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Kinematic Viscosity

Figure 1.8. Air viscosity as a function of the temperature.

The kinematic viscosity is another way to look at the viscosity. The reason for this new definition is that some experimental data are given in this form. These results also explained better using the new definition. The kinematic viscosity embraces both the viscosity and density properties of a fluid. The above equation shows that the dimensions of \(\nu\) to be square meter per second, \([m^2 / sec]\), which are acceleration units (a combination of kinematic terms). This fact explains the name ``kinematic'' viscosity. The kinematic viscosity is defined as \[\nu = \frac{\mu}{\rho}\tag{19}\] The gas density decreases with the temperature. However, The increase of the absolute viscosity with the temperature is enough to overcome the increase of density and thus, the kinematic viscosity also increase with the temperature for many materials.

Fig. 1.9. Water viscosity as a function of temperature.