One-dimensional Brownian motion in hard rods: The adiabatic piston problem

We have investigated the motion characteristics of a movable piston immersed in a one-dimensional gas of hard rods by event-oriented molecular dynamics in the absence of thermal noise. Periodic and reflecting boundary conditions are explored. It is shown that the piston undergoes systematic oscillations with decaying amplitudes in short times before it comes to global thermodynamic equilibrium. Moreover, the diffusion of the piston is explored and analytical expressions for its equilibrium mean-squared displacement (MSD) are obtained. It is shown that the MSD of the piston does not differ much from the normal rods despite its mass and length are significantly larger. Copyright (C) EPLA, 2013