Enhanced flow of core-softened fluids through nanotubes

TL;DR

This study uses molecular dynamics simulations to explore how core-softened fluids flow through nanotubes, revealing anomalous flux behaviors linked to flow transitions and layered structures, similar to water in nanotubes.

Contribution

It uncovers novel flow transitions and layered structures of core-softened fluids in nanotubes, advancing understanding of nano-fluidic transport mechanisms.

Findings

Mass flux increases anomalously at small radii.

Flow transitions from single-file to ordered-like fluid.

Formation of double-layer flow at larger radii.

Abstract

We investigate through non-equilibrium molecular dynamic simulations the flow of core-softened fluids inside nanotubes. Our results reveal a anomalous increase of the overall mass flux for nanotubes with sufficiently smaller radii. This is explained in terms of a transition from a single-file type of flow to the movement of an ordered-like fluid as the nanotube radius increases. The occurrence of a global minimum in the mass flux at this transition reflects the competition between the two characteristics length scales of the core-softened potential. Moreover, by increasing further the radius, another substantial change in the flow behavior, which becomes more evident at low temperatures, leads to a local minimum in the overall mass flux. Microscopically, this second transition results from the formation of a double-layer of flowing particles in the confined nanotube space. These special nano-fluidic features of core-softened particles closely resemble the enhanced flow behavior observed for liquid water inside carbon nanotubes.