Pressure-dependent flow enhancement in carbon nanotubes

Area of Science:

• Fluid dynamics
• Nanotechnology
• Materials science

Background:

• Standard Navier-Stokes (NS) equations with non-slip boundary conditions fail to accurately describe pressure-driven nanoconfined fluid flow.
• Experimentally measured flow rates in nanoconfined systems significantly exceed predictions from macroscopic continuum models.
• Previous studies report vast discrepancies (over five orders of magnitude) in flow enhancement factors, highlighting a fundamental inconsistency.

Purpose of the Study:

• To investigate the anomalous flow enhancement phenomenon in nanoconfined fluids within a 2 nm carbon nanotube.
• To elucidate the underlying mechanisms responsible for the observed non-monotonic correlation between flow enhancement and fluid pressure.
• To propose a molecular-level explanation for the inconsistencies in nanoconfined fluid flow behavior.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model fluid behavior within a carbon nanotube.
• Analyzed the correlation between fluid pressure and flow enhancement factors.
• Investigated molecular interactions, including hydrogen bonding and water orientation, under varying pressures.

Main Results:

• Observed an anomalous non-monotonic correlation between flow enhancement and fluid pressure in a 2 nm carbon nanotube.
• Identified fluid phase transitions induced by pressure as the primary cause of inconsistent flow behaviors.
• Revealed that complex hydrogen-bonding interactions and regulated water orientations govern the nanomechanical mechanisms.

Conclusions:

• The inconsistency in nanoconfined fluid flow enhancement can be explained by pressure-induced phase transitions and associated changes in molecular structure.
• Molecular dynamics simulations provide insights into the nanomechanical mechanisms driving these phenomena.
• Considering pressure-dependent molecular structures is crucial for accurately modeling nanoconfined fluid dynamics.