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Extensional viscosity can be measured with various rheometers that apply extensional stress. Volume viscosity can be measured with an acoustic rheometer. Apparent viscosity is a calculation derived from tests performed on drilling fluid used in oil or gas well development. These calculations and tests help engineers develop and maintain the ...
Volume viscosity (also called bulk viscosity, or second viscosity or, dilatational viscosity) is a material property relevant for characterizing fluid flow. Common symbols are ζ , μ ′ , μ b , κ {\displaystyle \zeta ,\mu ',\mu _{\mathrm {b} },\kappa } or ξ {\displaystyle \xi } .
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.
(dynamic) viscosity (also ) pascal second (Pa⋅s) theta: angular displacement: radian (rad) kappa: torsion coefficient also called torsion constant newton meter per radian (N⋅m/rad) lambda: cosmological constant: per second squared (s −2)
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A series of steel ball bearings of different diameters are normally used in the classic experiment to improve the accuracy of the calculation.
Flux F through a surface, dS is the differential vector area element, n is the unit normal to the surface. Left: No flux passes in the surface, the maximum amount flows normal to the surface.
From the Stokes equation, when the volume of fluid is sinking, viscous drag is of the order , where is the dynamic viscosity of the fluid. When these two forces are equated, the speed u ∼ Δ ρ l 2 g / η {\displaystyle u\sim \Delta \rho l^{2}g/\eta } .