NUMERICAL STUDY OF GAS EXPANSION IN A BOX USING THE GENERAL FOUR VELOCITY BROADWELL MODEL

In this paper we investigate the expansion of a gas in a box in the scope of discrete kinetic theory. The box is initially at rest and half-full filled of a gas. The general four velocity discrete model of Broadwell is retained for the modelling and the resulting mild problem is solved numerically using a fractional step method. The starting motion into the empty part of the box and the behaviour at large times of the gas is studied. An equilibrium state is attained after a transitional phase where the behaviour of the macroscopic variables of the flow depend on the set of the velocities of the model. The influence of the set of the velocities of the model vanishes in the steady state.