Molecular dynamics simulation of heterogeneous nucleation on nanotubes

Vapour-to-liquid nucleation of argon on silicon nanotubes is studied by means of classical molecular dynamics. The aim of this simulation study is primarily to address the question of whether condensation is faster on the inner surface or on the outer surface of the nanotube. A constant particle number, volume and temperature ensemble was used for the molecular dynamics simulation with the system having different supersaturation ratios, tube lengths, and pore sizes. For a larger pore, the growth rate of droplets was higher on the inner surface, whereas for a smaller pore, a crossover occurred depending on the supersaturation ratio. Pore plugging was strongly affected by the tube diameter, where initial clogging was critical in expediting the filling process inside the tube. Furthermore, in order to examine how the pore existence affects the surrounding vapour, lids on both ends of the tube were placed. In terms of growth, the open-ended tube was typically the slowest, whereas the fully filled cylinder generally gave rise to the highest growth rate.