Brinkman number

•  Abbe number

  In physics and optics, the Abbe number, also known as the V-number or constringence of a transparent material, is a measure of the material's dispersion (variation of refractive index with wavelength) in relation to the refractive index. It is named after Ernst Abbe (1840–1905), the German physicist who defined it.

  

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•  Mach number

  Mach number (or) is the speed of an object moving through air, or any fluid substance, divided by the speed of sound as it is in that substance. It is commonly used to represent an object's speed (such as an aircraft or missile), when it is travelling at the speed of sound (or multiples thereof).

  

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•  Pi

  π (sometimes written pi) is a mathematical constant whose value is the ratio of any circle's circumference to its diameter in Euclidean space; this is the same value as the ratio of a circle's area to the square of its radius. It is approximately equal to 3.141593 in the usual decimal notation (see the table for its representation in some other bases). The constant is also known as Archimedes Constant, although this name is rather uncommon in modern, western, English-speaking contexts.

  

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•  Fine-structure constant

  In physics, the fine-structure constant (usually denoted α, the Greek letter alpha) is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction. The numerical value of α is the same in all systems of units, because α is a dimensionless quantity.

  

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•  Dimensionless quantity

  In dimensional analysis, a dimensionless quantity is a quantity without a physical unit and is thus a pure number. Such a number is typically defined as a product or ratio of quantities that might have units individually, but these cancel out in the combination. Dimensionless quantities are widely used in the fields of mathematics, physics, engineering, and economics, but also in everyday life.

  

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•  Power number

  The power number Np (also known as Newton number) is a commonly-used dimensionless number relating the resistance force to the inertia force. The power-number has different specifications according to the field of application. E.g. , for stirrers the power number is defined as: with P: power ρ: fluid density n: rotational speed d: diameter of stirrer

  

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•  Strouhal number

  In dimensional analysis, the Strouhal number is a dimensionless number describing oscillating flow mechanisms. The parameter is named after Vincenc Strouhal, a Czech physicist who experimented in 1878 with wires experiencing vortex shedding and singing in the wind. The Strouhal number is an integral part of the fundamentals of fluid mechanics.

  

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•  Péclet number

  The Péclet number is a dimensionless number relevant in the study of transport phenomena in fluid flows. It is named after the French physicist Jean Claude Eugène Péclet. It is defined to be the ratio of the rate of advection of a physical quantity by the flow to the rate of diffusion of the same quantity driven by an appropriate gradient. In the context of the transport of heat, the Peclet number is equivalent to the product of the Reynolds number and the Prandtl number.

  

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•  Prandtl number

  The Prandtl number is a dimensionless number approximating the ratio of momentum diffusivity and thermal diffusivity. It is named after the German physicist Ludwig Prandtl. It is defined as: where: : kinematic viscosity,, : thermal diffusivity,, : dynamic viscosity, : thermal conductivity, : specific heat, : density, .

  

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•  Nusselt number

  In heat transfer at a boundary (surface) within a fluid, the Nusselt number is the ratio of convective to conductive heat transfer across (normal to) the boundary. Named after Wilhelm Nusselt, it is a dimensionless number. The conductive component is measured under the same conditions as the heat convection but with a (hypothetically) (or motionless) fluid. A Nusselt number close to unity, namely convection and conduction of similar magnitude, is characteristic of "slug flow" or laminar flow.

  

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• Dimensionless numbers by likeorhate
• Fluid dynamics by likeorhate
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•  Onyx

  Onyx is a cryptocrystalline form of quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). Commonly, specimens of onyx available contain bands of colors of white, tan, and brown. Sardonyx is a variant in which the colored bands are sard (shades of red) rather than black. Pure black onyx is common, and perhaps the most famous variety, but not as common as onyx with banded colors.

  

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•  Tromsø Midnight Sun Marathon

  Tromsø Midnight Sun Marathon is the northernmost Association of International Marathons and Distance Races certified marathon in the world. The Midnight Sun Marathon is hosted annually by the Norwegian city of Tromsø in June each year.

  

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•  Yaghnobi language

  The Yaghnobi language is a living East Iranian language. Yaghnobi is spoken in the upper valley of the Yaghnob River in the Zarafshan area of Tajikistan by the Yaghnobi people. It is considered to be a direct descendant of Sogdian and has often been called Neo-Sogdian in academic literature. There are some 12,500 Yaghnobi speakers. They are divided into several communities. The principal group lives in the Zafarobod area. There are also re-settlers in the Yaghnob valley.

  

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•  Vrigne-Meuse

  Vrigne-Meuse is a commune in the Ardennes department in northern France.

  

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