A Molecular Dynamics Study of Fluid Flows Through Slit-Like Nanochannels Using Two Different Driving Systems

The Poiseuille flow through slit-like nanochannels is investigated using the nonequilibrium molecular dynamics simulations. To drive a dense flow through the channel, we use two self-adjusting vertical plates strategy. These plates force the liquid to flow through the nanochannel under adjustable inlet and outlet boundary conditions. Comparing with the dual-control-volume grand-canonical molecular dynamics method, the current strategy provides many advantages. The current strategy does not need particle insertion and deletion, therefore, the system dynamics would not be affected at all. Moreover, the number of particles in the simulation system is fixed due to inserting the two self-adjusting vertical plates at the two ends of the nanochannel. The motion of these plates are controlled using a combination of an externally applied force and an internal force produced by the molecules in the system. Using this strategy, we study the transport of liquid argon and oxygen through a few slit-like nanochannels having different sizes. We benefit from the nonequilibrium molecular dynamics (NEMD) strategy in our simulations. To expand our study, we consider different back pressure implementations in the flow through the nanochannel. The current results are eventually compared with those derived by applying a uniform driving force method and their advantages are described.