title: Slip divergence of water flow in graphene nanochannels: the role of chirality.
abstract: Graphene has attracted considerable attention due to its characteristics as a 2D material and its fascinating properties, providing a potential building block for nanofabrication. In nanochannels the solid-liquid interface plays a non-negligible role in determining the fluid dynamics. Therefore, for an optimal design of nanofluidic devices, a comprehensive understanding of the slippage in a water flow confined between graphene walls is important. In nanoconfinement, experimental and computational studies have found the slip length to increase nonlinearly when the shear rate is larger than a critical value. Here, by conducting molecular dynamics simulations, we study the influence of the graphene crystallographic orientation on the slip boundary conditions inside a nanoslit channel. The flow in channels with heights of 2.0, 2.4 and 2.8 nm is driven parallel to the zig-zag and arm-chair crystallographic directions. We extract flow rates, velocity profiles, slip velocities and slip lengths. The slip velocity displays a linear relationship to the shear stress up to a critical value, which is not size dependent. Moreover, the slip length is found to be shear stress dependent above a critical shear stress value of 0.4 MPa. Furthermore, our results indicate that after this critical shear stress is reached, the flow rates are significantly influenced (up to 10%) by the particular orientation of the graphene topology.
authors.affiliation: Universidad de Concepcion, Concepcion, Chile. harveyzambrano@udec.cl.
authors.forename: Enrique
authors.initials: E
authors.lastname: Wagemann
authors.affiliation: Universidad de Concepcion, Concepcion, Chile. harveyzambrano@udec.cl.
authors.forename: Elton
authors.initials: E
authors.lastname: Oyarzua
authors.affiliation: Technical University of Denmark, Copenhagen, Denmark and Chair of Computational Science, ETH Zurich, Zurich, Switzerland.
authors.forename: Jens H
authors.initials: JH
authors.lastname: Walther
authors.affiliation: Universidad de Concepcion, Concepcion, Chile. harveyzambrano@udec.cl.
authors.forename: Harvey A
authors.identifier: http://orcid.org/0000-0003-1049-8482
authors.initials: HA
authors.lastname: Zambrano