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 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:

Download or read book IUTAM Symposium on Computational Approaches to Multiphase Flow written by S. Balachandar and published by Springer Science & Business Media. This book was released on 2007-01-28 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a broad overview of the full spectrum of state-of-the-art computational activities in multiphase flow as presented by top practitioners in the field. It starts with well-established approaches and builds up to newer methods. These methods are illustrated with applications to a broad spectrum of problems involving particle dispersion and deposition, turbulence modulation, environmental flows, fluidized beds, bubbly flows, and many others.

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 MODULATION UNDER LARGE PARTICLE LOADING written by Aidan Stephen Cronin and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle-laden turbulence is important to a diverse range of topics: from aerosol transport in the atmosphere to flocculation techniques treating our drinking water. Often the particles in flows of interest are large and non-spherical, making them difficult to study, and so simplified cases are considered to quantify turbulent behaviors. Experimental laboratory research has provided insight into the quantifiable behavior of these simplified particle-laden flows, notably in cases of homogeneous and isotropic (H.I) turbulence. For this research, we designed and constructed a novel laboratory turbulence tank for the study of particle-laden flows that could create a region of H.I turbulence at its center. To do so, we incorporated random, symmetric forcing on a completely new geometry (a modified icosahedron) intending to maintain the properties of H.I. turbulence while increasing the size of the region of the tank in which it is contained. This facility will provide a unique testbed for studies of particle-laden turbulence.

Download or read book Turbulence Generation in Homogeneous Dilute Particle laden Flows written by Jeng-Horng Chen and published by . This book was released on 1999 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Direct and Large Eddy Simulation X written by Dimokratis G.E. Grigoriadis and published by Springer. This book was released on 2017-10-06 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses nearly all aspects of the state of the art in LES & DNS of turbulent flows, ranging from flows in biological systems and the environment to external aerodynamics, domestic and centralized energy production, combustion, propulsion as well as applications of industrial interest. Following the advances in increased computational power and efficiency, several contributions are devoted to LES & DNS of challenging applications, mainly in the area of turbomachinery, including flame modeling, combustion processes and aeroacoustics. The book includes work presented at the tenth Workshop on 'Direct and Large-Eddy Simulation' (DLES-10), which was hosted in Cyprus by the University of Cyprus, from May 27 to 29, 2015. The goal of the workshop was to establish a state of the art in DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows. The book is of interest to scientists and engineers, both in the early stages of their career and at a more senior level.

Download or read book Experimental Investigation on the Turbulence of Particle laden Liquid Flows in a Vertical Pipe Loop written by Rouholluh Shokri and published by . This book was released on 2016 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: The turbulent motion of particles and their interactions with the turbulence of the carrier phase make a complex system. Hence understanding the physics and consequently developing a well-stablished model becomes very difficult. With insufficient computational power to numerically resolve all the scales of these kinds of flows using Direct Numerical Simulation (DNS), experimental investigations still remain the sole source of information for these systems, especially at high Reynolds numbers. Lack of comprehensive experimental data for solid-liquid flows as well as limitation of the existing experimental data to low Reynolds numbers are the motivations for this investigation. The main goal of this research is to experimentally investigate solid-liquid turbulent flows in a vertical pipe and provide some insight into these flows, especially for an extended range of Reynolds numbers. To fulfil the abovementioned goal, a 50.6 mm vertical pipe loop was constructed and dilute mixtures of water and glass beads were used. The glass bead diameters were 0.5, 1 and 2 mm and the volumetric concentration ranged from 0.05 to 1.6% depending on the particle size. The experiments were performed at three Reynolds numbers: 52 000, 100 000, and 320 000 which are referred to here as low, medium and high Re. A combined technique of Particle Image/Tracking velocimetry (PIV/PTV) was employed to perform the measurements. The measured and reported flow parameters are: mean axial velocity profiles of the solid and liquid phases, particle distribution over the cross section of the pipe (concentration profile), particle-particle interaction index, axial and radial fluctuating velocity profiles of both phases, and shear Reynolds stress and its correlation for both phases. The relatively wide range of different parameters tested here provided interesting and novel experimental results. The results showed that the turbulent motions of the fluid and particles and their interactions varied drastically as Re increased. Moreover, the behavior of the particles and their impact on the fluid can be very different in the axial and radial directions. The results proved that the well-known criteria for axial turbulence modulation of the carrier phase could not perform well at high Reynolds numbers and their performance was much poorer for the radial direction modulation. The new data sets provided by the present study offer valuable insight into the processes or phenomena heavily influenced by turbulence, such as pipe wear rate, oil sand lump ablation, and pressure loss/energy consumption. In addition, these data sets can be utilised to evaluate and improve the existing correlations and models for particulate turbulent flows. In addition, a quantitative analysis of the particle and carrier phase turbulence modulation was conducted. Particle turbulence intensities in present study were combined with other experimental data from the literature to propose a novel empirical correlation was proposed for axial particle turbulence in solid-liquid flows. Moreover, a novel empirical criterion/correlation was proposed to classify the carrier phase turbulence attenuation/augmentation phenomenon for both gas-solid and liquid-solid flows by employing a wide range of data from the present study and from the literature. Two major improvements of the proposed criterion/correlation are the prediction of the onset and the magnitude of the carrier phase turbulence augmentation. These new empirical correlations will assist the researchers in this field to effectively design and coordinate their experimental or numerical efforts.

