Confinement effects on liquid-flow characteristics in carbon nanotubes

Area of Science:

• Nanotechnology
• Fluid Dynamics
• Computational Physics

Background:

• Understanding liquid flow in carbon nanotubes (CNTs) is crucial for nanoscale transport phenomena.
• Molecular dynamics simulations offer a powerful tool to investigate fluid behavior at the nanoscale.

Purpose of the Study:

• To elucidate liquid flow dynamics through armchair carbon nanotubes (CNTs) using molecular dynamics simulations.
• To analyze the impact of CNT diameter on fluid velocity profiles and slip lengths.

Main Methods:

• Molecular dynamics simulations were employed to model nonpolar argon atom flow.
• A finite difference-based velocity fitting method was developed to analyze radial density distributions.
• Velocity profiles and slip lengths were calculated for varying CNT diameters.

Main Results:

• Slip length and flow rate enhancement exhibit three-step transitional profiles as CNT diameter increases (D≤2.3 nm).
• The first transition shows a stepwise increase in slip length and flow rate, corresponding to a structural change from single-file to single-ring molecular clusters.
• Subsequent transitions reveal drops in slip length and flow rate as inner layers form within the ring structure.

Conclusions:

• CNT diameter significantly influences liquid flow dynamics and slip length.
• The observed transitional profiles are directly linked to the evolution of fluid molecular structures within the CNT.
• This study provides fundamental insights into nanoscale fluid transport within carbon nanotubes.