Computational fluid dynamics (CFD) is concerned with the numerical solution of differential equations governing the fluid flow, heat transfer, and associated phenomena such as chemical reactions by means of computer-based simulation. CFD activity emerged and gained prominence with the availability of computers in the early 1960s. Since the early 1970s, commercial software packages become available made CFD a powerful dominant technique spanning a wide range of industrial and nonindustrial application areas.
CFD has several unique advantages over experiments to design fluid systems:
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It reduces the lead times and costs of new designs substantially.
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It is able to study the systems where controlled experiments are difficult or impossible to perform.
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It is capable of studying systems under hazardous conditions at their normal performance limits and beyond.
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It gives results with an unlimited level of detail.
CFD is a highly interdisciplinary research area that lies at the interface of physics, applied mathematics, and computer science. The main components of a CFD design cycle are as follows:
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Analyst who states the problem to be solved
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Scientific knowledge expressed mathematically including models, methods, etc.
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Software (computer code) that embodies this knowledge and provides the related algorithms
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Computer hardware that performs the actual calculations and
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Again, the analyst who analyses and interprets the simulation results.
Hence all codes contain three main elements: (1) preprocessor, (2) solver, and (3) postprocessor. In CFD, the governing equations are discretized on grid pints (using finite difference method, finite volume method, finite element method, etc.) and transformed into a set of linear algebraic equations, which are solved to give the results.
In this chapter, an introduction to the principle of CFD is presented. The main focus is put on the overall solution process for a partial differential equation, finite difference, and finite volume methods and associated discretization schemes, solution algorithms, grid generation, and solution methods for algebraic equations.