Contact Angle of Sessile Drops in Lennard-Jones Systems

Abstract

Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.

Droplets sliding over shearing surfaces studied by molecular dynamics

“…The time averages shown in Figure 5 were collected over a subsequent period t à ¼ 460. As has been observed in earlier studies, 18 layering occurs near the substrate, most visible for the drops with the smaller contact angles. When fitting a circular arc to the interface to determine the static contact angle, the part of the interface near the substrate is discarded.…”

“…[12][13][14] Limiting this brief literature review to topics most relevant to the current paper (MD of LJ fluids, drops on substrates, and pore-scale modeling in oil recovery), there is significant activity over the past 10 years. Phase behavior of LJ fluids, 15 their transport coefficients, 16 and their interaction with solid substrates [17][18][19] have been reported in a variety of ways and situations, including deformation of drops on surfaces due to force fields. 20 Interaction between liquids and substrates is also of key importance in the formation and rupture of liquid bridges.…”

Snowflake Melting Simulation Using Smoothed Particle Hydrodynamics

“…This effect is more difficult to connect directly to macroscale physics, but it has the great advantage of avoiding the instability involved in estimating surface curvature. We were further encouraged to favor this approach by the fact that in molecular dynamics, realistic surface behavior can be simulated at the molecular scale from simple pairwise forces using the Lennard‐Jones potential (Becker et al, ).…”

Effects of Lubrication on the Friction in Nanometric Machining Processes: A Molecular Dynamics Approach

“…E.g. in [15], the wetting of solids was systematically investigated using LJTS models for representing the liquid and the gas, as well as the solid. The simple LJTS potential is, however, not suited for appropriately describing details of the solid's behavior like dislocations.…”

“…• according to Becker et al [15]. The same value is chosen for the indenter-fluid interaction: ε IF = 0.5 ε.…”