What is the term for the absolute viscosity of a fluid divided by its density, expressed in the same units?

The absolute viscosity of a fluid refers to its internal resistance to flow, while density indicates the mass per unit volume of the fluid. When you divide the absolute viscosity by the density of the fluid, the result is termed kinematic viscosity. This quantity is expressed in specific units, typically square meters per second (m²/s) or in centistokes (cSt), where 1 cSt is equal to 10⁻⁶ m²/s. Kinematic viscosity is crucial in characterizing fluid flow and is used extensively in engineering applications to predict how fluids behave in various operations, such as in pipelines, lubrication of machinery, and fluid dynamics.

In some contexts, kinematic viscosity provides a more practical understanding of how a fluid will flow under the influence of gravity compared to its absolute viscosity. This distinction is important in machine design, where the choice of fluids and their behavior under different conditions significantly affects system performance.