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Numerical Simulation Of Solid Particle Transport In Atmospheric Boundary Layer Over Obstacles
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Book Synopsis Numerical Simulation of Solid Particle Transport in Atmospheric Boundary-layer Over Obstacles by : Gang Huang
Download or read book Numerical Simulation of Solid Particle Transport in Atmospheric Boundary-layer Over Obstacles written by Gang Huang and published by . This book was released on 2015 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transport of solid particles inside a laboratory-scale turbulent boundary-layer is studied by numerical simulations, to obtain a better understanding of the mechanisms associated with wind erosion of soil. The presence of one or several Gaussian hills allows a study of the topographic effects on the transport, deposition and re-emission of solid particles. The carrier fluid motion is resolved in a Large Eddy Simulation (LES). Wall models are implemented to better account for the effects of turbulent flow near the terrain. Particle trajectories are calculated using a Lagrangian tracking. Take-off and rebound models are developed in order to take into account particle emissions and impacts at the wall. In the first part, the flow over transversal Gaussian hills is simulated and validated by comparison with different experiments. According to Oke [1988], the flow inside an urban canopy can be schematically characterised into different flow regimes depending on the relative localisation of the obstacles at the ground. This concept is applied to the case of sand dunes, assimilated to 2D hills in this study. The focus is on the recirculation zone (RZ) on the lee side, which has the characteristic of increasing the residence time and the interaction fluid/particle in general, particle trapping and deposition in particular. The variations of RZ with different hill geometries and Reynolds numbers are examined. A study on the roughness sublayer is conducted in order to determine the roughness effects due to the layer of solid particles on the wall. The second part of the work is devoted to the simulation of solid particle transport over the Gaussian hills. The objective is to improve the modelling of particle take-off, rebound and the two-way coupling between the fluid and the particle. A first work of validation is conducted by using the complete model of solid particle transport developed in this thesis. In particular, the evolution of particle emission flux predicted by the take-off model is in accordance with classical saltation models and experiments from the literature. Over the Gaussian hills, analysis of particle transport is conducted using concentration and mean velocity fields. Two mappings are realised. The first indicates the intensity of the local and instantaneous flow structures that arguably regulate the re-entrainment of particles trapped inside the RZ. The second shows the accumulation of particles on the wall. These results highlight zones prone to wind erosion and particle deposition around the hills. Last but not least, the fluxes of particle trapping and deposition inside the RZ are quantified and compared to the incoming flux from upstream. These fluxes, albeit relatively weak in comparison to the incoming one, contribute potentially to dune migrations and desertification.
Book Synopsis Modeling of Gas-to-Particle Mass Transfer in Turbulent Flows by : Sean C. Garrick
Download or read book Modeling of Gas-to-Particle Mass Transfer in Turbulent Flows written by Sean C. Garrick and published by Springer. This book was released on 2017-06-29 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief focuses on the dispersion of high-porosity particles, their entrainment into the vapor-laden stream, and the condensation of vapor onto the particles. The authors begin with a simple/static problem, focusing on transport within the particle. They go on to consider the high-resolution simulation of particles in a turbulent flow and the time-dependent evolution of the fluid-particle fields. Finally, they examine the more computationally-affordable large-eddy simulation of gas-to-particle mass-transfer. The book ends with a summary and challenges as well as directions for the area.
Book Synopsis Direct Numerical Simulation of Momentum and Scalar Transport in Clear and Particle Laden Turbulent Boundary Layers by : Changfeng Li
Download or read book Direct Numerical Simulation of Momentum and Scalar Transport in Clear and Particle Laden Turbulent Boundary Layers written by Changfeng Li and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulation of Particle-Wave Interaction on Boundary Layers by :
Download or read book Numerical Simulation of Particle-Wave Interaction on Boundary Layers written by and published by . This book was released on 1994 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program involves a computational study of the effects of disturbances generated from a moving particle on boundary layer transition. The practical importance of this problem stems from the fact that as an underwater vehicle moves through a particulate environment, particles enter the boundary layer and produce local disturbances. These disturbances may act as a bypass mechanism to transition and turbulence by interacting with boundary layer instabilities. The objective of this research is to study the basic mechanisms of the particle interaction and its effect on transition in the boundary layer. For this purpose, a direct numerical simulation is undertaken and the spherical particle is represented by a forcing function in the Navier Stokes equations. Results reveal good agreement with experimental studies. The report is presented in two parts. The first part concerns a general overview of the work accomplished and the second part summarizes our recent efforts on the modeling of steady/unsteady flow over a cylinder.
