Abstract
A nonequilibrium molecular dynamics simulation method adaptable to liquid phase separation through a membrane was developed. This method allows to simulate a pressure-driven permeation through a membrane with the control of pressure at different values in source and permeate regions simultaneously. To control pressure, we used two fluctuating walls set at the opposite sides of the simulated unit cell. These walls were adjusted to achieve a balance of an external pressure and potential field originated from fluid particles so that the pressure difference in the simulated unit cell was kept at constant. We successfully demonstrated the validity of our simulation method by applying this method to the permeation of liquid Ar through a slit pore model. The pressure difference in the simulated cell was kept constant as expected, and the fluid particles were moved through a pore with constant speed. The velocity distribution of fluid particles along permeate direction in the pore was almost quadratic, which was consistent with the theoretical estimated velocity distribution in the pore based on Navier-Stokes equation.
