Related Resources: fluid flow

### Kinematic Viscosity Equation Application

The kinematic viscosity ν is the ratio of the viscosity to the density. The SI unit of kinematic viscosity is m2/s.

Kinematic Viscosity = (Dynamic Viscosity) / Density

v = u/p

Centostokes = Centipoise / Density

Where:

v = Kinematic Viscosity (m2/s) -> Kinematic Viscosity Table Chart of Liquids
u = Dynamic Viscosity (N s/m2)
p = Density (kg/m3)

Kinematic Viscosity = v = u/p = (kg/(m x s) x 10-3) / (kg/m3) = m2/s x 10-6

The cgs physical unit for kinematic viscosity is the stokes (St), named after George Gabriel Stokes. It is sometimes expressed in terms of centistokes (cSt). In U.S. usage, stoke is sometimes used as the singular form.

1 St = 1 cm2·s−1 = 10−4 m2·s−1.
1 cSt = 1 mm2·s−1 = 10−6 m2·s−1.
1 m2/s = 10000 Stokes = 1000000 Centistokes

Water at 20 °C has a kinematic viscosity of about 1 cSt.

The kinematic viscosity is sometimes referred to as diffusivity of momentum, because it is analogous to diffusivity of heat and diffusivity of mass. It is therefore used in dimensionless numbers which compare the ratio of the diffusivities.

Kinematic Viscosty of Selected Petroleum Fluids  