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Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes. For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3.
The proportionality factor is the dynamic viscosity of the fluid, often simply referred to as the viscosity. It is denoted by the Greek letter mu ( μ ). The dynamic viscosity has the dimensions ( m a s s / l e n g t h ) / t i m e {\displaystyle \mathrm {(mass/length)/time} } , therefore resulting in the SI units and the derived units :
η is the air dynamic viscosity, Pa·s Q is the flowrate, m 3 ·s −1. It can be seen that the specific surface is proportional to the square root of the ratio of pressure to flow. Various standard methods have been proposed: Maintain a constant flowrate, and measure the pressure drop; Maintain a constant pressure drop, and measure the flowrate
The poise (symbol P; / p ɔɪ z, p w ɑː z /) is the unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units (CGS). [1] It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the poise itself.
Other names are sometimes employed for one or both parameters, depending on context. For example, the parameter μ is referred to in fluid dynamics as the dynamic viscosity of a fluid (not expressed in the same units); whereas in the context of elasticity, μ is called the shear modulus, [2]: p.333 and is sometimes denoted by G instead of μ.
The dilute gas viscosity contribution to the total viscosity of a fluid will only be important when predicting the viscosity of vapors at low pressures or the viscosity of dense fluids at high temperatures. The viscosity model for dilute gas, that is shown above, is widely used throughout the industry and applied science communities.
calorie (International Table) cal IT: ≡ 4.1868 J = 4.1868 J: calorie (mean) cal mean: 1 ⁄ 100 of the energy required to warm one gram of air-free water from 0 °C to 100 °C at a pressure of 1 atm ≈ 4.190 02 J: calorie (thermochemical) cal th: ≡ 4.184 J = 4.184 J: Calorie (US; FDA) Cal ≡ 1 kcal = 1000 cal = 4184 J: calorie (3.98 °C ...
the fluid is assumed to be isotropic, as with gases and simple liquids, and consequently is an isotropic tensor; furthermore, since the deviatoric stress tensor is symmetric, by Helmholtz decomposition it can be expressed in terms of two scalar Lamé parameters, the second viscosity and the dynamic viscosity, as it is usual in linear elasticity: