“…Resolving shock fronts is one of major difficulties in gas dynamics, which was handled through an approximate Riemann solver. The schemes in [20,25] are good only for hyperbolic systems of conservation laws, and only a single kind of material is considered in [20,25]. Since the Euler equations describe nonlinear wave interactions, a multicolor relaxation, instead of the multigrid method, has been used in [25] for the fast convergence of iterations.…”