Strong shock waves in a dense gas: Burnett theory versus Monte Carlo simulation

plane shock waves in a hard-sphere fluid are analyzed within the framework of the Enskog theory. The results are obtained from two different approache s: (i) the approximate solutions of the Enskog equation at the levels of th e Navier-Stokes and the (linear) Burnett orders; and (ii) the exact solutio n of the Enskog equation obtained by means of a Monte Carlo simulation meth od. A comparison between the profiles of velocity, temperature, stress, and heat flux, as obtained from both approaches, is carried out. As expected, the shock becomes thinner (units of the mean free path) as the density decr eases and/or the Mach number increases. The approximate theoretical estimat es for the shock thickness are smaller than the simulation values, but this discrepancy becomes less important as the density increases. In general, t he linear Burnett theory is found to yield better results than the Navier-S tokes predictions, but both theories tend to overlap as the density increas es, and, surprisingly enough, the Navier-Stokes estimates are even slightly superior to those of the linear Burnett theory at high Mach numbers. [S106 3-651X(98)03012-8].