Fluid mechanics is the study of fluids either in motion (fluid dynamics) or at rest (fluid statics). Both gases and liquids are classified as fluids, and the number of fluid engineering applications is enormous: breathing, blood flow, swimming, pumps, fans, turbines, airplanes, ships, rivers, windmills, pipes, missiles, icebergs, engines, filters, jets, and sprinklers, to name a few. When you think about it, almost everything on this planet either is a fluid or moves within or near a fluid.
The essence of the subject of fluid flow is a judicious compromise between theory and experiment. Since the fluid flow is a branch of mechanics, it satisfies a set of well-documented basic laws, and thus a great deal of theoretical treatment is available. However, the theory is often frustrating because it applies mainly to idealized situations, which may be invalid in practical problems. The two chief obstacles to a workable theory are geometry and viscosity. The basic equations of fluid motion are too difficult to enable the analyst to attack arbitrary geometric configurations. Thus this course will concentrate on flat plates, circular pipes, and other easy geometries. The viscosity increases the difficulty of the basic equations, although the boundary-layer approximation found by Ludwig Prandtl in 1904 has greatly simplified viscous-flow analyses. Second, viscosity has a destabilizing effect on all fluids, giving rise, at frustratingly small velocities, to a disorderly, random phenomenon called turbulence.
The theory of turbulent flow is crude and heavily backed up by experiments, yet it can be quite serviceable as an engineering estimate. This course is limited to an introduction to boundary layer and turbulence.
Often the experimental data provide the main source of information about specific flows, such as the drag and lift of immersed bodies. Fortunately, fluid mechanics is a highly visual subject, with good instrumentation, and the use of dimensional analysis and modeling concepts is widespread. Thus experimentation provides a natural and easy complement to the theory. You should keep in mind that theory and experiment should go hand in hand in all studies of fluid mechanics. This course will cover in detail the concepts of dimensional analysis and similitudes too.