Single-file mobility of water-like fluid in a generalized Frenkel-Kontorova model

Abstract

In this work we used a generalized Frenkel-Kontorova model to study the mobility of water molecules inside carbon nanotubes with small radius at low temperatures.Our simulations show that the mobility of the confined water decreases monotonically increasing the amplitude of the substrate potential at fixed commensurations. On the other hand, the mobility of the water molecules shows a non-monotonic behavior when varying the commensuration. This result indicates that the mobility of the confined fluid presents different behavior regimes depending on the amplitude of the water-nanotube interaction. In order to understand qualitatively these results, we study analytically the driven Frenkel-Kontorova model at finite temperatures.This analysis allows us to obtain the curves of the mobility versus commensurations, at fixed substrate potentials. Such curves shows the existence of three regimes of mobility behavior as a function of the commensuration ratio. Additionally, our study indicates a nontrivial and strong dependence of the mobility with a quantity that can be interpreted as an effective amplitude of the substrate potential, depending on the bare amplitude of the substrate potential, the commensuration ratio and temperature.

Diffusion behaviour of water confined in deformed carbon nanotubes

“…The superflow is not the only anomalous behavior observed in nanoconfined water. It also presents multi-phase flow, structural transitions and highly heterogeneous hydrogen bonds distribution [13][14][15].…”

Relation between boundary slip mechanisms and waterlike fluid behavior

“…Even though the no-slip boundary condition is good to describe confinement up to microchannels [24][25][26][27][28], this might not be the case for nanoconfined geometries [29][30][31][32]. Different slip condition mechanisms might occur as the relative velocity between the fluid and the wall is changed.…”

“…Confined water in microchannels presents a slip length of the order of nanometers [24][25][26][27][28] and therefore no-slip boundary conditions are not applicable. As the channel size decreases, the water mobility increases [29][30][31][32]. The slip length for nanochannels becomes of the order of micrometers, which implies that the use of no-slip boundary conditions could be problematic.…”

Water diffusion in carbon nanotubes: interplay between confinement, surface deformation and temperature

“…Thus, for the diffusion of confined water inside carbon nanotubes the important variables arebut probably not limited to -the nanotube diameter, degree of deformation (as measured by the eccentricity), chirality, and temperature. 33 The fluid-surface mismatch can be affected by nanotube deformation and chirality. [34][35][36] In particular the chirality impacts the water dipole orientation due to a difference in the partial load distribution at the ends of the tubes.…”