An Eulerian algorithm for coupled simulations of elastoplastic-solids and condensed-phase explosives

In the presented algorithm, the ghost-fluid method is employed to represent the evolving material interfaces as discontinuities on discrete space. The coupling between the materials at these interfaces is achieved by means of a new approximate mixed Riemann solver, developed as part of this research. In addition we present a mixed Riemann solver for a simpler transport model, which ignores compaction effects at the interface. The robustness and accuracy of the developed solvers is demonstrated by comparisons against results from the original ghost-fluid method and exact solutions of model Riemann problems. To allow for more realistic material behaviour, the mixed Riemann solvers are subsequently extended to handle the shock Mie-Grüneisen equation of state, and an iterative procedure is suggested to increase accuracy as required. These mixed Riemann solvers demonstrate their suitability for explosive-solid interactions in two test cases of multi-phase detonations confined by an elastic-plastic solid.