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Velocity Wave Vector Probability Density Function Models For Inhomogeneous Turbulent Flows
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Book Synopsis Velocity/wave-vector Probability Density Function Models for Inhomogeneous Turbulent Flows by : Paul Richard Van Slooten
Download or read book Velocity/wave-vector Probability Density Function Models for Inhomogeneous Turbulent Flows written by Paul Richard Van Slooten and published by . This book was released on 1998 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constructs and implements turbulence models for probability density function (PDF) methods for the computation of turbulent reacting flows. Treats the processes of convection and reaction without further assumptions at this level of closure, while the effects of the fluctuation pressure gradient and the diffusion of the fluctuating velocity by molecular viscosity require modeling. Effects correspond to the pressure-rate-of-strain correlations, the pressure transport, and the dissipation tensor in the Reynolds stress equation. Investigates models for each of these variables.
Book Synopsis PDF Modeling of Turbulent Flows on Unstructured Grids by : József Bakosi
Download or read book PDF Modeling of Turbulent Flows on Unstructured Grids written by József Bakosi and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In probability density function (PDF) methods of turbulent flows, the joint PDF of several flow variables is computed by numerically integrating a system of stochastic differential equations for Lagrangian particles. Because the technique solves a transport equation for the PDF of the velocity and scalars, a mathematically exact treatment of advection, viscous effects and arbitrarily complex chemical reactions is possible; these processes are treated without closure assumptions. A set of algorithms is proposed to provide an efficient solution of the PDF transport equation modeling the joint PDF of turbulent velocity, frequency and concentration of a passive scalar in geometrically complex configurations. An unstructured Eulerian grid is employed to extract Eulerian statistics, to solve for quantities represented at fixed locations of the domain and to track particles. All three aspects regarding the grid make use of the finite element method. Compared to hybrid methods, the current methodology is stand-alone, therefore it is consistent both numerically and at the level of turbulence closure without the use of consistency conditions. Since both the turbulent velocity and scalar concentration fields are represented in a stochastic way, the method allows for a direct and close interaction between these fields, which is beneficial in computing accurate scalar statistics. Boundary conditions implemented along solid bodies are of the free-slip and no-slip type without the need for ghost elements. Boundary layers at no-slip boundaries are either fully resolved down to the viscous sublayer, explicitly modeling the high anisotropy and inhomogeneity of the low-Reynolds-number wall region without damping or wall-functions or specified via logarithmic wall-functions. As in moment closures and large eddy simulation, these wall-treatments provide the usual trade-off between resolution and computational cost as required by the given application. Particular attention is focused on modeling the dispersion of passive scalars in inhomogeneous turbulent flows. Two different micromixing models are investigated that incorporate the effect of small scale mixing on the transported scalar: the widely used interaction by exchange with the mean and the interaction by exchange with the conditional mean model. An adaptive algorithm to compute the velocity-conditioned scalar mean is proposed that homogenizes the statistical error over the sample space with no assumption on the shape of the underlying velocity PDF. The development also concentrates on a generally applicable micromixing timescale for complex flow domains. Several newly developed algorithms are described in detail that facilitate a stable numerical solution in arbitrarily complex flow geometries, including a stabilized mean-pressure projection scheme, the estimation of conditional and unconditional Eulerian statistics and their derivatives from stochastic particle fields employing finite element shapefunctions, particle tracking through unstructured grids, an efficient particle redistribution procedure and techniques related to efficient random number generation. The algorithm is validated and tested by computing three different turbulent flows: the fully developed turbulent channel flow, a street canyon (or cavity) flow and the turbulent wake behind a circular cylinder at a sub-critical Reynolds number. The solver has been parallelized and optimized for shared memory and multi-core architectures using the OpenMP standard. Relevant aspects of performance and parallelism on cache-based shared memory machines are discussed and presented in detail. The methodology shows great promise in the simulation of high-Reynolds-number incompressible inert or reactive turbulent flows in realistic configurations.
