Practical Introduction to Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) has become an emerging field in engineering since the early 1980s. The outbreak of personal computers during that era has revolutionized engineering practice in many industries and started a technology race between software companies to develop engineering analysis and simulation software for a wide range of applications. Fluid dynamics is crucially important to almost all engineering applications; from automotive and process engineering to power generation and defense industries. Hence, it was natural for CFD to be within the core of the global quest to develop and possess accurate and reliable simulation software As a result, CFD has become a very important analysis tool, as well as area of research, in academia. Since it involves mathematical modeling, numerical analysis, physics and scientific computing, CFD is an ideal example of interdisciplinary research areas. Mathematicians, physicists, engineers and computer scientists found great passion in developing new CFD tools and improve the state of the art codes. However, as it is common in similar interdisciplinary fields, the boundaries between these specializations are indefinite, dynamic, and sometimes vague. Mechanical engineers who wish to make use of the powerful CFD tools today must leave their comfort zone of empirical and closed form correlations to get into differential calculus, numerical analysis, and scientific computing. Mathematicians who aim at improving the state of the art discretization schemes must understand the physics of turbulent flow and chemical reactions. Computer scientists who wish to employ the increasing power of Graphical Processing Units in CFD should understand the nature of initial-boundary problems encountered in CFD to know the type of matrices they yield. As a result, text and reference books of CFD attempt to demonstrate such interdisciplinary nature of the field. Unlike the classic books of the 1980s and 1990s, modern CFD books do discuss state of the art methods implemented in general purpose codes.
These notes is an attempt to provide mechanical engineers with a practical resource of the fundamentals of CFD to enable complete understanding of the most common CFD methods used in mechanical engineering applications today. The notes are interdisciplinary of course, however, only the boundaries that interest junior mechanical engineers were followed. The first two chapters provide the mathematical foundations of differential analysis of fluid flow and its governing equations. The third chapter sheds the light on the most commonly used discretization method in today’s general purpose CFD codes; the finite volume method. Chapter four provides the reader with the essential elements of a CFD solver, such that their suitability for the problems usually encountered in mechanical engineering practice is understood. Chapter five introduces the reader to turbulence modeling, and focuses on the most commonly used models which are eddy viscosity models. In chapter six, the reader learns about the reliability assessment of CFD simulations through verification and validation practices. Chapter seven gives a brief introduction about modeling of combustion systems using CFD, and chapter eight provides practical examples using ANSYS Fluent®.

Khalid M. Saqr, Ph.D.
Alexandria, 2015
Alexandria, 2017