Molecular-dynamics simulation of evaporation processes of fluid bridges confined in slitlike pores

Abstract

A simple fluid, described by point-like particles interacting via the Lennard-Jones potential, is considered under confinement in a slit geometry between two walls at distance Lz apart for densities inside the vapor-liquid coexistence curve. Equilibrium then requires the coexistence of a liquid "bridge" between the two walls, and vapor in the remaining pore volume. We study this equilibrium for several choices of the wall-fluid interaction (corresponding to the full range from complete wetting to complete drying, for a macroscopically thick film), and consider also the kinetics of state changes in such a system. In particular, we study how this equilibrium is established by diffusion processes, when a liquid is inserted into an initially empty capillary (partial or complete evaporation into vacuum), or when the volume available for the vapor phase increases. We compare the diffusion constants describing the rates of these processes in such inhomogeneous systems to the diffusion constants in the corresponding bulk liquid and vapor phases.

Molecular dynamics study of the processes in the vicinity of the n-dodecane vapour/liquid interface

“…Based on molecular dynamics simulations, interfacial properties of n-alkane liquid-vapour interfaces had also been studied [30][31][32][33][34][35][36].…”

Contact Angle Dependence on the Fluid−Wall Dispersive Energy

“…The arithmetic mean density ρ vl = (ρ +ρ )/2 was applied to define the position of the phase boundary, where ρ and ρ are the saturated bulk densities of liquid and vapor which are known for the LJTS fluid from previous work 20 . In the immediate vicinity of the wall, the fluid is affected by short-range ordering effects 8,15,32 . The influence of this phenomenon was minimized by taking density averages over a bin size of about 1 σ , cf.…”

“…Since adsorption in nanopores can be studied on the basis of effective pair potentials 3,[5][6][7][8][9] , it is obversely possible to fit model parameters to adsorption isotherms 10 . The present study follows the line of research, suggested by WERDER et al 11 , of adjusting unlike parameters to contact angle measurements.…”

Evaporation of polar and nonpolar liquids from silica gels and fumed silica

“…The confined space effects are very strong in narrow pores (nanopores at R p < 1 nm and narrow mesopores at R p < 2 nm) [8,[18][19][20][42][43][44]. Therefore, these effects can be ignored for silica gels Si-60 and Si-100 and fumed silica A-300.…”

“…The properties of liquids (surface tension, boiling and critical temperatures, density, diffusivity, mobility, etc.) in strongly confined space can significantly differ from those of bulk liquids [8,19,20]. These effects become stronger in narrower pores depending on the pore wall nature and shape.…”