EXPLORATION OF NANOSCALE FEATURES OF THIN LIQUID FILMS ON SOLID SURFACES USING MOLECULAR DYNAMICS SIMULATIONS

摘要

Thin liquid films on solid surfaces are seen in a variety of systems including bubble growth during nucleate boiling and microgroove heat pipe evaporators and condensers. The small thickness of such films leads to difficult experimental observation of phenomena within various regions of the film: the wall-affected region, the bulk liquid, and the liquid-vapor interfacial region. A novel hybrid simulation methodology is used that combines a deterministic molecular dynamics simulation of the liquid regions with a stochastic treatment of the far-field vapor region boundary. In this simulation scheme, the imposed far-field pressure is iterated as the simulation is advanced in time until the mass in the system stabilizes at the specified temperature. This establishes the equilibrium saturation vapor pressure for the specified temperature as dictated by the intermolecular force interaction models for the fluid and molecules near the solid surface. Simulation results are presented for an argon liquid film on a metallic surface. The simulated surface tension values compare favorably with those from ASHRAE tables, although the simulated saturation density and pressure values behave as though the system is at a slightly higher temperature. The method presented here is a viable tool for simulating thin films on solid surfaces for systems operating far from the critical point.