Relaxation Time and Mean Free Path
The relation between the scattering time,
τ
, and the more familiar mean free path,
λ
, is nontrivial in general. For molecules traveling at a specific lattice velocity,
ξ
i
, the mean free path can be defined as
The Transitional Flow interface includes a mean free path variable defined as the velocity space average of the mean free path. This is given by:
This variable can differ from kinetic theory definitions of the mean free path based on the viscosity and number density, due to the approximations inherent in representing the velocity space by the quadrature.
