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2019 | Book

Applied Computational Fluid Dynamics and Turbulence Modeling

Practical Tools, Tips and Techniques

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About this book

This unique text provides engineering students and practicing professionals with a comprehensive set of practical, hands-on guidelines and dozens of step-by-step examples for performing state-of-the-art, reliable computational fluid dynamics (CFD) and turbulence modeling. Key CFD and turbulence programs are included as well. The text first reviews basic CFD theory, and then details advanced applied theories for estimating turbulence, including new algorithms created by the author. The book gives practical advice on selecting appropriate turbulence models and presents best CFD practices for modeling and generating reliable simulations. The author gathered and developed the book’s hundreds of tips, tricks, and examples over three decades of research and development at three national laboratories and at the University of New Mexico—many in print for the first time in this book. The book also places a strong emphasis on recent CFD and turbulence advancements found in the literature over the past five to 10 years. Readers can apply the author’s advice and insights whether using commercial or national laboratory software such as ANSYS Fluent, STAR-CCM, COMSOL, Flownex, SimScale, OpenFOAM, Fuego, KIVA, BIGHORN, or their own computational tools.

Applied Computational Fluid Dynamics and Turbulence Modeling is a practical, complementary companion for academic CFD textbooks and senior project courses in mechanical, civil, chemical, and nuclear engineering; senior undergraduate and graduate CFD and turbulence modeling courses; and for professionals developing commercial and research applications.

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
The motivation for learning and mastering CFD and turbulence modeling is based on their ever-increasing potential to solve problems, especially those that cannot be resolved experimentally due to physical limitations, economic cost, safety, time constraints, or environmental regulatory procedures. Current and future employment trends, computational capacity growth, and experimentation costs favor CFD. The integration of CFD, theory, advanced manufacturing, and experiments will lead towards even more economical and faster development of prototypes and systems for more streamlined concept-to-market development. As Moore’s law eventually ceases to apply, quantum and nano-computing devices, as well as quantum algorithms, will continue the computational growth trend for many decades to come, if not centuries. The near future holds the potential for simulations that are thousands of times faster than is currently feasible. This fascinating subject is elaborated further in Sect. 5.2.
Sal Rodriguez
Chapter 2. Overview of Fluid Dynamics and Turbulence
Abstract
The first part of the chapter provides a review for mass, momentum, and energy conservation, as well as turbulence theory and modeling. Then, the historical development and importance of the Reynolds number (Re) is firmly established, leading to guidelines for calculating Re for many useful engineering geometries. Fully developed laminar and turbulent flow is described, as well as insights regarding the turbulent kinematic viscosity. Finally, isotropic turbulence and Taylor eddy theory are introduced, to lay a foundation regarding their merit and practical applications in CFD modeling; this development culminates in Sect. 3.7, where numerous practical drag reduction and heat transfer applications are described in more detail.
Sal Rodriguez
Chapter 3. Applied Theory: Practical Turbulence Estimates
Abstract
The three key eddies are described in detail, with practical equations to calculate their length, life time, and velocity. The LIKE algorithm is presented to compute key turbulence parameters. Flow regions are defined and represented mathematically for the viscous laminar sublayer and the log laws. Detailed descriptions for calculating y+ are presented. The chapter concludes with a detailed description for dimpling and surface engineering applicable for drag reduction and heat transfer enhancements. Both compressible and incompressible applications are discussed; examples include golf balls, shark skin, vehicle surfaces, heat transfer systems, wings and airfoils, turbulators, and diverse dimple geometries.
Sal Rodriguez
Chapter 4. RANS Turbulence Modeling
Abstract
The turbulent kinetic energy equation is derived and explained in full detail. The motivation and development of RANS-based models is provided, with the aim of generating a deeper understanding of turbulence phenomena. This includes the detailed descriptions for key k-ε, k-ω, and SST hybrid models. Fundamental RANS terms are explained, such as turbulent kinematic viscosity, production, and decay. RANS models are evaluated and compared, and the best overall turbulence model is suggested. Model applicability, best performance regions, and deficiencies are discussed for zero-, one-, and two-equation RANS models. Compelling reasons for avoiding the standard k-ε are provided. Multiple insights regarding ties associated with the development of k-ε and k-ω models are presented, such as the Taylor scale and eddy dissipation.
Sal Rodriguez
Chapter 5. LES and DNS Turbulence Modeling
Abstract
This chapter is divided into two parts, LES and DNS. In the first part, the LES turbulence model is derived from first principles, and its terms are described in detail. The usage of LES filters is described, along with various recommendations. The LIKE algorithm is applied to show how to model large eddies properly by applying the appropriate node-to-node computational distances. LES-specific boundary and initial conditions are described, and dozens of practical recommendations are provided. In the second part, analogous discussions and recommendations for DNS are included as well.
Sal Rodriguez
Chapter 6. Best Practices of the CFD Trade
Abstract
A strong attempt is made to provide practical guidelines for CFD meshes. Dozens of mesh metrics are described in detail, and a mathematically-driven, physics-based set of “golden” mesh metrics is recommended. General CFD boundary and initial conditions are described, including boundary compatibility. Time step, stability, domain, and calculation speed-up guidelines are provided. Detailed guidelines for modeling laminar and turbulent natural circulation are discussed. The chapter concludes with dozens of data visualization recommendations for generating figures, movies, and other presentation media, with the goal of more effectively conveying the CFD results.
Sal Rodriguez
Chapter 7. Listing for Turbulence Programs, Functions, and Fragments
Abstract
A compilation of MATLAB scripts and functions is provided to enable the user to quickly estimate key laminar and turbulence parameters. This includes the LIKE algorithm, as well as a function to calculate physical properties for various molten metals. Another MATLAB script calculates the peak velocity for laminar and turbulent flows under natural circulation. The script also calculates the convective heat transfer coefficient, Pr, Gr, Nu, and Ra. Finally, a FORTRAN program for the Prandtl one-equation turbulence model is provided. The program is intended as an example to show how RANS models can be coded, as well as to provide some practical guidelines. The program couples the momentum equation with the k PDE to solve a 2D Couette flow. For user convenience, the program writes MATLAB files suitable for plotting k, ε, νt, and \( \overline{u} \).
Sal Rodriguez
Backmatter
Metadata
Title
Applied Computational Fluid Dynamics and Turbulence Modeling
Author
Sal Rodriguez
Copyright Year
2019
Electronic ISBN
978-3-030-28691-0
Print ISBN
978-3-030-28690-3
DOI
https://doi.org/10.1007/978-3-030-28691-0

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