Use the Flow Properties node to define the parameters for the Boltzmann BGK model. The dynamic viscosity, the temperature, and the mean molar mass must be specified. These parameters define the relaxation time, τ, the characteristic molecular speed, cs, and the molecular mass, m, which are the fundamental material parameters in the BGK model.

The default Dynamic viscosity μ (SI unit: Pa·s) uses the value From material. For User defined define a different value or expression.

The default Mean molar mass Mn (SI unit: kg/mol) is User defined with a default value of 0.028 kg/mol.