Calculating the effects of variations in composition on wave propagation in gases (Q1261943)

The equations of gas dynamics in one space dimension are solved whilst considering variations in gas composition and properties. A species continuity equation is derived and coupled in a single vector equation with the three usual conservation equations; the resulting system is solved directly in conservation law form using the two-step Lax-Wendroff technique. The effects of variable gas properties and composition on wave propagation are illustrated via the shock-tube, or Riemann, problem. Significant errors are introduced, in the cases investigated, by assuming that the fluid is a perfect gas of constant composition.