Download or read book Multiphase Flow Handbook Second Edition written by Efstathios Michaelides and published by CRC Press. This book was released on 2016-10-26 with total page 1559 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiphase Flow Handbook, Second Edition is a thoroughly updated and reorganized revision of the late Clayton Crowe’s work, and provides a detailed look at the basic concepts and the wide range of applications in this important area of thermal/fluids engineering. Revised by the new editors, Efstathios E. (Stathis) Michaelides and John D. Schwarzkopf, the new Second Edition begins with two chapters covering fundamental concepts and methods that pertain to all the types and applications of multiphase flow. The remaining chapters cover the applications and engineering systems that are relevant to all the types of multiphase flow and heat transfer. The twenty-one chapters and several sections of the book include the basic science as well as the contemporary engineering and technological applications of multiphase flow in a comprehensive way that is easy to follow and be understood. The editors created a common set of nomenclature that is used throughout the book, allowing readers to easily compare fundamental theory with currently developing concepts and applications. With contributed chapters from sixty-two leading experts around the world, the Multiphase Flow Handbook, Second Edition is an essential reference for all researchers, academics and engineers working with complex thermal and fluid systems.

Download or read book Turbulence Modulation and Dense Spray Structure written by R. N. Parthasarathy and published by . This book was released on 1988 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical and experimental study of phenomena related to dense sprays is described. Two aspects of dense sprays are being considered: effects of turbulence modulation, which is the direct effect of particle (drop) motion on the turbulence properties of multiphase flows; and the structure and mixing properties of the dense-spray region of pressure atomized sprays. Turbulence modulation is being studied by considering spherical monodisperse glass particles falling in a stagnant water bath, where effects of turbulence modulation are responsible for the entire turbulence field. Measurements involve phase velocities and temporal and spatial correlations and spectra of the continuous phase velocities using a two-point phase-discriminating laser Doppler anemometer. Flow properties are being analyzed using stochastic methods: assuming linear superposition of randomly arriving particle wakes (Poisson statistics) for liquid phase properties; and random-walk calculations based on statistical time-series methods for particle properties. Multiphase flow, Sprays, Particle-laden flow. (jes).

Download or read book Numerical Simulations of Two Way Coupling Effects in a Particle Laden Turbulent Pipe Flow And Evaluation of the Equilibrium Eulerian Approach for the Evolution of Particle Concentration in Isotropic Turbulence written by Sarma Laxminarasimha Rani and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A New Dynamic SGS Model for Large Eddy Simulation of Particle Laden Turbulent Flows written by Kangbin Lei and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper presents a new dynamic SGS model of two-way coupling for large eddy simulation of particle-laden turbulent flow. The advantage of this new model is that coupling of fluid-particles SGS components was taken into account and at the same time the coefficient of proposed SOS model can be optimized by Germano's (1991) dynamic procedure. To investigate the capability of this model, numerical simulations of particle-laden turbulent flow at Re=644 in a vertical channel were performed using this new dynamic SGS model. By comparing the calculation results with that using single-phase SGS models which didn't consider coupling of SGS components the role of particles SGS components played in the turbulence modulation of fluid flow was clarified for particle-laden channel turbulent flows. In addition, the subgrid-scale stresses obtained using the proposed model vanish at wall boundary, and have the correct asymptotic behavior in the near-wall region of the turbulent boundary.

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 Turbulence Modulation of Carrier phase in Fluid particle Flows written by Pengfei Wang and published by . This book was released on 2000 with total page 84 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 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 EFFECT OF PARTICLE CONCENTRATION AND REYNOLDS NUMBER ON HEAT TRANSFER IN PARTICLE LADEN FLOWS written by Sarah Masters and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is to understand heat transfer in particle-laden flows. Particle-laden flows are prevalent in multiple industries, including chemical, pharmaceutical, plastics, food, and agriculture. In many applications, it is necessary to heat or cool the particle-laden flow to achieve desired process conditions. It is therefore important to understand the heat transfer characteristics of particle-laden flows under varying process conditions. This research seeks to experimentally investigate how the concentration of particles in turbulent, particle-laden flow effect the heat transfer properties of the flow. An experimental setup to observe the heat transfer properties of particle-laden flows was designed and built in house. A MARK XV-HP powder feeder system was used to entrain copper particles (-325 mesh) into a flow of nitrogen gas. The particle-laden flow then traveled through a horizontal pipe with a constant heat flux applied to the wall. Surface and fluid temperatures along the test section were measured and used to calculate the heat transfer coefficient and Nusselt number of the flow. A range of Reynolds numbers from 30,000 to 65,000 as well as a range of solids loadings from 0.0 to 1.0 were tested. For solids loadings of 0.5, the Nusselt number increased at lower Reynolds numbers and then decreased at higher Reynolds numbers. For solids loadings of 1.0, the Nusselt number was lower at low Reynolds numbers and then increased at higher Reynolds numbers. A transition in Nusselt number occurred for both solids loadings, but they occurred at different Reynolds numbers. The Nusselt number for particle-laden flows did show a variance from the Nusselt number for gas only flows. The direction and quantity of this difference was dependent on solids loading and Reynolds number. These trends are proposed to be a result of different turbulence modulation effects, which are discussed herein.