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Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The extensive experimental study of dispersed two-phase turbulent flow in a vertical channel has been performed in Eaton's research group in the Mechanical Engineering Department at Stanford University. In Wang & Squires (1996), this study motivated the validation of LES approach with Lagrangian tracking of round particles governed by drag forces. While the computed velocity of the flow have been predicted relatively well, the computed particle velocity differed strongly from the measured one. Using Monte Carlo simulation of inter-particle collisions, the computation of Yamamoto et al. (2001) was specifically performed to model Eaton's experiment. The results of Yamamoto et al. (2001) improved the particle velocity distribution. At the same time, Vance & Squires (2002) mentioned that the stochastic simualtion of inter-particle collisions is too expensive, requiring significantly more CPU resources than one needs for the gas flow computation. Therefore, the need comes to account for the inter-particle collisions in a simpler and still effective way. To present such a model in the framework of LES/Lagrangian particle approach, and to compare the calculated results with Eaton's measurement and modeling of Yamamoto is the main objective of the present paper.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The extensive experimental study of dispersed two-phase turbulent flow in a vertical channel has been performed in Eaton's research group in the Mechanical Engineering Department at Stanford University. In Wang & Squires (1996), this study motivated the validation of LES approach with Lagrangian tracking of round particles governed by drag forces. While the computed velocity of the flow have been predicted relatively well, the computed particle velocity differed strongly from the measured one. Using Monte Carlo simulation of inter-particle collisions, the computation of Yamamoto et al. (2001) was specifically performed to model Eaton's experiment. The results of Yamamoto et al. (2001) improved the particle velocity distribution. At the same time, Vance & Squires (2002) mentioned that the stochastic simualtion of inter-particle collisions is too expensive, requiring significantly more CPU resources than one needs for the gas flow computation. Therefore, the need comes to account for the inter-particle collisions in a simpler and still effective way. To present such a model in the framework of LES/Lagrangian particle approach, and to compare the calculated results with Eaton's measurement and modeling of Yamamoto is the main objective of the present paper.
Author: Aleksei Y. Varaksin Publisher: Springer Science & Business Media ISBN: 3540680543 Category : Science Languages : en Pages : 204
Book Description
This book presents results of experimental and theoretical studies of "gas-solid particles" turbulent two-phase flows. It analyzes the characteristics of heterogeneous flows in channels (pipes), as well as those in the vicinity of the critical points of bodies subjected to flow and in the boundary layer developing on their surface. Coverage also treats in detail problems of physical simulation of turbulent gas flows which carry solid particles.
Author: Leonid I. Zaichik Publisher: John Wiley & Sons ISBN: 3527626263 Category : Science Languages : en Pages : 318
Book Description
The only work available to treat the theory of turbulent flow with suspended particles, this book also includes a section on simulation methods, comparing the model results obtained with the PDF method to those obtained with other techniques, such as DNS, LES and RANS. Written by experienced scientists with background in oil and gas processing, this book is applicable to a wide range of industries -- from the petrol industry and industrial chemistry to food and water processing.
Author: Jean-Pierre Minier Publisher: Springer ISBN: 9783319823850 Category : Technology & Engineering Languages : en Pages : 261
Book Description
The book presents an up-to-date review of turbulent two-phase flows with the dispersed phase, with an emphasis on the dynamics in the near-wall region. New insights to the flow physics are provided by direct numerical simuation and by fine experimental techniques. Also included are models of particle dynamics in wall-bounded turbulent flows, and a description of particle surface interactions including muti-layer deposition and re-suspension.
