The state on each side described by 3 values.
Each wave family can cause a discontinuity:
- Sound waves can cause shocks or rarefaction waves.
- The material flow (entropy wave) can have a contact discontinuity.
The solution of Riemann problem (for convex - simple - EOS) can comprise:
- 0 or 1 contact discontinuity,
- 0, 1, or 2 shocks,
- 0, 1, or 2 rarefaction waves;
not more than 2 (shocks + rarefaction waves).