The Riemann problem for scalar CJ-combustion model without convexity

The Riemann problem for scalar Chapman-Jouguet combustion modelis considered. The entropy conditions are extended from convex case tononconvex one. The existence and uniqueness of the corresponding entropysolutions are obtained constructively.The solutions consist of thegeneralized Chapman-Jouguet detonation and deflagration waves and strongdetonation waves as well as noncombustion waves.