What is Viscosity?

What is Viscosity?

The kinematic viscosity in mm2/s is a measure of the internal friction of gases and liquids. It represents the resistance to movement of the contact surfaces of adjoining layers of different (external friction) or identical (internal friction, viscosity) material.

The viscosity depends on pressure and temperature, and decreases with increasing temperature. Its value is measured at +20 °C from the rate of efflux from capillaries or speed at which balls sink in test fluids.