of simulation of turbulent flows as well as some advances in computational techniques and practical applications of turbulence research is reviewed and considered in the book.
Download or read book Cleaner Combustion and Sustainable World written by Haiying Qi and published by Springer Science & Business Media. This book was released on 2012-11-19 with total page 1306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cleaner Combustion and Sustainable World is the proceedings of the 7th International Symposium on Coal Combustion which has a significant international influence. It concerns basic research on coal combustion and clean utilization, techniques and equipments of pulverized coal combustion, techniques and equipments of fluidized bed combustion, basic research and techniques of emission control, basic research and application techniques of carbon capture and storage (CCS), etc. Professor Haiying Qi and Bo Zhao both work at the Tsinghua University, China
Download or read book New Approaches in Modeling Multiphase Flows and Dispersion in Turbulence Fractal Methods and Synthetic Turbulence written by F.C.G.A. Nicolleau and published by Springer Science & Business Media. This book was released on 2011-10-29 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a collection of the main contributions from the first five workshops held by Ercoftac Special Interest Group on Synthetic Turbulence Models (SIG42. It is intended as an illustration of the sig’s activities and of the latest developments in the field. This volume investigates the use of Kinematic Simulation (KS) and other synthetic turbulence models for the particular application to environmental flows. This volume offers the best syntheses on the research status in KS, which is widely used in various domains, including Lagrangian aspects in turbulence mixing/stirring, particle dispersion/clustering, and last but not least, aeroacoustics. Flow realizations with complete spatial, and sometime spatio-temporal, dependency, are generated via superposition of random modes (mostly spatial, and sometime spatial and temporal, Fourier modes), with prescribed constraints such as: strict incompressibility (divergence-free velocity field at each point), high Reynolds energy spectrum. Recent improvements consisted in incorporating linear dynamics, for instance in rotating and/or stably-stratified flows, with possible easy generalization to MHD flows, and perhaps to plasmas. KS for channel flows have also been validated. However, the absence of "sweeping effects" in present conventional KS versions is identified as a major drawback in very different applications: inertial particle clustering as well as in aeroacoustics. Nevertheless, this issue was addressed in some reference papers, and merits to be revisited in the light of new studies in progress.
Download or read book Turbulent Flows written by Jean Piquet and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 767 pages. Available in PDF, EPUB and Kindle. Book excerpt: obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.
Download or read book Modeling Approaches and Computational Methods for Particle laden Turbulent Flows written by Shankar Subramaniam and published by Academic Press. This book was released on 2022-10-20 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling Approaches and Computational Methods for Particle-laden Turbulent Flows introduces the principal phenomena observed in applications where turbulence in particle-laden flow is encountered while also analyzing the main methods for analyzing numerically. The book takes a practical approach, providing advice on how to select and apply the correct model or tool by drawing on the latest research. Sections provide scales of particle-laden turbulence and the principal analytical frameworks and computational approaches used to simulate particles in turbulent flow. Each chapter opens with a section on fundamental concepts and theory before describing the applications of the modelling approach or numerical method. Featuring explanations of key concepts, definitions, and fundamental physics and equations, as well as recent research advances and detailed simulation methods, this book is the ideal starting point for students new to this subject, as well as an essential reference for experienced researchers. Provides a comprehensive introduction to the phenomena of particle laden turbulent flow Explains a wide range of numerical methods, including Eulerian-Eulerian, Eulerian-Lagrange, and volume-filtered computation Describes a wide range of innovative applications of these models
Download or read book Computation and Comparison of Efficient Turbulence Models for Aeronautics European Research Project ETMA written by Alain Dervieux and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains contributions to the BRITE-EURAM 3rd Framework Programme ETMA and extended articles of the TMA-Workshop. It focusses on turbulence modelling techniques suitable to use in typical flow configurations, with emphasis on compressibility effects and inherent unsteadiness. These methodologies are applied to the Navier-Stokes equations, involving various turbulence modelling levels from algebraic to RSM. Basic turbulent flows in aeronautics are considered; mixing layers, wall-flows (flat-plate, backward-facing step, ramp, bump), and more complex configurations (bump, aerofoil). A critical assessment of the turbulence modelling performances is offered, based on previous results and on the experimental data-base of this research programme. The ETMA results figure in the data-base constituted by all partners and organized by INRIA
Download or read book Turbulence Modulation in Particle Laden Flow with Mono Dispersed Droplets written by 呂偉福 and published by . This book was released on 2010 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
