MOLECULAR DYNAMICS STUDY OF HEAT TRANSFER IN TWO-PHASE FLOWS THROUGH A NANOCHANNEL

Two-phase flows through micro- and nanochannels have attracted a great deal of attention because of their immense applicability to many advanced fields such as micro/nano-electro-mechanical systems (MEMS/NEMS), electronic cooling, bioengineering, etc. In this work, a molecular dynamics simulation method is developed to study the condensation process of superheated argon vapor force driven flow through a nanochannel combining fluid flow and heat transfer. A simple and effective particle insertion method is proposed to model phase change of argon based on nonperiodic boundary conditions in the simulation domain. Starting from a crystalline solid wall of channel, the condensation process evolves from a transient unsteady state where we study the influence of different wall temperatures and fluid-wall interactions on interfacial and heat transport properties of two phase flows. Subsequently, we analyzed transient temperature, density, and velocity fields across the channel and their dependency on varying wall temperature and fluid wall interaction, after a dynamic equilibrium is achieved in phase transition. Quasi-steady nonequilibrium temperature profile, heat flux, and interfacial thermal resistance were analyzed. The results demonstrate that the molecular dynamics method, with the proposed particle insertion method, effectively solves unsteady nonequilibrium two-phase flows at nanoscale resolutions whose interphase between liquid and vapor phase is typically of the order of a few molecular diameters.