Effects of interface wettability and fluid property on poiseuille flows in nanochannels

Abstract

Due to the size effect, the solid–fluid interface properties have great influences on the flow characteristics of nanofluid in channels, showing significant differences compared with macro fluids. Therefore, the fabrication and applications of micro/nano-fluidic chips require deep insights into nanofluidics and micro- and nanoscale fluid mechanics. In spite of the numerical theoretical researches on relationship of interface wettability and slip length, the studies on quantitative relationship and the fluid property itself have been rarely discussed. Here, by using molecular dynamics (MD) simulations, the effects of interface wettability and fluid properties on nanoflow characteristics and solid–liquid interface slip are demonstrated through modulating the parameters of Lennard-Jones (L-J) potentials for describing the interfacial wettability of Poiseuille flow. It is observed that the low energy parameter and large distance parameter of L-J potential interactions between solid and liquid improve the boundary slip on the interface and enhance the velocity in the channel. Similar results can be found as the potential function parameters between liquid atoms vary, the density and velocity curves can dramatically deviate from normal distribution, while the slip phenomenon behaves nearly no difference, showing almost the same velocity slip. Furthermore, the dependence of slip length on potential function parameters is predicted and the quantitative relationship has been established. It can be concluded that the slip length on the interface exponentially changes with the potential parameters of wall-fluid, which could be useful for the design and simulation of future micro/nano-fluidic systems.