Liquid Transport Through Nanoscale Porous Media with Strong Wettability

J Zhang and HQ Song and WY Zhu and JL Wang, TRANSPORT IN POROUS MEDIA, 140, 697-711 (2021).

DOI: 10.1007/s11242-020-01519-5

It is important to investigate interfacial effects on liquid transport characteristics through nanopores with strong wettability due to potential applications in several fields. The structural and transport properties of wetted liquid argon through nanochannels were investigated via molecular dynamics (MD) simulations. A mathematical model for liquid flow in nanoporous media was established based on the constant negative slip length by combining MD simulations with fractal theory for complex media. The results show that the strong liquid-solid attraction allows the liquid to be adsorbed onto the solid walls. In addition, compared with the bulk diffusion coefficient in the center of the nanochannel, the coefficient parallel to the interface near the solid walls is largely reduced, indicating the liquid molecules are strongly bound to the solid walls. Furthermore, negative slip can exist in the vicinity of solid walls with strong wettabilities. The variations in negative slip length with the external driving force can be characterized by two regimes. In steady negative slip regime, the negative slip length remains constant. As the driving force continues to increase, the transition negative slip regime exists, where the negative slip length decreases linearly with the driving force until the slip length becomes zero. The presence of a negative slip length reduces the liquid flow rate compared with no slip or a positive slip length due to the reduced effective cross section for fluid transport. Moreover, the increased fractal dimensions about the capillary radius result in an enhanced liquid flow rate, while that about the tortuosity reduces the liquid flow rate.

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