Poiseuille flow of Lennard-Jones fluids in narrow slit pores

We present results from nonequilibrium molecular dynamics (NEMD) simulation s of simple fluids undergoing planar Poiseuille flow in a slit pore only a few molecular diameters in width. The calculations reported in this publica tion build on previous results by including the effects of attractive force s and studying the flow at narrower pore widths. Our aims are: (1) to exami ne the role of attractive forces in determining hydrodynamic properties, (2 ) to provide clearer evidence for the existence of a non-Markovian generali zation of Newtons law, (3) to examine the slip-stick boundary conditions in more detail by using a high spatial resolution of the streaming velocity p rofiles, (4) to investigate the significance of the recently proposed cross -coupling coefficient on the temperature profiles. The presence of attracti ve interactions gives rise to interesting packing effects, but otherwise, d oes not significantly alter the spatial dependence of hydrodynamic quantiti es. We find the strongest evidence to date that Newton's Law breaks down fo r very narrow pores; the shear viscosity exhibits singularities. We suggest a method to test the validity of the non-Markovian generalization of Newto n's Law. No-slip boundary conditions are found to apply, even at these micr oscopic length scales, provided one takes into account the finite size of t he wall atoms. The effects of any strain rate induced coupling to the heat flow are found to be insignificant. (C) 2000 American Institute of Physics. [S0021-9606(00)50304-3].