Research On Slip Characteristic Of Micro/Nano Liquid Flow Using Optimized Multiscale Algorithm

The slippage phenomenon is common in micro/nano-electro-mechanical systems(MEMS/NEMS),which is one of the most important factors that design and apply the MEMS/NEMS devices.In this paper,the optimized atomistic-continuum hybrid method is applied to investigate the slip characteristics in micro/nanochannels flow.The main contents are summarized as follow:(i)The spatial and temporal coupling parameters and the couple scheme that the boundary condition transfers from continuum region to atomistic region are investigate the effects on the calculation accuracy of atomistic-continuum hybrid method.It is found that that overlap region height,A?C region height and time coupling param-eters need to be moderate for the reason that too large or too small parameters will decrease the accuracy of HAC calculation.Moreover,under the conditions of ensur-ing the buffer region existence,the calculation accuracy would be more higher with the increasing of the height of C?A region.The simulation results of relaxation dynam-ics method coupling scheme obtain the highest accuracy,the simulation results of least constraint method coupling scheme obtain the medium accuracy and the simulation re-sults of Maxwell buffer method coupling scheme obtain worst accuracy.In addition,the boundary model utilized to solve non-periodic boundary condition(NPBC)has been proposed.The the boundary model can provide the missing boundary force and is easy to expand multidimensional.(ii)The optimized atomistic-continuum hybrid method is applied to investigate the influences of the channel height and solid-liquid interaction parameters on slip char-acteristics in micro/nanochannels.It is found that the relative slip lengths obviously decrease and eventually drop to zero with the increase of channel height.No matter how the channel height changes,the characteristics of solid-liquid surface slip will not change.The fewer density oscillations are generated near the solid wall with the chan-nel height increasing.The solid-liquid surface will change from hydrophobic to hy-drophilic with the increase of the solid-liquid energy scales ratio.During this process,the arrangement of liquid particles adjacent to the solid particles is more organized and the probability of the liquid particles appear near the solid particles becomes bigger.When the solid and liquid particles have the same diameter,the relative slip length will reach the minimum value.No matter how the solid-liquid interaction parameters change,there is always a linear relationship between relative slip length and shear rate.Moreover,The plenty computational time has been saved by the present hybrid method compared with the full molecular dynamics simulation.