Examination of Couette Flow with a Pressure Gradient and Heat Conduction Using Molecular Dynamics Simulation

Abstract

Featured Application This study aims to fill a knowledge gap in rarefied gas flows, addressing the complexities related to wall temperatures and pressure differentials in the simulation of gas-solid interactions in nanoscale and microscale geometries. The findings are relevant to diverse microfluidic applications, encompassing devices such as micro-nano electronic devices. Simulations were carried out in non-dimensional form so that the results can be extended to all noble gases.Abstract As computer capabilities improve, Molecular Dynamics simulations are becoming more important for solving various flow problems. In this study, Couette and Poiseuille flows at different wall temperatures were investigated using a hard-sphere Molecular Dynamics simulation approach. Although a low spacing ratio was used in the simulations, the results are valid for rarefied gas flows when proper scaling based on the Knudsen number was used because only binary collisions with a hard-sphere model were considered. The main focus of this study was the examination of the effects of various wall speeds, pressure gradients, and wall temperatures. A pressure gradient was generated by developing a modified selective periodicity condition in the flow direction. With the combined effect of the pressure gradient and the wall velocities, subsonic, transonic, and supersonic speeds in nanochannels were examined. With the combination of different parameters, 1260 simulation cases were conducted. The results showed that there are temperature and velocity slips that are dependent on not only the temperature and velocity values but also on the magnitudes of a pressure gradient. The pressure gradient also caused nonlinearities in temperature and velocity profiles.