Molecular Dynamics Investigation of Pressure-DrivenWater Transport in Kaolinite NanoporesOA

This study investigates the microscopic mechanisms governing water transport in kaolinite-rich nanoporous media,a topic of considerable importance for shale gas recovery,seepage in fine-grained soils,and the migration of contaminants in low-permeability geological formations.To this end,molecular dynamics(MD)simulations are performed on slit-shaped kaolinite nanopores with different degrees of surface wettability in order to elucidate the influence of solid-liquid interactions on the structure and dynamics of confined water.The analysis focuses on the spatial arrangement,molecular orientation,and transport characteristics of water within the nanopores.The simulations show that confinement gives rise to pronounced layering of water molecules adjacent to the solid walls,with the interfacial layers exhibiting a high degree of structural ordering and preferential molecular orientation.Increasing surface wettability enhances the stability of the hydrogen-bond network,thereby reducing molecular mobility,whereas more hydrophobic surfaces weaken intermolecular interactions and promote interfacial slip.Under pressure-driven conditions,the confined liquid exhibits a Poiseuille-like velocity profile modified by slip at the solid boundaries.The mean flow velocity increases linearly with the applied pressure gradient,while fitting the numerical data to Darcy’s law suggests the existence of a threshold hydraulic gradient for the onset of flow.Overall,the study provides molecular-level insight into the relationship between pore surface properties and fluid transport,contributing to a better understanding of seepage phenomena in low-permeability porous materials and offering guidance for improving continuum-scale flow models.