Thermal, caloric and transport properties of the Lennard–Jones truncated and shifted fluid in the adsorbed layers at dispersive solid walls

Abstract

Fluid properties change when the fluid is adsorbed at a wall. The effect of the adsorption on the fluid properties was studied here by molecular simulation. There is much previous work in this field on fluids in nanochannels that are so small that the adsorbed layers on both walls interfere. In this work, the channel width was so large that the adsorbed layers did not interfere, such that information on the adsorbed layer on single walls was obtained and average values of thermodynamic properties of the fluid in that layer were determined. The studied fluid properties are: pressure p, density ρ, internal energy u, enthalpy h, isobaric heat capacity , thermal expansion coefficient , thermal conductivity λ, shear viscosity η and self-diffusion coefficient D. For the study, non-equilibrium molecular dynamics simulations were carried out. The fluid and the solid were modelled with the Lennard–Jones potential truncated and shifted at . The overall density of the fluid was . The overall temperature and the solid–fluid interaction were varied. The corresponding bulk states are liquid or supercritical. The results for the fluid properties in the adsorbed layer were compared to the corresponding bulk values and the deviations are generally below .