Effect of secondary regular microstructure on the micro-flows in nano-channel with low surface energy

In order to investigate the property of nano-Poiseuille flow using molecular dynamics simulation, while the channel has secondary regular microstructure and low surface energy. In the simulation, statistical ensemble is set as NVE, LJ/126 model as the potential energy function and rigid-atom model is used to describe the wall and the time/rescale thermostat to keep the temperature of fluid constant. Meanwhile, the potential energy parameter between solid and liquid atoms is adjusted to realize the wall of low surface energy. The results show that when the channel wall has microstructure, the vertical density profiles of fluid appeared two oscillation regions near the wall, namely significant weak oscillation within the microstructure (called second oscillation) and strong oscillation in the channel. With the increase of rectangle microstructure period (T), the oscillation degree of density profile within the secondary microstructure increase, while the oscillation in the channel is decrease. The increase of depth (H) of the rectangle microstructure result in a secondary oscillation amplitude decreases and the starting point of density profile move away the center of channel. The period and depth of the secondary microstructure also has a significant influence on the flow. As T and H increase, the average flux of channel also increase, which suggests that the channels present better drag reduction effect.