Journal article

Velocity profile in the Knudsen layer according to the Boltzmann equation

Charles R Lilley, John E Sader

Proceedings of the Royal Society A: Mathematical, Physical & Engineering Sciences | The Royal Society | Published : 2008


Flow of a dilute gas near a solid surface exhibits non-continuum effects that are manifested in the Knudsen layer. The non-Newtonian nature of the flow in this region has been the subject of a number of recent studies suggesting that the so-called ‘effective viscosity’ at a solid surface is half that of the standard dynamic viscosity. Using the Boltzmann equation with a diffusely reflecting surface and hard sphere molecules, Lilley & Sader discovered that the flow exhibits a striking power-law dependence on distance from the solid surface where the velocity gradient is singular. Importantly, these findings (i) contradict these recent claims and (ii) are not predicted by existing high-order h..

View full abstract

University of Melbourne Researchers


Citation metrics