A Riemann solver for a two-phase multicomponent process

A Riemann problem solver for an $(n + {\bf 1}) \times (n + 1)$ system of nonstrictly hyperbolic conservation laws is presented in an algorithmic form. The system models polymer flooding as an enhanced oil-recovery process. The Riemann problem solver is implemented and some examples of solutions are given. The exact solution of the Riemann problem is also used to study the behaviour of the classical Godunov method.