HYDRODYNAMIC PROPERTIES OF CONFINED FLUIDS

In the present work, we study the dynamical properties of fluids confi ned at molecular scales. First, we show that, for a fluid confined bet ween two parallel solid walls, the phenomenological hydrodynamic descr iption of bulk fluids holds down to nanoscopic scales, once appropriat e boundary conditions at the solid walls are applied. Then, we investi gate the influence of confinement on the self-diffusion coefficient (i n the direction parallel to the walls) in a fluid slab. We have comput ed the effect of confinement on the mode-coupling contribution to the diffusion coefficient. These finite-size corrections are shown to redu ce the diffusion constant by an amount -(sigma/h) log(h/sigma), where h is the thickness of the fluid slab and a the atomic size. This behav iour can be interpreted in terms of the suppression of long-wavelength modes in the backflow effect, due to confinement.