Nonpolar and polar fluid flow through flat nanochannels with amorphous and crystalline walls

•Polar and nonpolar fluid flow in flat nanochannels is studied via MD simulations.•The molecular polarity and structure of the boundary walls is shown to have strong influences fluid flow.•In nanochannels with amorphous walls, nonpolar fluids depict a larger flow velocity.•On the other hand, polar fluids flow faster in crystalline nanochannels.

The flow of nonpolar and polar fluids through flat nanochannels with amorphous and crystalline boundary walls is investigated by means of molecular dynamics (MD) simulations. It is shown that the fluid polarity and structure of the boundary walls have very strong influences on both the average fluid flow rate and the shape of the fluid velocity profiles. For channels with amorphous boundary walls, the nonpolar fluid flow appears to be faster than the flow of the polar fluid, whereas for channels with crystalline boundary walls, one has the reversed trend. This feature is discussed under the light of the larger self-diffusivity of bulk polar fluids, contrasting with their smaller slip velocities near crystalline walls.