Assessment of Closure Coefficients for Compressible-Flow Turbulence Models


Book Description

A critical assessment is made of the closure coefficients used for turbulence length scale in existing models of the transport equation, with reference to the extension of these models to compressible flow. It is shown that to satisfy the compressible 'law of the wall', the model coefficients must actually be functions of density gradients. The magnitude of the errors that result from neglecting this dependence on density varies with the variable used to specify the length scale. Among the models investigated, the k-omega model yields the best performance, although it is not completely free from errors associated with density terms. Models designed to reduce the density-gradient effect to an insignificant level are proposed. Huang, P. G. and Bradshaw, P. and Coakley, T. J. Ames Research Center NASA-TM-103882, A-91212, NAS 1.15:103882 RTOP 505-59-53...










Prediction of Turbulent Flows


Book Description

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.




Fundamentals of Turbulent and Multiphase Combustion


Book Description

Detailed coverage of advanced combustion topics from the author of Principles of combustion, Second Edition Turbulence, turbulent combustion, and multiphase reacting flows have become major research topics in recent decades due to their application across diverse fields, including energy, environment, propulsion, transportation, industrial safety, and nanotechnology. Most of the knowledge accumulated from this research has never been published in book form—until now. Fundamentals of Turbulent and Multiphase Combustion presents up-to-date, integrated coverage of the fundamentals of turbulence, combustion, and multiphase phenomena along with useful experimental techniques, including non-intrusive, laser-based measurement techniques, providing a firm background in both contemporary and classical approaches. Beginning with two full chapters on laminar premixed and non-premixed flames, this book takes a multiphase approach, beginning with more common topics and moving on to higher-level applications. In addition, Fundamentals of Turbulent and Multiphase Combustion: Addresses seven basic topical areas in combustion and multiphase flows, including laminar premixed and non-premixed flames, theory of turbulence, turbulent premixed and non-premixed flames, and multiphase flows Covers spray atomization and combustion, solid-propellant combustion, homogeneous propellants, nitramines, reacting boundary-layer flows, single energetic particle combustion, and granular bed combustion Provides experimental setups and results whenever appropriate Supported with a large number of examples and problems as well as a solutions manual, Fundamentals of Turbulent and Multiphase Combustion is an important resource for professional engineers and researchers as well as graduate students in mechanical, chemical, and aerospace engineering.




Compressibility, Turbulence and High Speed Flow


Book Description

Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current trends. - An introduction to current techniques in compressible turbulent flow analysis - An approach that enables engineers to identify and solve complex compressible flow challenges - Prediction methodologies, including the Reynolds-averaged Navier Stokes (RANS) method, scale filtered methods and direct numerical simulation (DNS) - Current strategies focusing on compressible flow control




Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.




Computational Fluid Dynamics for Built and Natural Environments


Book Description

This book introduces readers to the fundamentals of simulating and analyzing built and natural environments using the Computational Fluid Dynamics (CFD) method. CFD offers a powerful tool for dealing with various scientific and engineering problems and is widely used in diverse industries. This book focuses on the most important aspects of applying CFD to the study of urban, buildings, and indoor and outdoor environments. Following the logical procedure used to prepare a CFD simulation, the book covers e.g. the governing equations, boundary conditions, numerical methods, modeling of different fluid flows, and various turbulence models. Furthermore, it demonstrates how CFD can be applied to solve a range of engineering problems, providing detailed hands-on exercises on air and water flow, heat transfer, and pollution dispersion problems that typically arise in the study of buildings and environments. The book also includes practical guidance on analyzing and reporting CFD results, as well as writing CFD reports/papers.




Improved Turbulence Models Based on Large Eddy Simulation of Homogeneous, Incompressible, Turbulent Flows


Book Description

The physical bases of large eddy simulation and the subgrid scale modeling it employs are studied in some detail. This investigation leads to a new scale-similarity model for the subgrid-scale turbulent Reynolds stresses.




Aeronautics and Astronautics


Book Description

These conference proceedings present 165 papers in all scientific and aerospace engineering fields, including materials and structures, aerodynamics and fluid dynamics, propulsion, aerospace systems, flight mechanics and control, space systems, and missions. Keywords: Aerospace Shell Structures, MCAST's Aerospace Program, Sandwich Structures, Thermal Buckling, Simulation of Elastodynamic Problems. Statically Deflected Beam, Meshes with Arbitrary Polygons, Variable Stiffness Composite Panels, Mechanical Response of Composites, 3D Printing Technique, Hygrothermal Effects in Composite Materials, Freeze-Thaw Cycling, Polymer Matrices, Morphing Aileron, Thermo-Elastic Homogenization of Polycrystals, Flutter Instability in Elastic Structures, Adaptive Composite Wings, Cylindrical IGA Patches, TRAC Longerons, Structural Damage Detection, Fatigue Behavior of Stiffened Composite Components, Redesign of Composite Fuselage Barrel Components, Damage Modelling of Metallic Lattice Materials, Ceramic Matrix Composites, Peridynamics Elastoplastic Model, Structural Batteries Challenges. Dynamic Buckling Structural Test, Delamination Identification on Composites Panels. CubeSat Radiative Surface, Wind Tunnel Testing.