On the validity of hydrodynamics in plane Poiseuille flows

Microscopic simulations of plane Poiseuille flow for a dilute gas are presented. Although the flow is laminar (Reynolds number ≈10) and sub-sonic, the temperature and pressure profiles measured in the simulations differ qualitatively from the hydrodynamic predictions. The results are in agreement with a recent theoretical analysis based on the asymptotic solution of the BGK model of the Boltzmann equation.