Slip coefficient in nanoscale pore flow

Area of Science:

• Fluid Dynamics
• Nanoscale Science
• Physical Chemistry

Background:

• Hydrodynamic solutions often use Maxwell's boundary conditions, incorporating an empirical slip coefficient (SC).
• Existing SC derivations typically assume half-space flow and neglect finite-size effects crucial for nanopore environments.

Purpose of the Study:

• To develop an expression for the slip coefficient (SC) applicable to fluid flow within nanoscale pores.
• To incorporate finite-size effects into SC calculations, which are dominant in nanopore flow.
• To validate the new SC expression using nonequilibrium molecular-dynamics simulations.

Main Methods:

• Developed a theoretical expression for the slip coefficient (SC) considering finite-size effects in nanopores.
• Employed nonequilibrium molecular-dynamics simulations to verify the derived SC expression.

Main Results:

• The study presents a validated SC expression for nanoscale fluid flow.
• Results indicate a strong dependence of the slip coefficient on pore width for small pores.
• The SC approaches a constant value for pore widths exceeding approximately 20 molecular diameters, deviating from Maxwell's linear scaling prediction.

Conclusions:

• The derived SC expression accurately models slip flow in nanopores, incorporating essential finite-size effects.
• Nanopore width significantly influences the slip coefficient, challenging traditional hydrodynamic theories.
• This work provides a more accurate approach for predicting fluid behavior in nanoscale confinement.