Session S5 - Atoms and Ions.
ORAL session, Saturday morning, October 25
LaPaz, Memorial Union
A computer simulation has been written that simulates the evolution of a perturbed dilute gas using the Direct-Simulation Monte Carlo method, with the ultimate goal of adding collisions to a simulation of ultra-cold plasmas. As a test, it has been used to study fluid dynamic affects in one dimension using a small velocity perturbation so that comparison with standard gas-dynamic theory is possible. This comparison has been used to investigate the limitations on certain simulation parameters such as cell size, size of each time step, number of simulation particles, and mean-free-path. The simulation and the theory agree well when the mean-free path is a small fraction of the sound wavelength, but for long mean free paths the simulation and the theory diverge. As an illustration, the famous ``bell in a bell jar'' demonstration will be examined to see if wave damping might play a role.