HYDRODYNAMIC BOUNDARY-CONDITIONS AND CORRELATION-FUNCTIONS OF CONFINED FLUIDS

A phenomenological description of the dynamical correlations in a flui d confined between two parallel solid walls, using a generalization of Onsager's theory of fluctuations, is presented. Besides the bulk visc osity, this description involves parameters characterizing the boundar y conditions. Correlation functions obtained in equilibrium molecular dynamics simulations are very well described within this framework. Fe atureless walls yield perfect slip boundary conditions, while corrugat ed walls in most cases correspond to stick boundary conditions. Only f or very small corrugation amplitudes is it necessary to introduce a fi nite slipping length.