Author: Peter Dearborn Huck Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Turbulence is well known for its ability to efficiently disperse matter, whether it be atmospheric pollutants or gasoline in combustion motors. Two considerations are fundamental when considering such situations. First, the underlying flow may have a strong influence of the behavior of the dispersed particles. Second, the local concentration of particles may enhance or impede the transport properties of turbulence. This dissertation addresses these points separately through the experimental study of two different turbulent flows. The first experimental device used is the so-called von K\'arm\'an flow which consists of an enclosed vessel filled with water that is forced by two counter rotating disks creating a strongly inhomogeneous and anisotropic turbulence. Two high-speed cameras permitted the creation a trajectory data base particles that were both isodense and heavier than water but were smaller than the smallest turbulent scales. The trajectories of this data base permitted a study of the turbulent kinetic energy budget which was shown to directly related to the transport properties of the turbulent flow. The heavy particles illustrate the role of flow anisotropy in the dispersive dynamics of particles dominated by effects related to their inertia. The second flow studied was a wind tunnel seeded with micrometer sized water droplets which was used to study the effects of local concentration of the settling velocities of these particles. A model based on theoretical multi-phase methods was developed in order to take into account the role of collective effects on sedimentation in a turbulent flow. The theoretical results emphasize the role of coupling between the underlying flow and the dispersed phase.
Author: Lixing Zhou Publisher: Butterworth-Heinemann ISBN: 0128134666 Category : Technology & Engineering Languages : en Pages : 343
Book Description
Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows gives a systematic account of the fundamentals of multiphase flows, turbulent flows and combustion theory. It presents the latest advances of models and theories in the field of dispersed multiphase turbulent reacting flow, covering basic equations of multiphase turbulent reacting flows, modeling of turbulent flows, modeling of multiphase turbulent flows, modeling of turbulent combusting flows, and numerical methods for simulation of multiphase turbulent reacting flows, etc. The book is ideal for graduated students, researchers and engineers in many disciplines in power and mechanical engineering. - Provides a combination of multiphase fluid dynamics, turbulence theory and combustion theory - Covers physical phenomena, numerical modeling theory and methods, and their applications - Presents applications in a wide range of engineering facilities, such as utility and industrial furnaces, gas-turbine and rocket engines, internal combustion engines, chemical reactors, and cyclone separators, etc.
Book Description
This book contributes to the fundamental understanding of the physical mechanisms that take place in pseudo turbulent particulate flows. In the present work we have considered the sedimentation of large numbers of spherical rigid particles in an initially quiescent flow field. We have performed direct numerical simulations employing an immersed boundary method for the representation of the fluid-solid interface. The results evidence that depending on the particle settling regime (i.e. Galileo number and particle-to-fluid density ratio) the particles may exhibit strong inhomogeneous spatial distribution. It is found that the particles are preferentially located in regions with downward fluid motion. The particles inside clusters experience larger settling velocities than the average. The flow in all flow cases is observed to exhibit characteristic features of pseudo-turbulence. The particle-induced flow field is further found to be highly anisotropic with dominant vertical components. The results indicate that, in the present flow configurations, the collective and mobility effects play significant role for the particle and fluid motion.
Author: Alessio Innocenti Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The present thesis deals with the study and modeling of turbulent two-phase flows and in particular with the mechanisms of turbulence production by a dispersed phase. The objective is to propose reduced models for practical applications and to understand the underlying physics thanks to direct numerical simulations (DNS). The first part covers gas-solid particles flows with a Eulerian (for the fluid) - Lagrangian (for particles) approach. We have proposed a stochastic model for tracking particles in a turbulent Large-Eddy velocity field (LES) in dilute flows, with results very close to DNS. When the mass fraction of the particle phase is significant (dense flows) the effect of the particles on the fluid is accounted for with a two-way coupled stochastic model for the particles, which considers also particle collisions, in a Reynolds-Average equations context (RANS). This model has been tested and validated in different homogeneous and non-homogeneous cases, and in a Cluster Induced Turbulence configuration. The second part focuses on the study of the upward motion of bubbles in a liquid. The numerical code (Basilisk) that we have used has been validated with periodic configurations against different literature studies. We have then investigated several technical problems, like the criteria for the local refinement of the adaptive mesh and the density ratio of the two fluids. Finally, we have studied a bubble column configuration in two and three dimensions, analyzing the spectra and PDFs to describe the fluctuations induced by the bubbles in the liquid.
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Author: Aleksei Y. Varaksin
Author: Leonid I. Zaichik
Author: Jean-Pierre Minier
Author: Peter Dearborn Huck
Author: Per-Arne Sundsbø
Author: Lixing Zhou
Author: Maurizio Picciotto
Author: Doychev, Todor
Author: Alessio Innocenti