Abstract
Water molecules sheared by two parallel graphene sheets are simulated using molecular dynamics simulations. The shear rate of water flow increases with increasing pull velocity of graphene sheets until the limiting shear stress of graphene sheets is reached. Compared with the uncharged graphene sheets, the introduction of the charge can enhance the interaction strength between the carbon atoms and the water molecules, which results in the increase of the limiting shear rate and the decrease of the slip length. For the graphene sheets with different charges, the boundary slip decreases with increasing charge on the carbon atoms. Meanwhile, compared with the uncharged graphene sheets, the water molecules dragged by the graphene sheets with 0.20 e per carbon atom exhibit an opposite trend in the velocity profile at the boundary. The simulation results also reveal slight discrepancy in the influence of the electric property (negative and positive charges) on the water flow confined between charged graphene sheets.
Acknowledgements
The supports of the National Natural Science Foundation of China (11072051, 90715037, 10902021, 91015003, 10728205, 10721062, 11102074), NSFC-JST (51021140004), the 111 Project (No. B08014), the National Key Basic Research Special Foundation of China (2010CB832704), the Program for Changjiang Scholars and Innovative Research Team in University of China (PCSIRT) and Natural Science Foundation of Jiangsu Province (BK201163) are gratefully acknowledged.