Fluid Mechanics Essay

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The science of fluid mechanics is neither new nor biblical; however, most of the progress in this field was made in the 20th century. Therefore it is appropriate to open this text with a brief history of the discipline, with only a very few names mentioned. As far as we can document history, fluid dynamics and related engineering were always integral parts of human evolution. Ancient civilizations built ships, sails, irrigation systems, and flood-management structures, all requiring some basic understanding of fluid flow. Perhaps the best known early scientist in this field is Archimedes of Syracuse (287–212 b.c.e.), founder of the field now we call “fluid statics,” whose laws on buoyancy and flotation are used to this day. A major leap in understanding fluid mechanics began with the European Renaissance of the 14th–17th centuries. The famous Italian painter–sculptor, Leonardo da Vinci (1452–1519), was one of the first to document basic laws such as the conservation of mass. He sketched complex flow fields, suggested feasible configurations for airplanes, parachutes, and even helicopters, and introduced the principle of streamlining to reduce drag. During the next couple of hundred years, the sciences were gradually developed and then suddenly accelerated by the rational mathematical approach of an Englishman, Sir Isaac Newton (1642–1727), to physics. Apart from the basic laws of mechanics, and particularly the second law connecting acceleration with force, the concepts for drag and shear in a moving fluid were developed by Newton, and his principles are widely used today. The foundations of fluid mechanics really crystallized in the 18th century. One of the more famous scientists, Daniel Bernoulli (1700–1782, Dutch-Swiss), point... ... middle of paper ... ...e following subsections, only a few, which are used in introductory fluid mechanics, are mentioned. Density Density, by definition, is mass per unit volume. In the case of fluids, we can define the density (with the aid of Fig. 1.3) as the limit of this ratio when a measuring volume V shrinks to zero. We need to use this definition because density can change from one point to the other. Also in this picture, we can relate to a volume element in space that we can call “control volume,” which moves with the fluid or can be stationary (in any case it is better to place this control volume in inertial frames of reference). Therefore the definition of density at a point is ρ = lim V→0 _m V _ Typical units are kilograms per cubic meter (kg/m3) or grams per cubic centimeter (g/cm3). m V Control volume Figure 1.3. Mass m in a control volume V. Density is the ratio of m/V.

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