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Power-law viscosity law

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A power-law can be used as an approximation of the viscosity of dilute gases. For dilute gases at moderate temperatures this formula is slightly less accurate than Sutherland's law. The power-law viscosity law can be written as:

\mu = BT^n

Where \mu is the viscosity in kg/m-s, T is the static temperature in K, and B is a dimensional coefficient. For air at moderate temperatures and pressures B = 4.093 \times 10^{-7}, and n = 2/3.

The power-law viscosity law can also be written as:

\mu = \mu_{ref} \left(\frac{T}{T_{ref}}\right)^n

Where \mu is the viscosity in kg/m-s, T is the static temperature in K, T_{ref} is a reference value in K, \mu_{ref} is a reference value in kg/m-s. For air at moderate temperatures and pressures, \mu_{ref} = 1.716\times 10^{-5} kg/m-s, T_{ref} = 273 K, and n = 2/3.

Note that there exists a different power-law for non-Newtonian fluids!

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