# Kinematic Viscosity

Written by Jerry Ratzlaff. Posted in Fluid Mechanics

Kinematic viscosity is the ratio of dynamic viscosity to density.

The US Customary Measurement for kinematic viscosity is stokes (abbreviated $$S$$ or $$St$$), named after George Gabriel Stokes. It is sometimes expressed in terms of centistokes $$(cS \;or\; cSt)$$. In U.S. usage, stoke is sometimes used as the singular form.

$$1 St = 1 cm^2·s^{−1} = 10^{−4} m^2·s^{−1}$$

1 centistokes = 1 mm2/s

In natural gas engineering work, the kinematic viscosity is not normally used. Instead absolute viscosity is used.

## formula

$$\nu = \frac {\mu} {\rho}$$

Where:

$$\nu$$ (Greek symbol nu) = kinematic viscosity

$$\mu$$ (Greek symbol mu) = dynamic viscosity

$$\rho$$ (Greek symbol rho) = density