Using non-equilibrium molecular dynamics simulations, we investigate the effect of wall roughness on the transport resistance of water molecules inside modified carbon nanotubes. The effective shear stress, which characterizes the strong interaction between liquid molecules and solid wall, is a quantity that dominates the nanofluidic transport resistance. Both the effective shear stress and nominal viscosity arise with the increase of the amplitude or the decrease of the wavelength of roughness. The effect of roughness is also relatively more prominent in smaller nanotubes. The molecular mechanism is elucidated through the study of the radial density profile, hydrogen bonding, and velocity field of the confined water molecules.
The work is supported by National Natural Science Foundation of China (Contract No. 50928601), World Class University program through the National Research Foundation of Korea (R32-2008-000-20042-0), Changjiang Scholar Program from Ministry of Education of China, National Science Foundation (CMMI-0643726), and DARPA (W91CRB-11-C0112).