Continuum modeling of nanoconfined fluid transport governed by intermolecular potentials

Understanding liquid flow mechanisms within nanoscale pores is crucial for diverse scientific and engineering applications. Extensive studies indicate that fluid flow in nanochannels exhibits anomalous characteristics that deviate from conventional continuum hydrodynamics. To address this, a semi-classical continuum framework was developed by intrinsically coupling microscopic intermolecular potentials with macroscopic transport equations. By solving self-consistent density-potential functions, the model accurately predicts fluid density distributions and derives an inhomogeneous viscosity field governed by the potential energy distribution. Validation against molecular dynamics simulations confirms that the model successfully reproduces near-wall density oscillations and the characteristic plug-like velocity profiles, overcoming the limitations of the conventional slip model, which fails to capture near-wall viscosity variations and the depletion area. Furthermore, based on the physical scaling law between potential energy and density, the viscosity model is generalized to accommodate both polar and non-polar fluids. Parametric studies reveal that wall thickness exceeding 0.5 nm has a negligible impact on density, while reduced apertures significantly enhance solid–fluid interactions. The proposed framework extends continuum model applications to nanoscale systems, providing a robust and rapid paradigm for bridging nanoscale mechanisms with macroscale engineering predictions.