Analysis and Modeling of Buoyance Generated Turbulence Using Numerical Data PDF Download
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Author: Sharath S. Girimaji
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
Author: Sharath S. Girimaji
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
Author: Sharath S. Girimaji
Publisher:
ISBN:
Category : Momentum transfer
Languages : en
Pages : 50
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 40
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Book Description
Rayleigh-Bernard convection offers a unique flow situation in which buoyancy-generated turbulence can be studied in isolation, free of the complicating influence of shear production of turbulence. The objective of this paper is to examine and model important aspects of buoyancy-generated turbulence using direct numerical simulation (DNS) data of Rayleigh-Bernard convection. In particular, we examine the pressure-strain and pressure temperature-gradient correlations, turbulent transport of Reynolds stress, and assumptions pertaining to algebraic modeling of thermal flux and Reynolds stress.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
Because of the importance of turbulence mixing in many applications, a number of turbulence mixing models have been proposed for variable- density flows. These engineering models (one- point statistical models) typically include the transport of the turbulent kinetic energy and the turbulent energy dissipation rate (i.e., k - [epsilon] models). The model presented by Besnard, Harlow, Rauenzahn and Zemach (1992) (herein referred to as BHRZ) is a one-point model intended to describe variable-density turbulent flows. Transport equations for the Reynolds stress tensor, R{sub ij}, and the turbulent energy dissipation rate, the density-velocity correlation, a{sub i}, and the density-specific volume correlation, b are derived. This model employs- techniques and concepts from incompressible, constant- density turbulence modeling and incorporates ideas from two-phase flow models. Clark and Spitz (1994) present a two-point model for variable-density turbulence. Their derivation is based on transport equations that, are based 0481 on two-point- generalizations of R{sub ij}, a{sub ij}, and b. These equations are Fourier transformed with respect to the separation distance between the two points. Transport equations are derived for R{sub ij}, a{sub i}, b. As in the one-point model, this model contains many ad-hoc assumptions and unknown model coefficients that must be determined by comparison with experimental and numerical data. However, the two-point formalism requires fewer equilibrium assumptions then does a single-point model. Our primary concern in this paper lies in the nonlinear processes of turbulence and the influence of large density variations (not within the Boussinesq limit) on these processes. To. isolate the effects of variable-density on the turbulence we restrict our flow to be incompressible, statistically homogeneous buoyancy-generated. turbulence. To our knowledge there have not been any simulations reported for this problem.
Author: Karthik Duraisamy
Publisher: Academic Press
ISBN: 9780323950435
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
Data-driven Analysis and Modeling of Turbulent Flows explains methods for the analysis of large fields of data, and uncovering models and model improvements from numerical or experimental data on turbulence. Turbulence simulations generate large data sets, and the extraction of useful information from these data fields is an important and challenging task. Statistical learning and machine learning have provided many ways of helping, and this book explains how to use such methods for extracting, treating, and optimizing data to improve predictive turbulence models. These include methods such as POD, SPOD and DMD, for the extraction of modes peculiar to the data, as well as several reduced order models. This resource is essential reading for those developing turbulence models, performing turbulence simulations or interpreting turbulence simulation results.
Author: Tomás Chacón Rebollo
Publisher: Springer
ISBN: 1493904558
Category : Mathematics
Languages : en
Pages : 530
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Book Description
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.
Author: Paul Durbin
Publisher: Elsevier
ISBN: 0128208902
Category : Technology & Engineering
Languages : en
Pages : 554
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Book Description
Advanced Approaches in Turbulence: Theory, Modeling, Simulation and Data Analysis for Turbulent Flows focuses on the updated theory, simulation and data analysis of turbulence dealing mainly with turbulence modeling instead of the physics of turbulence. Beginning with the basics of turbulence, the book discusses closure modeling, direct simulation, large eddy simulation and hybrid simulation. The book also covers the entire spectrum of turbulence models for both single-phase and multi-phase flows, as well as turbulence in compressible flow. Turbulence modeling is very extensive and continuously updated with new achievements and improvements of the models. Modern advances in computer speed offer the potential for elaborate numerical analysis of turbulent fluid flow while advances in instrumentation are creating large amounts of data. This book covers these topics in great detail. - Covers the fundamentals of turbulence updated with recent developments - Focuses on hybrid methods such as DES and wall-modeled LES - Gives an updated treatment of numerical simulation and data analysis
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
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Book Description
Author: Prakash Mohan (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Turbulence is a complex fluid phenomenon that is present in high Reynolds number flows. It has a profound effect on the flows in which it occurs, and it is therefore important to understand and model its effects. It occurs in multiple domains from flows inside our bodies to ocean currents and atmospheric winds. The difficulty in modeling and simulating turbulence arises from the fact that it is comprised of a wide range of scales that interact with each other non-linearly. The field of turbulence still has many open problems — from fundamental questions about the underlying physics to enabling tractable engineering models. The Navier-Stokes equations are a reliable representation of turbulent flows and solving them with sufficient accuracy gives us the detailed turbulent flow field. These are called Direct Numerical Simulations (DNS) and are an invaluable tool to study the turbulence phenomenon. In this work, we first consider how DNS of forced isotropic turbulence can be used to study time predictability of turbulence using Lyapunov exponents. Further analysis of the DNS field shows that flow instabilities act on the smallest eddies, and that at any time, there are many sites of local instabilities. DNS, however, is generally too expensive for simulating practical flows. Alternatively, Large Eddy Simulations (LES), in which only the largest scales of turbulent motion are simulated, is more promising as an engineering tool. However, in the near-wall region the large, dynamically important eddies are on the order of viscous scales, which makes resolving them very expensive. It is therefore desirable to formulate an approach in which the near-wall region is modeled, leading to the so-called wall-modeled LES. Spectral analysis of DNS data indicates that thin-film type asymptotics is a promising approach to model the interactions between the near-wall layer and the outer flow. For this approach an asymptotic analysis of the filtered Navier-Stokes equations is pursued in the limit in which the horizontal filter scale is large compared to the thickness of the wall layer. In the second part of this work, we present a new wall model formulated using the asymptotic analysis and insights from DNS data
Author: G. Biswas
Publisher: CRC Press
ISBN: 9780849310140
Category : Technology & Engineering
Languages : en
Pages : 478
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Book Description
This book allows readers to tackle the challenges of turbulent flow problems with confidence. It covers the fundamentals of turbulence, various modeling approaches, and experimental studies. The fundamentals section includes isotropic turbulence and anistropic turbulence, turbulent flow dynamics, free shear layers, turbulent boundary layers and plumes. The modeling section focuses on topics such as eddy viscosity models, standard K-E Models, Direct Numerical Stimulation, Large Eddy Simulation, and their applications. The measurement of turbulent fluctuations experiments in isothermal and stratified turbulent flows are explored in the experimental methods section. Special topics include modeling of near wall turbulent flows, compressible turbulent flows, and more.
