Influence of wall–fluid interaction on the relationship between mass transfer and nanopore width

In this study, the influence mechanisms of the nanopore width on mass transfer characteristics for methane nanofluidic are explored by non-equilibrium multiscale molecular dynamics simulation systematically. The numerical results indicate that the diffusion coefficient increases with the increase in the nanopore width via the quasi-parabolic paths. In the middle of nanopore, the local diffusion coefficients increase with the increase in the wall–fluid interaction strength factor; however, the change of local diffusion coefficient is reversed in the fluid domain near the nanopore wall. Moreover, the results show that the residual decreases with the increase in the degree polynomial of 1h. According to these fitting functions, it can be found that the diffusion coefficient approaches 80% of that of bulk system when the nanopore width increases to 14 times the diameter of methane molecule. Furthermore, the velocity autocorrelation functions and the diffusion coefficients (x, y, and z direction) demonstrate that the methane nanofluid shows anisotropy characteristics. In addition, the mean interaction force potential and slip velocity also indicate that the wall–fluid interaction strength factor and the nanopore width significantly affect the mass transfer characteristics of nanofluidic. The numerical results would be helpful to comprehend the mass transfer characteristics of nanofluidics. It should be considered in the optimal design of nano-devices.