On Gaseous Self-Diffusion in Long Capillary Tubes

Molecular transport in nanopores

“…The above values of the friction coefficient would appear to be consistent with classical momentum transfer arguments, 9,21 adapted for the presence of intermolecular interactions. Given the high densities in the surface layer ͑cf.…”

“…19 The concept of surface slip, in the context of ideal gas flow and related to superposition of diffusive and viscous transport has been discussed in the early literature. 20,21 The early work, pioneered by Knudsen, 9 concentrated on gaseous flow where the potential energy of interaction between the flowing molecules and the pore wall makes a zero or negligible contribution to the Hamiltonian. Classical kinetic theory was employed to determine the transport coefficient by considering trajectories of molecules following collision with the tube wall or with other molecules.…”

“…Classical kinetic theory was employed to determine the transport coefficient by considering trajectories of molecules following collision with the tube wall or with other molecules. 21 The resulting theoretical picture is one of diffusive flow at low densities, where viscous flow is negligible, with increasingly important contributions from intermolecular collisions at higher density. When viscous flow in the pore becomes significant the diffusive component arising from molecule-wall collisions takes on the role of a slip flow at the boundary.…”

Modelling Binary, Knudsen and Transition Regime Diffusion Inside Complex Porous Media

“…Bosanquet [6] suggested that in the intermediate regime, the collision frequency is simply additive, i. e. :…”

Flow of a rarefied gas induced by thermal gradient and thermo-molecular pressure effect in a circular tube.

“…Regarding the flow as a diffusive process and introducing the diffusivity DP, Eq. (14) can be rewritten as l/DP=l/DPX+ l/DPS (15) where DPK =2C*RI(nllWi) and DPS =C*2/(x1/2hm).…”