PRESSURE TENSOR FOR INHOMOGENEOUS FLUIDS

We develop a simple, efficient, and general statistical mechanical tec hnique for calculating the pressure tenser of an atomic fluid. The met hod is applied to the case of planar Poiseuille flow through a narrow slit pore, and the results indicate that our technique is accurate and relatively efficient. A second method to calculate shear stress is de rived from the momentum continuity equation. This mesoscopic method ag ain is seen to be accurate with low statistical uncertainty. Using bot h approaches, the viscosity is calculated as a function of position ac ross the pore, and is seen to oscillate because of a wall-induced loca l structure in the fluid. We discuss these methods in relation to the well-known ambiguity of the pressure tensor.