Book Synopsis Numerical Simulation of Shock/Turbulent Boundary Layer Interaction by : National Aeronautics and Space Adm Nasa
Download or read book Numerical Simulation of Shock/Turbulent Boundary Layer Interaction written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most flows of aerodynamic interest are compressible and turbulent. However, our present knowledge on the structures and mechanisms of turbulence is mostly based on incompressible flows. In the present work, compressibility effects in turbulent, high-speed, boundary layer flows are systematically investigated using the Direct Numerical Simulation (DNS) approach. Three-dimensional, time-dependent, fully nonlinear, compressible Navier-Stokes equations were numerically integrated by high-order finite-difference methods; no modeling for turbulence is used during the solution because the available resolution is sufficient to capture the relevant scales. The boundary layer problem deals with fully-turbulent compressible flows over flat geometries. Apart from its practical relevance to technological flows, turbulent compressible boundary layer flow is the simplest experimentally realizable turbulent compressible flow. Still, measuring difficulties prohibit a detailed experimental description of the flow, especially in the near-wall region. DNS studies provide a viable means to probe the physics of compressible turbulence in this region. The focus of this work is to explore the paths of energy transfer through which compressible turbulence is sustained. The structural similarities and differences between the incompressible and compressible turbulence are also investigated. The energy flow patterns or energy cascades are found to be directly related to the evolution of vortical structures which are generated in the near-wall region. Near-wall structures, and mechanisms which are not readily accessible through physical experiments are analyzed and their critical role on the evolution and the behavior of the flow is documented extensively. Biringen, Sedat and Hatay, Ferhat F. Unspecified Center NAG1-1472...
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722425272 Total Pages :28 pages Book Rating :4.4/5 (252 download)
Book Synopsis Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer by : National Aeronautics and Space Administration (NASA)
Download or read book Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: In support of the wake vortex effect of the Terminal Area Productivity program, we have put forward four tasks to be accomplished in our proposal. The first task is validation of two-dimensional wake vortex-turbulence interaction. The second task is investigation of three-dimensional interaction between wake vortices and atmospheric boundary layer (ABL) turbulence. The third task is ABL studies. The, fourth task is addition of a Klemp-Durran condition at the top boundary for TASS model. The accomplishment of these tasks will increase our understanding of the dynamics of wake vortex and improve forecasting systems responsible for air safety and efficiency. The first two tasks include following three parts: (a) Determine significant length scale for vortex decay and transport, especially the length scales associated with the onset of Crow instability (Crow, 1970); (b) Study the effects of atmospheric turbulence on the decay of the wake vortices; and (c) Determine the relationships between decay rate, transport properties and atmospheric parameters based on large eddy simulation (LES) results and the observational data. These parameters may include turbulence kinetic energy, dissipation rate, wind shear and atmospheric stratification. The ABL studies cover LES modeling of turbulence structure within planetary boundary layer under transition and stable stratification conditions. Evidences have shown that the turbulence in the stable boundary layer can be highly intermittent and the length scales of eddies are very small compared to those in convective case. We proposed to develop a nesting grid mesh scheme and a modified Klemp-Durran conditions (Klemp and Wilhelmson, 1978) at the top boundary for TASS model to simulate planetary boundary layer under stable stratification conditions. During the past year, our group has made great efforts to carry out the above mentioned four tasks simultaneously. The work accomplished in the last year will be described in the next sectio...
Book Synopsis Dispersion and Deposition of Heavy Particles in Turbulent Flows by : Chunyu Jin
Download or read book Dispersion and Deposition of Heavy Particles in Turbulent Flows written by Chunyu Jin and published by . This book was released on 2012 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Investigation of Particle Deposition in a Turbulent Boundary Layer with Forced Turbulence in the External Flow by : Manoj Joishi
Download or read book Numerical Investigation of Particle Deposition in a Turbulent Boundary Layer with Forced Turbulence in the External Flow written by Manoj Joishi and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deposition of particles on a wall plays a significant role in fluid-solid processes such as inclusions recovery from liquid steel in ladle furnace, that controls inclusion cleanliness upstream from solidification. The aim of this work is to study the turbulent deposition and capture of particles on a wall, in a situation where turbulence in the boundary layer originates both from wall shear and from agitation in the external flow. In a ladle furnace, such an agitation would result from bubble injection. A framework for simulations at mesoscopic scale in which particles are represented as points but the turbulence is fully resolved has been developped using an in-house solver, where a Lattice Boltzmann Method (LBM) solves flow dynamics and linear isotropic forcing generates artificial turbulence. Lagrangian Particle Tracking (LPT) is used to achieve one way coupling between particle motions and turbulent flow. These numerical methods were applied to Direct Numerical simulation (DNS) of a fully developed turbulent boundary layer in which particles smaller than the Kolmogorov length scale are introduced. The deposition mechanisms in aerosol conditions have been analyzed and quantified into a statistical law for deposition velocity in terms of Stokes number, and validated against data from the literature. Such simulations have provided a better understanding of deposition and capture mechanisms, depending on the turbulent flow in a wall boundary layer and on particle physical properties. Also, preliminary simulations in hydrosol conditions that match actual ladle operation have shown that the framework developed in this work can be applied to investigate inclusion behavior in secondary steel-making although statistical analysis in this work focused on aerosols.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1987 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulence and Self-Organization by : Mikhail Ya Marov
Download or read book Turbulence and Self-Organization written by Mikhail Ya Marov and published by Springer Science & Business Media. This book was released on 2013-01-16 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book deals with the development of continual models of turbulent natural media. Such models serve as a ground for the statement and numerical evaluation of the key problems of the structure and evolution of the numerous astrophysical and geophysical objects. The processes of ordering (self-organization) in an originally chaotic turbulent medium are addressed and treated in detail with the use of irreversible thermodynamics and stochastic dynamics approaches which underlie the respective models. Different examples of ordering set up in the natural environment and outer space are brought and thoroughly discussed, the main focus being given to the protoplanetary discs formation and evolution.
