THE FOUNDER OF MODERN FLUID DYNAMICS: LUDWIG PRANTDL
A fluid is defined as a substance that does not have any determined shape and is deformed continuously by a shear force, thus it can be said that fluid mechanics is considered as a part of physics which is concerning about gases, liquids and plasmas, in the other words, no solid phases.[1] Modern fluid mechanics is based on Continuum Hypothesis. This hypothesis assumes that a matter is continuous, hence while a matter is examined, atomic structure is not regarded- because if a matter is analyzed at a microscopic scale, the matter will be observed as discrete- and macroscopic scale is preferred instead of microscopic scale.[2]
Fluid mechanics can be divided into some subtitles, and these are fluid static (at rest) and fluid dynamic (in motion). These sections of fluid mechanics follow historical progression. In history, Archimedes thought about fluids firstly and his ideas were the entry of fluid static, and then Leonardo Da Vinci examined behaviors of complex flow. The important breakthrough about fluid dynamic appeared thanks to luminaries in Newtonian physics; they are Isaac Newton, Leonhard Euler and Daniel Bernoulli etc. Pressure as being three dimensional and velocity of fluid were explained thanks to Euler equations, but the equations were not enough to clarify the viscosity (friction) in a flow field. In the next century, Euler equations were developed by Claude-Louis Navier and George Stokes independently, and then new equations were derived and nowadays they are known as Navier-Stokes equations. These equations provided to describe internal friction acting in a flow field, but could not explain friction between a flow and a surface which contacts with the flow. The re...
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... the calculations of friction and pressure drag are based on his investigations. After Prandtl, his students could comment the manner of supersonic flow and the turbulent momentum exchange in the help of the boundary layer concept and equations.
References
1) http://www.mne.psu.edu/cimbala/Learning/Fluid/Introductory/what_is_fluid_mechanics.htm
2) Currie, I. G, Fundamental Mechanics of Fluids, McGraw-Hill Inc., (1974)
3) Bruce R. Munson, Theodore H. Okiishi, Wade W. Huebsch, Alric P. Rothmayer, Fluid mechanics 7th edition, Willey, (2013)
4) Genick Bar-Meir, Basic Fluid Mechanics Version 0.3.4.0, http://www.potto.org/FM/fluidMechanics.pdf (2013)
5) John D. Anderson Jr, Ludwig Prandtl’s Boundary Layer, Physics Today (2005)
6) P. Erhard, D. Etling, U. Müller, U. Riedel, K.R. Sreenivasan, J. Warnatz, Prandtl-Essentials Fluid Mechanic 3rd Edition, Sprinker (2008)
They just forgot to mention the other effects of fluids in nature. “The influence of the fluid on a body moving through it depends not only on the body’s velocity but also on the velocity of the fluid,” this is called relative velocity ( ). The relative velocity of a body in a fluid has an effect on the magnitude of the acting forces. For example, as a long distance runner is running into a head wind, the force of the fluid is very strong. If the runner is running with the help of a tail wind, the current’s force is reduced and may even be unnoticeable.
Have you wondered why airplanes were ever able to fly or how racecars are able to stay on the ground at high speeds? They all use a scientific concept called Bernoulli’s principle, or more commonly known as Bernoulli’s equation. His principle simply states that the faster a fluid flows, the less pressure it applies, the slower the fluid flows, the more pressure it applies.
In classical fluid dynamics, the Navier-Stokes equations for incompressible viscous fluids and its special (limiting) case the Euler equations for inviscid fluids are sets of non-linear partial differential equations that describes the spatiotemporal evolution of a fluid (gas). Both equations are derived from conservative principles and they model the behavior of some macroscopic variables namely: mass density, velocity and temperature.
Bernoulli’s principle is the concept that as the speed of a moving fluid (liquid or gas) increases, the pressure within that fluid decreases. This principle was originally formulated in 1738 by the Swiss mathematician and physicist Daniel Bernoulli, it states that the total energy in a steadily flowing ...
Introduction to Aerodynamics Aerodynamics is the study of the motion of fluids in the gas state and bodies in motion relative to the fluid/air. In other words, the study of aerodynamics is the study of fluid dynamics specifically relating to air or the gas state of matter. When an object travels through fluid/air there are two types of flow characteristics that happen, laminar and turbulent. Laminar flow is a smooth, steady flow over a smooth surface and it has little disturbance. Intuition would lead to the belief that this type of air flow would be desirable.
...ion, Scriver CR, Beaudet AL, Sly WS, Valle D (eds), McGraw-Hill, New York, pp. 4353-4392
Trefil, J. S. (1975) Introduction to the physics of fluids and solids (New York: Pergamon Press).
Price, Darby. “Takaki Ch. 1, 4, 5” Engineering Building Room 343, San Jose. 24 February. 2014. Lecture.
This chart shows the relationship between the fanning friction factor and the Reynolds number over a wide range of flow rates, from which the roughness parameter (e/D) for the piping system can be estimated.
[5] Ratliff, Richard L; Beckstead, Stephen M; Hanks, Steven H; Quality Progress; Jun 1999; Pg. 31
On a more scientific note I am interested in mechanics of fluids. This interest was enforced last year when I had the opportunity to attend a lecture on fluid mechanics at P&G. At the conference I greatly expanded my knowledge regarding the physical aspect of fluids and their properties. In last year's AS course we have met a topic in this field. I will be applying ideas and knowledge gathered from last year for this investigation.
Cengel, Y. A., & Boles, M. A. (2011). Thermodynamics: An engineering approach (7th ed.). New York, NY: McGraw-Hill.¬¬¬¬
Since the days of Aristotle, all substances have been classified into one of three physical states. A substance having a fixed volume and shape is a solid. A substance, which has a fixed volume but not a fixed shape, is a liquid; liquids assume the shape of their container but do not necessarily fill it. A substance having neither a fixed shape nor a fixed volume is a gas; gases assume both the shape and the volume of their container. The structures of gases, and their behavior, are simpler than the structures and behavior of the two condensed phases, the solids and the liquids
Liquids have no definite shape. Liquids are less orderly than solids but more orderly than gases. Liquids can flow very easily. Liquids also take the shape of their container.
Physics began when man first started to study his surroundings. Early applications of physics include the invention of the wheel and of primitive weapons. The people who built Stone Henge had knowledge of physical mechanics in order to move the rocks and place them on top of each other. It was not until during the period of Greek culture that the first systematic treatment of physics started with the use of mechanics. Thales is often said to have been the first scientist, and the first Greek philosopher. He was an astronomer, merchant and mathematician, and after visiting Egypt he is said to have originated the science of deductive geometry. He also discovered theorems of elementary geometry and is said to have correctly predicted an eclipse of the sun. Many of his studies were in astronomy but he also observed static electricity. Phythogoras was a Greek philosopher. He discovered simple numerical ratios relating the musical tones of major consonances, to the length of the strings used in sounding them. The Pythagorean theorem was named after him, although this fundamental statements of deductive geometry was most likely first an idea from Egyptian methods of measurements. With the help of his followers he discovered that the earth was a sphere, but he did not believe it revolved around the sun.