Chapter 2

Fluid mechanics concepts


This chapter sets out some basic fluid mechanics concepts that are required in the study of train aerodynamics and that will be referred to later in this book. Dimensionless analysis and dimensionless variables are described, and this is followed by a discussion of two different frames of reference – the ground and train frames. Qualitative descriptions are then given of the principles of conservation of mass, momentum and energy, and of the concepts of free flows, boundary layers, turbulence, separated flows and wakes. This leads into a more quantitative discussion of the equations of motion in a variety of different forms, which will all be referred to later in this book. This section attempts to show ...

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