Book Synopsis Validation of Three-dimensional Incompressible Spatial Direct Numerical Simulation Code: A Comparison with Linear Stability and Parabolic Stability Equation Theories for Boundary-layer Transition on a Flat Plate by : Ronald D. Joslin
Download or read book Validation of Three-dimensional Incompressible Spatial Direct Numerical Simulation Code: A Comparison with Linear Stability and Parabolic Stability Equation Theories for Boundary-layer Transition on a Flat Plate written by Ronald D. Joslin and published by . This book was released on 1992 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1983 with total page 1468 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hybrid Particle Laden Flow Modelling by : David Schellander
Download or read book Hybrid Particle Laden Flow Modelling written by David Schellander and published by GRIN Verlag. This book was released on 2013-09-20 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Doctoral Thesis / Dissertation from the year 2013 in the subject Engineering - Mechanical Engineering, grade: 1, University of Linz (Department on Particulate Flow Modelling), language: English, abstract: The numerical hybrid model EUgran+, which is an Eulerian-Eulerian granular phase model extended with models from the Eulerian-Lagrangian model for dense rapid particulate flows, is modified to account for poly-dispersed particle diameter distributions. These modifications include the implementation of I) a new poly-dispersed drag law and of II) new particle boundary conditions distinguishing between sliding and non-sliding particle-wall collisions and III) a new implementation of the population balance equation in the agglomeration model using the Eulerian-Lagrangian approach, referred to as Bus-stop model. Further, the applicability of the EUgran+ model is extended to cover dilute to dense poly-disperse particulate flows. Furthermore, this provides an improvement in the numerical simulation of dust separation and the formation of particle strands in industrial scale cyclones. In this PHD thesis, the EUgran+Poly model is validated at 3 specific cases with different mass loadings: I) poly-dispersed particle conveying in a square pipe with a 90 degree bend at low mass loading (L = 0:00206); II) a particle conveying case in a rectangular pipe with a double-loop at high mass loading (L = 1:5); III) in a vertical pipe the implementation of the agglomeration model is validated. To show the applicability of the presented models a simulation of an industrial cyclone in experimental scale is presented. The validation and application shows that considering a poly-disperse Eulerian-Eulerian granular phase improves the accordance of the simulation results with measurements significantly. Finally, the hybrid model is a good compromise for a computational efficient simulation of particulate transport and separation with different mass loading regimes.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1048 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Lattice Boltzmann Method by : Timm Krüger
Download or read book The Lattice Boltzmann Method written by Timm Krüger and published by Springer. This book was released on 2016-11-07 with total page 705 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an introduction to the theory, practice, and implementation of the Lattice Boltzmann (LB) method, a powerful computational fluid dynamics method that is steadily gaining attention due to its simplicity, scalability, extensibility, and simple handling of complex geometries. The book contains chapters on the method's background, fundamental theory, advanced extensions, and implementation. To aid beginners, the most essential paragraphs in each chapter are highlighted, and the introductory chapters on various LB topics are front-loaded with special "in a nutshell" sections that condense the chapter's most important practical results. Together, these sections can be used to quickly get up and running with the method. Exercises are integrated throughout the text, and frequently asked questions about the method are dealt with in a special section at the beginning. In the book itself and through its web page, readers can find example codes showing how the LB method can be implemented efficiently on a variety of hardware platforms, including multi-core processors, clusters, and graphics processing units. Students and scientists learning and using the LB method will appreciate the wealth of clearly presented and structured information in this volume.
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:
