Molecular Dynamics Simulations of the Effect of Interaction Potential and Lattice Structure on the Slippage in a Couette Flow

Molecular dynamics (MD) simulations are used to quantify the interaction forces between molecules, which is critical to nano-channel fluid flows. The method of MD solves Newton’s equations of motion for a molecular system, which results in trajectories for all atoms in the system. From these atom trajectories, a variety of properties can be calculated. The aim of computer simulations of molecular systems is to compute macroscopic behavior from microscopic interactions. In this study, the two-dimensional model of liquid argon confined in a couette flow inside nanochannel walls is investigated. The liquid molecules are considered of different types for modeling the potential function. Three types of interatomic potentials are Lennard-Jones 12-6 potential, Lennard-Jones 9-6 potential and Lennard-Jones smooth potential. Also, the influence of change in lattice structure is investigated. The slip boundary condition is one of the marked differences between the macro- and micro or nano-scale flows. Fluid-solid interaction strength is one of the key parameters that have effect on the magnitude of slip length. The purpose of this paper is to compare simple and efficient interaction potentials for liquid molecules and assess their influence on the slip boundary and velocity profile by MD simulations. Obtained results show that. Results show that the Lennard-Jones 12-6 predicts the slippage higher than the others but its estimation for strong wall-fluid interaction is symmetric for opposite wall velocities . Also, sq2 lattice structure is the best one for hydrodynamic analysis and its results is very close to FCC lattice in 3D simulations. So by using this structure, the computational cost is reduced for 2D instead of 3D cases.

کلیدواژه ها:

Molecular dynamics ، nano-channel ، slip boundary ، Lennard-Jones