Effect of wall potentials on the vapor and liquid flows in narrow channels

Abstract

The flow of dense gases and liquids in narrow pores is theoretically described by the microhydrodynamic approach, which can be used to study the effect of wall potentials on the parameters of molecular flows. Calculations are made on the basis of Navier-Stokes equations in which the transport coefficients and the equation of state for a component are calculated using the simplest molecular model such as the lattice-gas model, which takes into account the own volume of molecules and their interaction. To use this approach, it is necessary to know only the interaction potentials between molecules themselves and between molecules and pore walls. The transport coefficients and the equation of state depend on the local values of vapor and liquid number densities and temperature. The approach can be used to study the processes in channels at a nanometer level. Dynamic flows of a monatomic gas (argon) in slit-like pores of different widths at a given pressure difference across the pore are studied. It is shown that the strong attraction between low-density argon atoms and the walls of the pore is accompanied by a highly anisotropic flow. The decrease in the attractive force between molecules and pore walls gives rise to a vapor or liquid slip flow at the walls.