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Stokes–Einstein–Sutherland equation, for diffusion of spherical particles through a liquid with low Reynolds number: = Here q is the electrical charge of a particle; μ q is the electrical mobility of the charged particle; η is the dynamic viscosity;
Intrinsic viscosity [] is a measure of a solute's contribution to the viscosity of a solution.If is the viscosity in the absence of the solute, is (dynamic or kinematic) viscosity of the solution and is the volume fraction of the solute in the solution, then intrinsic viscosity is defined as the dimensionless number [] = It should not be confused with inherent viscosity, which is the ratio of ...
The poise is often used with the metric prefix centi-because the viscosity of water at 20 °C (standard conditions for temperature and pressure) is almost exactly 1 centipoise. [3] A centipoise is one hundredth of a poise, or one millipascal-second (mPa⋅s) in SI units (1 cP = 10 −3 Pa⋅s = 1 mPa⋅s). [4] The CGS symbol for the centipoise ...
The three viscosity equations now coalesce to a single viscosity equation = = because a nondimensional scaling is used for the entire viscosity equation. The standard nondimensionality reasoning goes like this: Creating nondimensional variables (with subscript D) by scaling gives
For instance, a 20% saline (sodium chloride) solution has viscosity over 1.5 times that of pure water, whereas a 20% potassium iodide solution has viscosity about 0.91 times that of pure water. An idealized model of dilute electrolytic solutions leads to the following prediction for the viscosity μ s {\displaystyle \mu _{s}} of a solution: [ 57 ]
The Stokes-Einstein equation describes a frictional force on a sphere of diameter as = where is the viscosity of the solution. Inserting this into 9 gives an estimate for k D {\displaystyle k_{D}} as 8 R T 3 η {\displaystyle {\frac {8RT}{3\eta }}} , where R is the gas constant, and η {\displaystyle \eta } is given in centipoise.
The Einstein field equations (EFE) may be written in the form: [5] [1] + = EFE on the wall of the Rijksmuseum Boerhaave in Leiden, Netherlands. where is the Einstein tensor, is the metric tensor, is the stress–energy tensor, is the cosmological constant and is the Einstein gravitational constant.
The Stokes radius or Stokes–Einstein radius of a solute is the radius of a hard sphere that diffuses at the same rate as that solute. Named after George Gabriel Stokes , it is closely related to solute mobility, factoring in not only size but also solvent effects.