Surface effects on nanoscale Poiseuille flows under large driving force

Area of Science:

• Physics, specifically fluid dynamics and surface science.
• Materials science, focusing on nanoscale phenomena.
• Computational chemistry and condensed matter physics.

Background:

• Understanding fluid behavior at the nanoscale is crucial for microfluidic devices and material design.
• Poiseuille flow, the flow of a fluid in a tube, is a fundamental concept, but nanoscale effects introduce complexities.
• Fluid-wall interactions play a significant role in determining flow properties at reduced dimensions.

Purpose of the Study:

• To investigate the influence of fluid-wall interactions on fluid flux in nanoscale Poiseuille flows.
• To compare the behavior of liquid argon (Ar) and helium (He) under varying fluid-wall interaction strengths.
• To analyze the impact of large external driving forces on these nanoscale fluid systems.

Main Methods:

• Molecular dynamics simulations were employed to model the fluid behavior.
• The study focused on liquid Ar and He confined between two parallel planar walls.
• Mass fluxes were measured by systematically varying the effective surface effects and fluid-wall binding energy.

Main Results:

• Liquid argon exhibited a bimodal behavior in its mass flux as the effective surface effect changed.
• This bimodal flux behavior observed for argon was not present in the simulations for helium.
• Helium's flux was independent of fluid-wall binding energy at weak interactions but decreased monotonically with increasing binding energy at strong interactions.

Conclusions:

• Fluid-wall interactions have a differential effect on the flux of different nanoscale fluids like Ar and He.
• The observed bimodal behavior in Ar suggests complex surface-induced ordering or layering effects.
• Helium's distinct response highlights the importance of fluid properties (e.g., atomic size, interaction potential) in nanoscale confinement.