WAVE STRUCTURE INDUCED BY FLUID-DYNAMIC LIMITS IN THE BROADWELL MODEL

Consider the fluid-dynamic limit problem for the Broadwell system of t he kinetic theory of gases, for Maxwellian Riemann initial data. The f ormal limit is the Riemann problem for a pair of conservation laws and is invariant under dilations of coordinates. The approach of self-sim ilar fluid-dynamic limits consists in replacing the mean free path in the Broadwell model so that the resulting problem preserves the invari ance under dilations. The limiting procedure was justified in [ST]. He re, we study the structure of the emerging solutions. We show that the y consist of two wave fans separated by a constant state. Each wave fa n is associated with one of the characteristic fields and is either a rarefaction wave or a shock wave. The shocks satisfy the Lax shock con ditions and have the internal structure of a Broadwell shock profile.