Investigation of thermocapillary migration of nanodroplets using molecular dynamics

Molecular dynamics is used to investigate the thermocapillary motion of a water nanodroplet suspended in benzene subjected to a constant temperature gradient. This framework lets us identify the average behavior of the fluid particles by revealing their mean evolution. We connect such statistics to the behavior of the temporally evolving nanodroplet, thereby providing a microphysical foundation to existing macroscopic models that rely on the assumption of continuum. It is shown that, despite the significant Brownian effects, the droplet exhibits the macrophysical expected behavior, i.e., it migrates toward the direction of the imposed temperature gradient. Thermophoretic effects are negligible and the functional relationships involved in such a process well resemble those of available analytical results. Additionally, we provide molecular dynamics calculations of the viscosity, thermal conductivity, and interfacial tension of benzene [using the Optimized Potentials for Liquid Simulations—All Atom (OPLSAA) molecular model] and water using the Transferable Intermolecular Potential with 4 Points (TIP4P) model at different temperatures and pressures. These findings will serve as a good reference for future simulations of similar molecular models.