Book Synopsis Developments in the Probability Density Function Method for Turbulent Flows by : Daniel Connell Haworth
Download or read book Developments in the Probability Density Function Method for Turbulent Flows written by Daniel Connell Haworth and published by . This book was released on 1986 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Statistical Theory and Modeling for Turbulent Flows by : P. A. Durbin
Download or read book Statistical Theory and Modeling for Turbulent Flows written by P. A. Durbin and published by John Wiley & Sons. This book was released on 2011-06-28 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a comprehensive grounding in the subject of turbulence, Statistical Theory and Modeling for Turbulent Flows develops both the physical insight and the mathematical framework needed to understand turbulent flow. Its scope enables the reader to become a knowledgeable user of turbulence models; it develops analytical tools for developers of predictive tools. Thoroughly revised and updated, this second edition includes a new fourth section covering DNS (direct numerical simulation), LES (large eddy simulation), DES (detached eddy simulation) and numerical aspects of eddy resolving simulation. In addition to its role as a guide for students, Statistical Theory and Modeling for Turbulent Flows also is a valuable reference for practicing engineers and scientists in computational and experimental fluid dynamics, who would like to broaden their understanding of fundamental issues in turbulence and how they relate to turbulence model implementation. Provides an excellent foundation to the fundamental theoretical concepts in turbulence. Features new and heavily revised material, including an entire new section on eddy resolving simulation. Includes new material on modeling laminar to turbulent transition. Written for students and practitioners in aeronautical and mechanical engineering, applied mathematics and the physical sciences. Accompanied by a website housing solutions to the problems within the book.
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.
Book Synopsis Turbulence Models and Their Application by : Tuncer Cebeci
Download or read book Turbulence Models and Their Application written by Tuncer Cebeci and published by Springer Science & Business Media. This book was released on 2003-12-04 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: After a brief review of the more popular turbulence models, the author presents and discusses accurate and efficient numerical methods for solving the boundary-layer equations with turbulence models based on algebraic formulas (mixing length, eddy viscosity) or partial-differential transport equations. A computer program employing the Cebeci-Smith model and the k-e model for obtaining the solution of two-dimensional incompressible turbulent flows without separation is discussed in detail and is presented in the accompanying CD.
Book Synopsis Second-order Closure Models for Rotating Turbulent Flows by : Charles G. Speziale
Download or read book Second-order Closure Models for Rotating Turbulent Flows written by Charles G. Speziale and published by . This book was released on 1985 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling Particle-laden Turbulent Flows with the Conditional Quadrature Method of Moments by : Dennis Martin Dunn
Download or read book Modeling Particle-laden Turbulent Flows with the Conditional Quadrature Method of Moments written by Dennis Martin Dunn and published by . This book was released on 2015 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventional fluid dynamics models such as the Navier-Stokes equations are derived for prediction of fluid motion at or near equilibrium, classic examples being the motion of fluids for which inter-molecular collisions are dominant. Flows at equilibrium permit simplifications such as the introduction of viscosity and also lead to solutions that are single-valued. However, many other regimes of interest include "fluids"' far from equilibrium; for example, rarefied gases or particle-laden flows in which the dispersed phase can be comprised of granular solids, droplets, or bubbles. Particle motion in these flows is not typically dominated by collisions and may exhibit significant memory effects; therefore, is often poorly described using continuum, field-based (Eulerian) approaches. Non-equilibrium flows generally lack a straightforward counterpart to viscosity and their multi-valued solutions cannot be represented by most Eulerian methods. This strongly motivates different strategies to address current shortcomings and the novel approach adopted in this work is based on the Conditional Quadrature Method of Moments (CQMOM). In CQMOM, moment equations are derived from the Boltzmann equation using a quadrature approximation of the velocity probability density function (PDF). CQMOM circumvents the drawbacks of current methods and leads to multivariate and multidimensional solutions in an Eulerian frame of reference. In the present work, the discretized PDF is resolved using an adaptive two-point quadrature in three-dimensional velocity space. The method is applied to computation of a series of non-equilibrium flows, ranging from simple two-dimensional test cases to fully-turbulent three-dimensional wall-bounded particle-laden flows. The primary contribution of the present effort is on development, application, and assessment of CQMOM for predicting the key features of dilute particle-laden flows. Statistical descriptors such as mean concentration and mean velocity are in good agreement with previous results, for both collision-less and collisional flows at varying particle Stokes numbers. Turbulent statistics and measures of local accumulation agree less favorably with prior results and identify areas for improvement in the modeling strategy.
Book Synopsis Modeling of Scalar Probability Density Functions in Turbulent Flows by : Ashok Kumara Varma
Download or read book Modeling of Scalar Probability Density Functions in Turbulent Flows written by Ashok Kumara Varma and published by . This book was released on 1978 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent flows involving chemical reactions are a basic feature of many combustion and propulsion systems. The development of calculation procedures for turbulent reacting flows requires the understanding and modeling of the coupling between turbulence and combustion. Second-order closure modeling of turbulent flows provides a convenient framework for studying these interactions between turbulence and chemical reactions. Models for the scalar probability density function (pdf) have to be developed to achieve closure of turbulent transport equations for mixing and reacting flows. A delta function 'typical eddy' model has been developed for the joint pdf of the scalar variables. It has been demonstrated that delta functions are a necessary part of pdf's in order to attain the extremums of the statistical constraints on the moments. The statistical bounds on a number of moments of interest have been derived. It has been proven that a rational pdf composed of a set of delta functions alone can always be constructed at any point within the statistically valid moment space. The model provides a good representation of actual pdf's in two-species, variable-density mixing flows. The model has been directly compared to experimental pdf measurements and good agreement for higher-order moments has been demonstrated. It can be shown that the delta function pdf model is significantly simpler than other proposed pdf models and is more than adequate for the closure of the transport equations. (Author).
