Molecular Dynamics Simulation Of Wall Slip In Gas Flow

The mechanism of wall slip is a fundamental problem in the study of rarefied gas flow,which has closely ties with the motion behavior of gas molecular at the surface of wall。In this paper,molecular dynamics simulation method was adopted to investigate the mechanism of wall slip and the interaction between gas and wall。A proper model for two-dimensional molecular dynamics simulation(2DMD) was established to acquire the distribution of velocity and number density in two-dimensional Couette and Poiseuille gas flow which are under microscale 。Comparisons and verifications were carried out between the result of simulation and analytical solution under slip boundary condition,the result demonstrates that the 2DMD method can simulate the wall slip accurately。Through adjusting the simulation parameters, we can get the characters of Couette gas flow under different conditions。The result shows that wall slip is linked with the number density in the area near the wall,the phenomenon of wall slip is becoming to be obvious with the drop of number density near the wall。At the same time,the changes of potential factor and temperature of wall can impact the number density near the wall,thus,the wall slip became distinctly different。Against the problem of the interaction between gas molecular and wall,computations is implemented which is based on different wall model for molecular dynamics simulation。The trajectories and velocity of molecular was recorded during the simulation,through the analysis of the change of position and momentum with time,there typical reflect behaviors of gas molecular was found:direct reflect,reflect after several impacts and reflect after trapped。The tangential momentum accommodation(TMAC) is related to the energy of gas molecular,potential factor and temperature of the wall。...