History of the development of fluid mechanics research-2

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History of the development of fluid mechanics research-2

The 17th century, the founder of mechanics Newton to study the resistance to the movement of objects in the fluid, the resistance and fluid density, objects greet flow to the cross-sectional area and the velocity is proportional to the square of the relationship. For the internal friction in the viscous fluid motion, Newton's law of viscosity. However, Newton also not established the theoretical basis of fluid dynamics, he made many of the mechanical model and conclusions with the actual situation there is a large difference. France Pitot invented the pitot tube for measuring flow rate; D'Alembert on the resistance of ships in the canal a lot of experimental work confirmed the square of the relationship between the resistance with the object velocity; the Swiss Euler continuum concept, the concept of pressure in the statics to the movement of fluid, the Euler equation, with the differential equations to describe the inviscid fluid movement; Bernoulli conservation starting from the energy of classical mechanics, the study of water supply pipeline the flow of water, carefully arranged experiments and to analyze the fluid under the steady movement of the relationship between the flow rate, pressure, pipe elevation - the Bernoulli equation.

Euler equation and the Bernoulli equation for fluid dynamics to establish as a branch of the sign, was the beginning of the stage of fluid movement quantitative study of differential equations and experimental measurements. From the 18th century, the potential flow theory has made great progress, wave, tidal, vortex motion, acoustics, clarified the law. French Lagrangian for irrotational motion, the German Helmholtz vortex motion made a lot of research ...... In the above study, the viscosity of the fluid does not play an important role, that is non-sticky fluid. This theory of course, to clarify the viscous effects can not be fluid.

The 19th century, engineers have to solve many engineering problems, to solve the problem with viscous effects. So they part, the use of fluid mechanics, in part, summarized the experimental results of the semi-empirical formula for research, which formed the hydraulics, it still develop in parallel with fluid mechanics. In 1822, the Navier-establish the basic equations of motion of a viscous fluid; 1845, Stokes again more reasonable basis for this equation is derived, and they involve the basic concepts of the macroscopic mechanical demonstration too convincing. These equations is in use since the Navier - Stokes equations (referred to as the NS equations), it is the basis of the theory of fluid dynamics. Mentioned above, the Euler equation is the NS equations in the special case when the viscosity is zero.

The Prandtl School from 1904 to 1921 gradually NS equation has been simplified, reasoning, mathematical arguments and experimental point of view, the establishment of the boundary layer theory, the actual calculation of the simple case, the flow state within the boundary layer and fluid between solid and viscous forces. Planck also proposed many new concepts, and widely applied to the aircraft and turbine design. This theory not only clear the scope of application of the ideal fluid, but also the frictional resistance encountered in the calculation of the movement of objects. So that both cases have been unified.

The early 20th century, the aircraft greatly promoted the development of aerodynamics. The development of the aviation industry, expect to be able to reveal the aircraft around the pressure distribution, force status and resistance of the aircraft, which promote the development of fluid mechanics in the experimental and theoretical analysis. The early 20th century, the Confucian Khodorkovsky, Planck scientists, to create a wing theory of inviscid incompressible fluid potential flow based on the theory, to clarify how the wing will by the lifting force, so that air can sky heavy on the care of the aircraft. Wing theory is correct, a new awareness of the inviscid fluid theory, affirmed the significance of engineering design.

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