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Second Order Closure Model for Turbulent Reacting Flows by : Mohammad Farshchi
Download or read book Second Order Closure Model for Turbulent Reacting Flows written by Mohammad Farshchi and published by . This book was released on 1985 with total page 340 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 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Constructive Modeling of Structural Turbulence and Hydrodynamic Instabilities by : Oleg Mikhailovich Belotserkovskii
Download or read book Constructive Modeling of Structural Turbulence and Hydrodynamic Instabilities written by Oleg Mikhailovich Belotserkovskii and published by World Scientific. This book was released on 2009 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides an original approach in the research of structural analysis of free developed shear compressible turbulence at high Reynolds number on the base of direct numerical simulation (DNS) and instability evolution for ideal medium (integral conservation laws) with approximate mechanism of dissipation (FLUX dissipative monotone OC upwindOCO difference schemes) and does not use any explicit sub-grid approximation and semi-empirical models of turbulence. Convective mixing is considered as a principal part of conservation law.
Book Synopsis Developing New Generation of Models for Turbulent Flows by : Katepalli R. Sreenivasan
Download or read book Developing New Generation of Models for Turbulent Flows written by Katepalli R. Sreenivasan and published by . This book was released on 1997 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of the study was to generate, from a simple set of rules, a stochastic signal in space-time that would closely resemble the real turbulent data. This goal has been achieved and the work is reported in a journal article (Phys. Rev. E. 49, 5179, 1994) and Chapter 4.4 of the Ph. D thesis by A. Juneja (May 1995). The paper explains the principles and deals with one dimensional signals whereas the thesis chapter deals with three dimensional signals. These synthetic signals possess most of the statistical properties of real turbulence, and have been used as initial conditions in a direct numerical simulation of homogeneous turbulence. A comparable scheme was attempted for wall bounded flows, and the principal hypothesis relating to this attempt was successfully verified in a high-Reynolds-number turbulent pipe flow and a moderate-Reynolds-number turbulent boundary layer.
Book Synopsis Mathematical and Numerical Foundations of Turbulence Models and Applications by : Tomás Chacón Rebollo
Download or read book Mathematical and Numerical Foundations of Turbulence Models and Applications written by Tomás Chacón Rebollo and published by Springer. This book was released on 2014-06-17 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: With applications to climate, technology, and industry, the modeling and numerical simulation of turbulent flows are rich with history and modern relevance. The complexity of the problems that arise in the study of turbulence requires tools from various scientific disciplines, including mathematics, physics, engineering and computer science. Authored by two experts in the area with a long history of collaboration, this monograph provides a current, detailed look at several turbulence models from both the theoretical and numerical perspectives. The k-epsilon, large-eddy simulation and other models are rigorously derived and their performance is analyzed using benchmark simulations for real-world turbulent flows. Mathematical and Numerical Foundations of Turbulence Models and Applications is an ideal reference for students in applied mathematics and engineering, as well as researchers in mathematical and numerical fluid dynamics. It is also a valuable resource for advanced graduate students in fluid dynamics, engineers, physical oceanographers, meteorologists and climatologists.
Book Synopsis Prediction of Turbulent Flows by : Geoff Hewitt
Download or read book Prediction of Turbulent Flows written by Geoff Hewitt and published by Cambridge University Press. This book was released on 2005-06-08 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prediction of turbulent flows is of paramount importance in the development of complex engineering systems involving flow, heat and mass transfer, and chemical reactions. Arising from a programme held at the Isaac Newton Institute in Cambridge, this volume reviews the current situation regarding the prediction of such flows through the use of modern computational fluid dynamics techniques, and attempts to address the inherent problem of modelling turbulence. In particular, the current physical understanding of such flows is summarised and the resulting implications for simulation discussed. The volume continues by surveying current approximation methods whilst discussing their applicability to industrial problems. This major work concludes by providing a specific set of guidelines for selecting the most appropriate model for a given problem. Unique in its breadth and critical approach, this book will be of immense value to experienced practitioners and researchers, continuing the UK's strong tradition in fluid dynamics.
Book Synopsis Computation of Turbulent Flows by : W. C. Reynolds
Download or read book Computation of Turbulent Flows written by W. C. Reynolds and published by . This book was released on 1975 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
