Effect of wall roughness on fluid transport resistance in nanopores

Abstract

Using non-equilibrium molecular dynamics simulations, we investigate the effect of wall roughness on the transport resistance of water molecules inside modified carbon nanotubes. The effective shear stress, which characterizes the strong interaction between liquid molecules and solid wall, is a quantity that dominates the nanofluidic transport resistance. Both the effective shear stress and nominal viscosity arise with the increase of the amplitude or the decrease of the wavelength of roughness. The effect of roughness is also relatively more prominent in smaller nanotubes. The molecular mechanism is elucidated through the study of the radial density profile, hydrogen bonding, and velocity field of the confined water molecules.

Channel morphology effect on water transport through graphene bilayers

“…8(a)), the water molecules move uniformly along the positive x -direction though some of them have velocity components along the channel thickness ( y ) direction. The non-zero velocity along the y -direction is consistent with the observation of the non-zero radial velocity in previous works which investigate the water transport through carbon nanotubes3031. Such non-zero velocity may be caused by the thermal vibration of the water molecules and their strong interaction with the confining GE layers.…”

“…The temperature is calculated with the center-of-mass velocity subtracted. Such thermostat coupling strategy was adopted in many previous studies concerning the transport behaviors of water molecules in carbon nanotubes13031 and GE nanosheets1434. It has been demonstrated that a direct coupling of the fluid confined in a nanochannel with a thermostat might perturb the dynamic behaviors of the fluid, and instead the coupling of the confining walls of the fluid with the thermostat to control the temperature and to dissipate the energy imposed by the external pressure would be better and also closer to practical experimental set-ups45.…”

Wettability of water droplet on misoriented graphene bilayer sructure: A molecular dynamics study

“…23 Similar with variations observed in density profiles above, near the graphene surface, there is a sudden drop in all plots, and in the middle of the water configuration, n Hbond is close to that in bulk water also showing good agreement with previous simulation reports (=3. a weakened network structure of water molecules near the graphene surface.…”

“…The cut-off radius of 1.0 nm was chosen for all L-J interactions to calculate the short-range van der Waals forces, and the particle-particle particle-mesh (PPPM) with a root mean of 0.0001 was used to handle the long range Coulomb interactions between oxygen and hydrogen atoms. 20,23 A periodic boundary condition was applied to the x and y -direction. All simulations were performed by using Large-Scale Atomic/Molecular Massively Parallel Simulator(LAMMPS).…”

Enhanced permeation of single-file water molecules across a noncylindrical nanochannel

“…The study on the flow of water across nanochannels or microchannels has many applications, e.g., for understanding biological activities [1][2][3][4][5][6][7][8], for designing nanodevices or nanomachines [6,[9][10][11], and even for studying the coalescence of Pickering emulsion droplets [12]. For example, it was found that the measured water flow across nanotubes exceeded values calculated from continuum hydrodynamics models by more than three orders of magnitude and that water permeation abilities of these nanotube-based membranes were several orders of magnitude higher than those of commercial polycarbonate membranes [13].…”