Boundary slip and interfacial friction properties of confined-water flow on graphene under electrowetting

The boundary slip and interfacial friction properties of confined-water flow on two parallel single-layer graphene sheets w ith a separation of 6 nm under electrow etting conditions w ere investigated by molecular dynamics simulation and boundary slip theory.For both electrow etted and uncharged graphenes,the flow velocity profiles perpendicular to the flow direction,shear stress, boundary slip velocity,slip length and interfacial friction coefficient w ere obtained w ith a graphene-w ater Couette flow model.Results show that the slip length increases abruptly w hen the shear rate is above a critical value.The critical shear rate in the electrow etted graphenes is obviously larger than that in uncharged ones.The interfacial friction coefficient betw een graphene and w ater decreases w ith the shear rate and is increased by electrow etting the graphenes.The w ater viscosity is independent of the shear rate in both eletrow etted and uncharged graphenes.