2. Aerodynamic lubrication. Air viscosity

Air is the main lubricant considered in this article, although other compressible fluids can also be used (hydrogen, oxygen, nitrogen, etc.). For the purposes of aerodynamic lubrication, air is considered an ideal gas that obeys the equation of state :

where r = 287.03 m ² /s ² /K

and undergoes isothermal evolution.

Under these conditions, the main property of air is its compressibility (∂ ρ /∂P ) _T / ρ which is of the order of 10 ^...