Pressure-driven molecular dynamics simulations of water transport through a hydrophilic nanochannel

Transport of fluids inside porous materials is relevant to many fields of application. Non-equilibrium molecular dynamics simulation is a powerful technique to explore fluid transport through porous media at the molecular scale. In this work, we compared two commonly used methods for studying pressure-driven transport. The first method was based on the application of an external force field on each fluid particle. The second method made use of two movable walls, acting as pistons, so as to generate transport. These two methods were used to study water transport inside a cylindrical hydrophilic silica nanopore. Several pressure differences were considered from 20 bar to 1000 bar. The results were compared to the theoretical Poiseuille fluid flow. No significant difference was found between the two methods. However, a substantial water flow enhancement was observed compared with the theoretical flow. Both the structural and dynamical properties of water remained unaffected by the applied pressure difference.