viscosity of air implementation really the best available?
The current implementation of air viscosity is taken from the Book [Properties of Gases & Liquids] and uses a method which can be applied to estimate viscosities for polar substances. But air contains mainly non-polar molecules. Thus, I wonder if this relatively complex approach is really justified or if it is really the most accurate available. The ''old'' implementation in MUFTE is currently still used as simpleGasViscosity, but as far as I remember, this was specific for dry air. VDI-Wärmeatlas contains exact values for dry air viscosity. We could compare the current implementations or implement a new one if necessary based on the tables there.