kinetic viscosity

physics

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June 30, 2026

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Kinetic viscosity is a measure used in fluid mechanics, representing the ratio of a fluid's dynamic viscosity to its mass density. It quantifies the fluid's resistance to flow when subjected to gravity.1

Dynamic viscosity, often simply called viscosity, is the resistance of a fluid to deformation or flow. Think of molasses having a higher viscosity than water. This internal friction between fluid molecules opposes differences in velocity within the fluid.2

The unit for dynamic viscosity is the pascal-second (Pa·s) in the International System of Units (SI). Kinetic viscosity's dimensions are area divided by time, with the SI unit being square meters per second (m²/s). For example, water has a kinetic viscosity of approximately 10⁻⁶ m²/s at standard conditions.231

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fluid mechanics
Measurement of shear viscosity
The kinetic viscosity at normal temperatures and pressures is about 10⁻⁶ square metre per second for water and about 1.5 × 10⁻⁵ square metre per second for air.
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The kinetic viscosity at normal temperatures and pressures is about 10⁻⁶ square metre per second for water and about 1.5 × 10⁻⁵ square metre per second for air.
Read More