Flow Behaviors Of Fullerene Nanofluids In Graphene Nanochannels

With the rapid development of micro/nano technology,material science and technology,the mechanism of fluid flows confined in nanochannels has attracted great attention for the future application of the nanofluid devices.Using classical molecular dynamics(MD)simulation,this work focuses on the flow behaviors of fullerene nanofluids and the transport properties of fullerene molecules in graphene nanochannels.The research will provide a theoretical basis for understanding the flow behaviors of nanofluids in graphene nanochannels and designing graphene-nanofluid devices.The Couette flow and Poiseuille flow properties of fullerene nanofluids in graphene nanochannels are firstly investigated,exploring the effects of shear velocity,driving force,fullerene volume fraction,electric field intensity and nanochannel width on the boundary slip.The results show that the boundary slip velocity increase with the increase of the fullerene volume fraction.It is also found that the positive slippage is observed at the boundary when the electric field intensity is relatively weak,and as the electric field intensity increases,the boundary slip velocity decreases.However,the negative slippage emerges when the electric field intensity reaches the critical value,and as the electric field intensity further increases,the boundary slip velocity decreases firstly and increases later.In addition,in the Couette flow,the boundary slip velocity increases abruptly when the shear rate exceeds a critical threshold,and this threshold increases as the electric field intensity increases.Meanwhile,the boundary slip velocity decreases as the nanochannel width increases.In the Poiseuille flow,the velocity of nanofluids increases with the increase of the external driving force and the nanochannel width,leading to the increase of the boundary slip velocity.Basing on the Couette flow model composed of fullerene nanofluids and graphene,the effects of shear velocity,fullerene volume fraction and electric field intensity on the viscosity of nanofluids are also explored.The results indicate that the viscosity of the fullerene nanofluids is not sensitive to the shear strain rate,but increase with the increase of the fullerene volume fraction.In addition,when the electric field intensity is relatively weak,and as the electric field intensity increases,the viscosity increases.However,when the electric field intensity reaches the critical value,and as the electric field intensity further increases,the viscosity of the nanofluids decreases firstly and increases later.Basing on the Poiseuille flow model composed of fullerene nanofluids and graphene,the motion behavior and distribution of fullerene molecules are investigated.The results show that the phenomenon of fullerene molecules cluster is more evident with the small driving force and nanochannel width,i.e.,the fullerene molecules cluster can be weakened by the increase of the driving force and the nanochannel width,resulting to the increase in the number of molecule clusters.By contrast,the increase in fullerene volume fraction can facilitate fullerene molecules forming cluster.Meanwhile,the fullerene molecules cluster can be weakened by the increase of the electric field intensity when the electric field intensity is relatively weak,and the fullerene molecules tend to flow toward the walls,causing the fullerene molecules to flow near the walls of graphene.However,the fullerene molecules will flow again near the center of the channel with the enhancement of the electric field strength when the electric field intensity is relatively strong.In addition,it is also found that the number of fullerene molecules has significant influence on the total rotational kinetic energy of the fullerene molecules in the flow system,while the driving force and electric field strength do not.