Non-equilibrium molecular dynamics method is applied to determine the slip length of fluid in the vicinity of the boundaries in Poiseuille flow in a nano-channel with and without nanoscale roughness, in which pressure is imposed to the fluid. Our simulations reveal the boundary roughness effect on the interfacial interaction between the fluid and boundary, which will result in the change of fluid velocity, and this phenomenon is more distinct with boundary roughness height. Bonding energy between solid boundary and fluid atoms is also calculated to make a comparison with that of pure fluid. Roughness changes with highness and its shape, so the key factors controlling fluid flow are presented. The simulation results show that there's a relationship between the bonding energy at fluid - solid boundary interface and the fluid kinetic properties. In the case of rough surfaces, the bonding strength between liquid and solid atoms has a strong signature in the fluid velocity close to the boundary. In addition, temperature effect is also considered in our simulations, and we find that temperature also affect the hydrodynamic properties of fluid flowing in nano-channel significantly.
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