The Confined Lennard-Jones Two Piston System simulates a constant-energy two-dimensional system of particles confined by two frictionless pistons of equal mass M.   This computer model complements theoretical work describing the adiabatic expansion of an ideal gas using the quasi-static approximation.  Users can set the initial particle kinetic energy, Lennard Jones parameters, and the initial particle separation.  Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow.  The time evolution of temperature, pressure, and piston speed are shown in a second window.

Particles in this model have unit mass and interact through pairwise Lennard-Jones forces and hard-wall contact forces.  The instantaneous temperature is computed using the average particle kinetic energy and the pressure is computed using the virial expansion.

The Confined Lennard-Jones Two Piston System is a supplemental simulation for the article "Evolution of ideal gas mixtures confined in an insulated container by two identical pistons" by Joaquim Anacleto, Joaquim Alberto C. Anacleto, and J. M. Ferreira in the American Journal of Physics 79(10), 1009-1014 (2011) and has been approved by the authors and the American Journal of Physics (AJP) editor.  The Confined Lennard-Jones Two Piston System was created using the Easy Java Simulations (Ejs) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_stp_md_ConfinedLennardJonesTwoPistonSystem.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java.